Author Topic: DIY Roof Replacement -- Metal over Ashphalt  (Read 2176 times)

JenniferW

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DIY Roof Replacement -- Metal over Ashphalt
« on: March 23, 2022, 04:31:21 AM »
This is an interesting video.  This guy is replacing his asphalt shingle roof with metal, by simply overlaying the metal over the shingles.  This allow one to do the roof in small sections over time.

I know metal roofs cost a lot more to install compared to asphalt but they also last for a very long time. 

But the ease of installation, by overlaying over the shingles, makes it looks approachable as a 1 or 2 man DIY job -- to be worked on over time.

https://www.youtube.com/watch?v=8cVDUV_z4TA

What do you think?   I know a metal roof might cost $10k to install instead of $5k for an asphalt roof.. but I know if you install yourself it might only be 1/4rd the cost.  So like $2.5k for metal roof if we DIY?

Sibley

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #1 on: March 23, 2022, 06:23:24 AM »
I'm no expert on roofs, but it seems to me that we as a species have been building and replacing roofs for a very long time, and we probably have the process fairly well figured out. Deviating significantly from that process may result in problems, and given that the intent of a roof is to keep the weather out of the house, those problems could cause much bigger problems. I'm not going to risk interior water damage.

You can DIY a metal roof and still do it right. My neighbor did it a few years ago.

Fishindude

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #2 on: March 23, 2022, 06:25:35 AM »
A lot get done that way, but it's not exactly the best way to install a metal roof.   Far better to strip off the old shingle roof so you can see what kind of shape your deck is in, know what you are screwing into, and have a nice flat surface to work off of.   It's not uncommon to see the entire metal roof (done like this) peel off in one big sheet including roof panels, furring and trims in severe wind conditions.

That is also the absolute cheapest roof panel you can use, basically just pole building siding.   A standing seam metal roof is a much better product.
Might do a shed or barn that way, but not my house.

BudgetSlasher

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #3 on: March 23, 2022, 06:57:08 AM »
DIY is doable and a lot gets done the way the video suggests. It is not best practice, but it is done.

I presume the 5 and 10k number are specific to your house and/location. I'd love to get a decent roof done for either price. I suspect a 75% reduction in cost by eliminating paying for labor is optimistic; 50-60 percent may be more realistic.

I do not know if it would be an issue, but I would be worried about how insurance might treat a DIY roofing job if there were ever an issue and they discovered it was DIY'ed.

Askel

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #4 on: March 23, 2022, 07:11:04 AM »
That is literally my exact roof setup. (except mine is white)

Would not recommend doing this unless financial needs dictate. Always better to do a full roof tear off and if you go metal, use a better product than just the ribbed steel panels. 

As others have noted, it won't let you inspect the decking during the replacement. It also makes it really hard to diagnose any leaks that might appear in the future as it's likely leaking in two different spots on the two different roofs. 

Also be prepared for the yearly ritual that is going up and tightening down all the screws that have backed themselves out. 

lthenderson

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #5 on: March 23, 2022, 07:38:36 AM »
I grew up on a large farm with maybe a dozen buildings with ribbed metal panels screwed to the wooden substructure below. After 20 years, there wasn't a single one that hadn't leaked somewhere and require trips up to the roof to silicone every fastener in the area of the leak, multiple times. The gaskets on the screws degrade with time and need replaced or silicone to prevent leaks. The guy in that video will have it even worse because with shingles underneath, he won't have any idea where the leak is coming from on his house as it will take some time to migrate to a point where it can get inside. As mentioned above, standing seam roofs would be a whole lot better option though with a caveat I will mention next.

As temperatures warm up and cool down, asphalt shingles expand and contract. As a result, the fasteners used to nail the wood furring strips to the roof will loosen over time. I once owned a house with metal roofing screwed directly down through shingles into the decking structure. Every single year I would have to get up on the roof and retighten down every single screw after the heat of summer was over as they would be sticking up off the surface a fraction of an inch. Screwing metal to wood furring helps to prevent this but doesn't prevent the degradation of the sealing washers mentioned above.

uniwelder

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #6 on: March 23, 2022, 08:20:58 AM »
Interesting to hear all the negative comments.  I never thought there was a serious issue installing a metal roof this way.  You don't want to put the metal directly on the shingles, but with purlins/strapping, ok.  Certainly its not 'the best', but for a diy job to save thousands of dollars, I would do it on my own house.  If you're sloppy/drunk/don't care, certainly the whole roof can tear off, but the point is that this is your own house and want to do it well--- make sure the screws are screwing into something.

I put on my own metal roofs (screwed down ag panel type) on a new construction garage, as well as replacing a 65 year old 5V metal roof on my previous house.  The old 5V panels were put on with lead capped nails, which about 1/4 were missing or uncapped by the time it was replaced, and the roof didn't leak by any amount that was noticeable.  The nails went through the ridges.

Ag panels aren't standing seam, but the absolute best isn't always necessary.  I've been told to ensure it stays leak free, screw through the ribs, rather than the flat section.  Goes against manufacturer instructions, but you're not relying on the rubber washer to seal.  Drawback is that it causes the screw to flex with expansion/contraction, so they'lll need to be replaced at some point before fatigue breaks them, perhaps 10 years is reasonable as preventative maintenance.  My garage went 15 before I sold the house, and I only retightened the screws once in that period and none had snapped.

As for the purlins/strapping, make sure it goes into the rafters/trusses.  Just have somebody stand in the attic while the top and near bottom rows are screwed in, make adjustments as needed, then mark for the remainder with a chalk line. 

As to cost, 75% off for DIY sounds realistic to me.  Hearing about quotes others received for their metal roofs shocked me.  Material pricing (not including the wood) is probably about $2-2.50 per sq ft of building footprint, based on panel cost of $1.10 per sq ft right now.  Panels were about half the total cost, and the remainder was screws/trim/etc.  Current price is about 2x what I paid-- material costs are very high right now.  The panel fabrication shop was just down the street from me, so I was able to buy from them directly. 

sonofsven

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #7 on: March 23, 2022, 08:52:14 AM »
For a really low budget diy roof look into the "tarp and tire" method, popular wherever blue tarps are sold, seems to work best with random junk littering the yard.
I wouldn't do the metal roof over asphalt on a house, for the same reasons Fishindude stated.
Why spend good money on a metal roof only to scrimp on the install?
Penny wise, pound foolish.

AccidentialMustache

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #8 on: March 23, 2022, 06:05:25 PM »
Those are gaps between the wooden rails seem like prime dent spots. Tree branch in a storm? Working up there and lose your balance and fall there? No support for an inch underneath? Yeah.

The air gap doesn't seem to have a real exit. Penned in by shingles below, wood around, and steel above. It'll condense water sooner or later (humid day and the sun goes down, roof temp drops and there ya go!) and then you can grow some nice mold in that protected cavity.

I don't know the size of house you're talking but we just did tearoff+standing seam (eg, no exposed fasteners, so no leaking through them after a few years) and it was "well above" 10k installed.

uniwelder

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #9 on: March 24, 2022, 07:43:33 AM »
Those are gaps between the wooden rails seem like prime dent spots. Tree branch in a storm? Working up there and lose your balance and fall there? No support for an inch underneath? Yeah.

The air gap doesn't seem to have a real exit. Penned in by shingles below, wood around, and steel above. It'll condense water sooner or later (humid day and the sun goes down, roof temp drops and there ya go!) and then you can grow some nice mold in that protected cavity.

I don't know the size of house you're talking but we just did tearoff+standing seam (eg, no exposed fasteners, so no leaking through them after a few years) and it was "well above" 10k installed.

For purlins, 24" OC is pretty common.  I put mine at 18" and couldn't tell the difference when I walked on it whether I was over solid wood or in the center of the span.  Ag panels are ribbed every 9", so there's lots of support and they don't dent as easily as you might think.

The air gap is something concerning and I'd be curious to ask around about.  Since mine was over fulled exposed purlins, there is a huge amount of airflow and condensation wasn't an issue.  In the youtube video from the OP, it looks like he completely seals the upper and lower ends, so there might be minimal humidity to condense.  I guess that depends on what evaporates through the attic and is trapped in that space.

As I mentioned in an above post, current pricing should end up around $2-2.50 per sq ft of building footprint, plus cost of lumber.  For a 1,500 sq ft house, that might end up around $4-5,000 total for materials in today's inflated prices vs 2 years ago.

Fishindude

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #10 on: March 24, 2022, 09:41:33 AM »
Another comment regarding the ribbed metal roofs like this.   Things get considerably more difficult and harder to keep leak free if you have hips, valleys or large penetrations to deal with.

YttriumNitrate

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #11 on: March 24, 2022, 10:09:25 AM »
About 10 years ago, at my old house I installed a metal roof over top of the existing asphalt root (not DIY). So far, it has worked wonderfully and still looks great. Unlike the house in the video, an underlayment layer was put between the asphalt and metal.

The one thing I noticed about the video is that he installed exposed fastener panels. In my opinion, that's about the most penny-wise pound foolish thing you can do with a metal roof. Hidden fastener panels are more expensive, and probably more difficult to install, but they don't start leaking when the rubber washers eventually break down.
« Last Edit: March 24, 2022, 10:26:22 AM by YttriumNitrate »

NaN

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #12 on: March 25, 2022, 07:12:28 PM »
When I bought my house it had a standing seam roof. Are they really not worth the costs? It seems the hassle with screws and fastener seals would be obnoxious (granted I have seals around the penetrations).

sonofsven

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #13 on: March 25, 2022, 08:47:47 PM »
When I bought my house it had a standing seam roof. Are they really not worth the costs? It seems the hassle with screws and fastener seals would be obnoxious (granted I have seals around the penetrations).

No, they're excellent roofs, it's what I have on my house as well.

JenniferW

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #14 on: March 25, 2022, 08:48:44 PM »
About 10 years ago, at my old house I installed a metal roof over top of the existing asphalt root (not DIY). So far, it has worked wonderfully and still looks great. Unlike the house in the video, an underlayment layer was put between the asphalt and metal.

The one thing I noticed about the video is that he installed exposed fastener panels. In my opinion, that's about the most penny-wise pound foolish thing you can do with a metal roof. Hidden fastener panels are more expensive, and probably more difficult to install, but they don't start leaking when the rubber washers eventually break down.

Thanks for pointing this out. I just watched the following video, and I'd definitely go with Standing Seam panels (hidden fasteners).  Look both aesthetically better and will prevent leaks like you say.

https://www.youtube.com/watch?v=fdn6tAjemYg

When installing these panels is it possible to partially strip asphalt shingles/paper off the roof, lay the felt and panels, all in sections?    That way it can become a DIY project instead of expensive labor.
« Last Edit: March 25, 2022, 08:50:32 PM by JenniferW »

uniwelder

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #15 on: March 26, 2022, 07:34:59 AM »
About 10 years ago, at my old house I installed a metal roof over top of the existing asphalt root (not DIY). So far, it has worked wonderfully and still looks great. Unlike the house in the video, an underlayment layer was put between the asphalt and metal.

The one thing I noticed about the video is that he installed exposed fastener panels. In my opinion, that's about the most penny-wise pound foolish thing you can do with a metal roof. Hidden fastener panels are more expensive, and probably more difficult to install, but they don't start leaking when the rubber washers eventually break down.
Thanks for pointing this out. I just watched the following video, and I'd definitely go with Standing Seam panels (hidden fasteners).  Look both aesthetically better and will prevent leaks like you say.

https://www.youtube.com/watch?v=fdn6tAjemYg

When installing these panels is it possible to partially strip asphalt shingles/paper off the roof, lay the felt and panels, all in sections?    That way it can become a DIY project instead of expensive labor.

I have a diy friend who is going to put standing seam on his house soon, and I asked to help him out a little to learn the process.  Its not true standing seam, but rather 'snap and lock' which serves the same purpose but is supposed to be easier to install.  Its from the same local roofing manufacturer, but costs about 3x more than the ag panels--- $3.05 vs $1.10 per sq ft for the panels themselves.  He says total cost for all materials is going to run him about 14k to cover his 2,000 sq ft house, so $7/sq ft total.

One of the reasons the cost is so much higher for standing seam is because the panels aren't stackable like ag panels.  To get around the shipping problems, the company has the forming equipment on a trailer, so they drive to your job site, and then roll out the panels there and cut to length.  Otherwise, the panels are a heavier gauge metal, so more expensive there as well.

He is also planning to lay purlins across the existing asphalt shingles and attach the new roof to those.  I'm going to pass along this discussion to him and see what he thinks.  I think the work is happening in the next month.

NaN

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #16 on: March 26, 2022, 09:07:52 PM »


About 10 years ago, at my old house I installed a metal roof over top of the existing asphalt root (not DIY). So far, it has worked wonderfully and still looks great. Unlike the house in the video, an underlayment layer was put between the asphalt and metal.

The one thing I noticed about the video is that he installed exposed fastener panels. In my opinion, that's about the most penny-wise pound foolish thing you can do with a metal roof. Hidden fastener panels are more expensive, and probably more difficult to install, but they don't start leaking when the rubber washers eventually break down.
Thanks for pointing this out. I just watched the following video, and I'd definitely go with Standing Seam panels (hidden fasteners).  Look both aesthetically better and will prevent leaks like you say.

https://www.youtube.com/watch?v=fdn6tAjemYg

When installing these panels is it possible to partially strip asphalt shingles/paper off the roof, lay the felt and panels, all in sections?    That way it can become a DIY project instead of expensive labor.

I have a diy friend who is going to put standing seam on his house soon, and I asked to help him out a little to learn the process.  Its not true standing seam, but rather 'snap and lock' which serves the same purpose but is supposed to be easier to install.  Its from the same local roofing manufacturer, but costs about 3x more than the ag panels--- $3.05 vs $1.10 per sq ft for the panels themselves.  He says total cost for all materials is going to run him about 14k to cover his 2,000 sq ft house, so $7/sq ft total.

One of the reasons the cost is so much higher for standing seam is because the panels aren't stackable like ag panels.  To get around the shipping problems, the company has the forming equipment on a trailer, so they drive to your job site, and then roll out the panels there and cut to length.  Otherwise, the panels are a heavier gauge metal, so more expensive there as well.

He is also planning to lay purlins across the existing asphalt shingles and attach the new roof to those.  I'm going to pass along this discussion to him and see what he thinks.  I think the work is happening in the next month.

That is interesting the sheet metal work happens on site. Seems like a big box store could sell the same strips and form them to customer request lengths and be much cheaper, and even deliver on a long trailer.

Fishindude

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #17 on: March 27, 2022, 08:06:22 AM »
That is interesting the sheet metal work happens on site. Seems like a big box store could sell the same strips and form them to customer request lengths and be much cheaper, and even deliver on a long trailer.

Sounds like somebody in the area just happens to have a roof roll forming machine.
Getting long sheets delivered is not a huge issue as long as you have the ability to unload them.   40' & 50' Roof sheets are hauled by truck every day.

YttriumNitrate

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #18 on: March 27, 2022, 08:51:17 AM »
Here are the exact snap together panels that I used on my house. They were delivered by a truck with a neat little forklift on the back.

https://www.menards.com/main/building-materials/roofing/metal-roofing/cut-to-length-premium-pro-snap-reg-steel-panel/bronze1559814-32/p-1444448555354.htm

uniwelder

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #19 on: March 27, 2022, 04:47:07 PM »
That is interesting the sheet metal work happens on site. Seems like a big box store could sell the same strips and form them to customer request lengths and be much cheaper, and even deliver on a long trailer.

Sounds like somebody in the area just happens to have a roof roll forming machine.
Getting long sheets delivered is not a huge issue as long as you have the ability to unload them.   40' & 50' Roof sheets are hauled by truck every day.

I used to live 10 minutes from the roof panel shop.  They roll everything from 10,000 lb coils and bend all the trim there.  They also have another rig for forming the standing seam panels onsite.  It was very convenient because I could order and in three days they'd have it all ready and plop it on top of my truck rack.  They also keep a few trailers around to rent, so people can haul their own panels.  My friend that is doing his roof soon lives about 20 minutes away.

The standing seam panels I'm familiar with can't be stacked without a lot of hassle creating wooden racks to separate each panel.  Its labor intensive and wastes a lot of lumber.  The edges rise up 90 degrees and flare out, so they don't nest.  Stacking would result in scratches or other bending.  Therefore, the truck just comes out to the site, assuming you're close enough.  The ag panels are completely different, and 30 panels, 20 feet long, enough to cover my 1,500 sq ft garage, was maybe an inch thick.

uniwelder

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #20 on: March 27, 2022, 04:51:05 PM »
Here are the exact snap together panels that I used on my house. They were delivered by a truck with a neat little forklift on the back.

https://www.menards.com/main/building-materials/roofing/metal-roofing/cut-to-length-premium-pro-snap-reg-steel-panel/bronze1559814-32/p-1444448555354.htm

Interesting!  That looks very DIY friendly.  Not at all what I think of regarding panel style.  I wish Menards existed around me.  They seem to carry a lot of products that I can't get.

NorCal

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #21 on: March 27, 2022, 06:24:50 PM »
My dad did a DIY barn roof with metal a few years back.

His feedback is that the vast majority of the work is in the prep of making sure everything is aligned perfectly straight. Even a minor partial-degree misalignment will add up over the span of a roofline.

Based on this, Id say a big consideration is how complex your roof shape is. 

lthenderson

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #22 on: March 28, 2022, 12:34:57 PM »
An easy way to see a novice DIY job is to just sight along the end of the roof above the gutter. If it looks like a bunch of stair steps, they didn't do a very good job starting that initial sheet.

ChpBstrd

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #23 on: March 28, 2022, 01:11:51 PM »
I installed exposed-fastener metal roof on my 700sf shop about 3 years ago at a cost of $2500 in materials. Removal of the old roofing was not easy, but it wasn't hard either. I generally used a flat shovel and a roofing shovel, and sometimes a hammer and flatbar. Together, those tools took me down to the bare wood in a few evenings of work. This revealed I had several areas where repairs were needed. In some spots I left the old tar paper in place because laziness. The old roofing went into cardboard boxes, out to the curb, and off to the dump.

I cut out about 6" of the sheathing at the peaks for a ridge vent. This allowed me to see the rafters, which came in handy as I tried to generally hit them instead of screwing only through plywood.

I installed the drip edge trim at the bottom of the roof.

Then I rolled out the manufacturer's recommended vapor barrier. This is necessary because condensation can form on the bottom side of metal roofing, and you want to keep that water off the wood. The vapor barrier was attached with button cap nails.

Then I screwed down the panels, which had been factory-cut to my required length. Despite my best efforts, they went in with about 1/2" deflection, but oh well. You'd have to be looking for the misalignment to notice it.

Edge trim and the ridge cap finished off the job.

WRT the concerns about screws backing out and rubber washers deteriorating, I'll probably climb up there to do an inspection soon. I might also put a little dab of aluminum reinforced tar on each screw to encase the rubber seal for a few years. Someday when the finish is worn off and rust is starting to show, I'll mop aluminum reinforced tar across the whole roof and give it another decade.

Bottom line, removing the old shingles isn't such a hard job that it's worth skipping. I'm confident my roof job will last 25+ years, but I'm not sure how I'd feel if I had to think about old nails or asphalt rocks rubbing through the finish on the bottom of my metal panels.

The hard part of such an install is not slipping off the steep sections of roof. Metal roofing is SLICK. I couldn't even set my tools down or they'd go off the edge. The good news is that your exposed rafters near the ridge serve as great places to tie a rope.

Fishindude

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #24 on: March 28, 2022, 01:22:07 PM »
WRT the concerns about screws backing out and rubber washers deteriorating, I'll probably climb up there to do an inspection soon. I might also put a little dab of aluminum reinforced tar on each screw to encase the rubber seal for a few years. Someday when the finish is worn off and rust is starting to show, I'll mop aluminum reinforced tar across the whole roof and give it another decade.

If they are screwed into a good substrate, your screws will not loosen or back out.  The rubber washers on modern roof screws will not deteriorate anytime soon either.  If you're not having problems, stay off the roof, and no need to dab tar on the screws.   If your panels are alumanized (bare silver) or one of the high quality painted panels, your finish is not going to wear off anytime soon either.

Most of the worries like mentioned were common issues with old metal roof materials and pole buildings.  Todays products are much better.

ChpBstrd

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #25 on: March 28, 2022, 03:36:23 PM »
WRT the concerns about screws backing out and rubber washers deteriorating, I'll probably climb up there to do an inspection soon. I might also put a little dab of aluminum reinforced tar on each screw to encase the rubber seal for a few years. Someday when the finish is worn off and rust is starting to show, I'll mop aluminum reinforced tar across the whole roof and give it another decade.

If they are screwed into a good substrate, your screws will not loosen or back out.  The rubber washers on modern roof screws will not deteriorate anytime soon either.  If you're not having problems, stay off the roof, and no need to dab tar on the screws.   If your panels are alumanized (bare silver) or one of the high quality painted panels, your finish is not going to wear off anytime soon either.

Most of the worries like mentioned were common issues with old metal roof materials and pole buildings.  Todays products are much better.

I think the worries are also about some of the lower-quality products sold at discount warehouses and hardware stores with thin layers of galvanization, installed with rubber-washered roofing nails over flexing roof decks. These were the materials used in those 70-year-old rusty-roofed barns you see while driving rural highways. 

YttriumNitrate

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #26 on: March 28, 2022, 03:49:00 PM »
I think the worries are also about some of the lower-quality products sold at discount warehouses and hardware stores with thin layers of galvanization, installed with rubber-washered roofing nails over flexing roof decks. These were the materials used in those 70-year-old rusty-roofed barns you see while driving rural highways.
While materials have definitely been improving, even somewhat modern metal roofs have also had issues. My friends' parents had a house built in the late 90s with an exposed fastener metal roof and had issues with the washers leaking.

uniwelder

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #27 on: May 12, 2022, 01:19:49 PM »
I have a diy friend who is going to put standing seam on his house soon, and I asked to help him out a little to learn the process.  Its not true standing seam, but rather 'snap and lock' which serves the same purpose but is supposed to be easier to install.  Its from the same local roofing manufacturer, but costs about 3x more than the ag panels--- $3.05 vs $1.10 per sq ft for the panels themselves.  He says total cost for all materials is going to run him about 14k to cover his 2,000 sq ft house, so $7/sq ft total.

One of the reasons the cost is so much higher for standing seam is because the panels aren't stackable like ag panels.  To get around the shipping problems, the company has the forming equipment on a trailer, so they drive to your job site, and then roll out the panels there and cut to length.  Otherwise, the panels are a heavier gauge metal, so more expensive there as well.

He is also planning to lay purlins across the existing asphalt shingles and attach the new roof to those.  I'm going to pass along this discussion to him and see what he thinks.  I think the work is happening in the next month.

Update-- The truck/trailer came to my friend's house today.  I got to watch the setup and help stack panels as they rolled out from the machine.  It took the guy about 30 minutes to get everything running, and then another 1 1/2 hours to get all the roofing formed.  He drove a couple hours from Tennessee and scheduled this job with another one nearby. 

The panel shape was not what I was expecting.  It was exactly the same type described here---
Here are the exact snap together panels that I used on my house. They were delivered by a truck with a neat little forklift on the back.

https://www.menards.com/main/building-materials/roofing/metal-roofing/cut-to-length-premium-pro-snap-reg-steel-panel/bronze1559814-32/p-1444448555354.htm
The guy operating the equipment said they generally won't deliver the product already formed because of scratching during the haul and the hassle of stacking.  YttriumNitrate--- did you have any scratching issues?  Was there anything between panels to protect them?  The same machine will also create another style of snap lock type panel by swapping out some rollers that the operator said is used for longer sections and allows for more expansion/contraction with a different fastening system.  I didn't get to ask more about it, however.

As for opinions on how to do the roofing, he recommended no purlins over the asphalt shingles, but instead to put a particular membrane material on the shingles, then fasten directly through.  It wasn't even a cost cutting measure, as my friend already had the stack of 1x4's laying on the ground.  He said the extra air gap will cause condensation to collect at the horizontal purlins and rot them out.  As for exposed fastener ag panels, he says the manufacturer directs their customers to put the screws through the ridges, not the flats.  I asked why every other manufacturer tells people to put it through the flats, and he said he couldn't make sense of it either.  He seems to have been installing metal roofing a long time (looked to be about 60 years old) and been running this particular rig for the past 16 years, so I find it quite interesting that everyone has a different opinion on the best way to install the same product.
« Last Edit: May 12, 2022, 01:23:45 PM by uniwelder »

lthenderson

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #28 on: May 13, 2022, 10:17:40 AM »
As for exposed fastener ag panels, he says the manufacturer directs their customers to put the screws through the ridges, not the flats.  I asked why every other manufacturer tells people to put it through the flats, and he said he couldn't make sense of it either. 

The reason they tell you that is for when the washer degrades into dust years from now, it will reduce the amount of moisture that can get into the now exposed hole by being on the ridge versus the flat.

YttriumNitrate

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #29 on: May 13, 2022, 11:08:40 AM »
The guy operating the equipment said they generally won't deliver the product already formed because of scratching during the haul and the hassle of stacking.  YttriumNitrate--- did you have any scratching issues?  Was there anything between panels to protect them?  The same machine will also create another style of snap lock type panel by swapping out some rollers that the operator said is used for longer sections and allows for more expansion/contraction with a different fastening system.  I didn't get to ask more about it, however.
It's been a while, but I remember that the panels came in two or three wooden boxes that had the height and width of a coffin and were 20+ feet long. There might been cardboard or heavy between each of the panels, but I don't remember. I assume they were packed at the Midwest Manufacturing factory and then shipped. However they packed them, they must have done a good job as there were no issues with scratching.

zolotiyeruki

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #30 on: May 13, 2022, 12:06:07 PM »
As for opinions on how to do the roofing, he recommended no purlins over the asphalt shingles, but instead to put a particular membrane material on the shingles, then fasten directly through.  It wasn't even a cost cutting measure, as my friend already had the stack of 1x4's laying on the ground.  He said the extra air gap will cause condensation to collect at the horizontal purlins and rot them out. 
I don't think I've ever heard of someone installing purlins horizontally.  I mean, the whole point of the purlins is to allow any water that gets past the panels to drip down, and to airflow up to dry anything that's left.

uniwelder

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #31 on: May 13, 2022, 05:35:30 PM »
As for exposed fastener ag panels, he says the manufacturer directs their customers to put the screws through the ridges, not the flats.  I asked why every other manufacturer tells people to put it through the flats, and he said he couldn't make sense of it either. 

The reason they tell you that is for when the washer degrades into dust years from now, it will reduce the amount of moisture that can get into the now exposed hole by being on the ridge versus the flat.

I totally understand and agree with you (though I think you misunderstood what I was saying), however, nearly every manufacturer tells you to do the opposite.  Proper installation from most is that the screws should be through the flat.  The logic is that the screw is in shear, rather than bending and eventually fatiguing the screw if its in the ridge.

uniwelder

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #32 on: May 13, 2022, 05:41:26 PM »
As for opinions on how to do the roofing, he recommended no purlins over the asphalt shingles, but instead to put a particular membrane material on the shingles, then fasten directly through.  It wasn't even a cost cutting measure, as my friend already had the stack of 1x4's laying on the ground.  He said the extra air gap will cause condensation to collect at the horizontal purlins and rot them out. 
I don't think I've ever heard of someone installing purlins horizontally.  I mean, the whole point of the purlins is to allow any water that gets past the panels to drip down, and to airflow up to dry anything that's left.

You mean installing purlins horizontally over an existing roof?  Whether or not thats advisable has been discussed a little bit on this thread already.  I mentioned it because its another data point from someone in the metal roofing business, which it seems even the experts don't have consistent advice about what is ok or not.

ChpBstrd

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #33 on: May 13, 2022, 08:04:54 PM »
As for opinions on how to do the roofing, he recommended no purlins over the asphalt shingles, but instead to put a particular membrane material on the shingles, then fasten directly through.  It wasn't even a cost cutting measure, as my friend already had the stack of 1x4's laying on the ground.  He said the extra air gap will cause condensation to collect at the horizontal purlins and rot them out. 
I don't think I've ever heard of someone installing purlins horizontally.  I mean, the whole point of the purlins is to allow any water that gets past the panels to drip down, and to airflow up to dry anything that's left.
That would be ideal, but because of the direction of the corrugation, the panels would sag along the long axis if the purlins were vertical. My metal roof went right on top of the decking, with a vapor barrier between the metal and the wood to address the condensation issue.

zolotiyeruki

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #34 on: May 13, 2022, 11:24:12 PM »
As for opinions on how to do the roofing, he recommended no purlins over the asphalt shingles, but instead to put a particular membrane material on the shingles, then fasten directly through.  It wasn't even a cost cutting measure, as my friend already had the stack of 1x4's laying on the ground.  He said the extra air gap will cause condensation to collect at the horizontal purlins and rot them out. 
I don't think I've ever heard of someone installing purlins horizontally.  I mean, the whole point of the purlins is to allow any water that gets past the panels to drip down, and to airflow up to dry anything that's left.
That would be ideal, but because of the direction of the corrugation, the panels would sag along the long axis if the purlins were vertical. My metal roof went right on top of the decking, with a vapor barrier between the metal and the wood to address the condensation issue.
What I've seen most often is purlins installed diagonally--that way, you get both venting and support across each panel.

lthenderson

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #35 on: May 14, 2022, 06:03:54 AM »
As for exposed fastener ag panels, he says the manufacturer directs their customers to put the screws through the ridges, not the flats.  I asked why every other manufacturer tells people to put it through the flats, and he said he couldn't make sense of it either. 

The reason they tell you that is for when the washer degrades into dust years from now, it will reduce the amount of moisture that can get into the now exposed hole by being on the ridge versus the flat.

I totally understand and agree with you (though I think you misunderstood what I was saying), however, nearly every manufacturer tells you to do the opposite.  Proper installation from most is that the screws should be through the flat.  The logic is that the screw is in shear, rather than bending and eventually fatiguing the screw if its in the ridge.

I have installed dozens of metal roofs over the years. Back when we didn't know any better, we installed the screws in the ridges and invariably got leaks. We quickly realized that and switched to the recommended flat part of the panels but still got leaks. Those installed over shingles, leaked much worse and sooner as the shingle expansion and all the air gaps between layers made it nearly impossible to get the fastener tight enough in the beginning and then not loosen with time. As a result, I will never put another metal roof with exposed fasteners on a roof with shingles. It is much much much better to install directly onto solid wood using fasteners on the flat part of the metal. However, that too isn't totally leak proof. You are sandwiching between the fastener head and the metal surface a material that with exposure to sun, temperature and hydration changes becomes brittle and disintegrates with time. The washer materials have gotten a lot better with time but from what I have seen, it only extends the life and doesn't prevent the inevitable, leaking. Of all those dozens of roofs installed from the early 80's on, they all have one things in common. No matter how we screwed them on, they have leaked. While for our purposes of storing farm machinery, livestock and other things, leaking isn't much more than nuisance. The one house I owned with metal roofing screwed in the flat parts of the steel directly over shingles (no purlins) that the previous owner had installed, also shared a trait with all those farm building roofs I installed in my early years, it too leaked in several places. I was out there annually tightening screws, replacing washers and dabbing on copious amounts of silicone to protect my investment. I swore the day I sold that place I would never make the mistake of buying a house with exposed fastener metal roof on it ever again.

ChpBstrd

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #36 on: May 14, 2022, 10:38:40 AM »
As for exposed fastener ag panels, he says the manufacturer directs their customers to put the screws through the ridges, not the flats.  I asked why every other manufacturer tells people to put it through the flats, and he said he couldn't make sense of it either. 

The reason they tell you that is for when the washer degrades into dust years from now, it will reduce the amount of moisture that can get into the now exposed hole by being on the ridge versus the flat.

I totally understand and agree with you (though I think you misunderstood what I was saying), however, nearly every manufacturer tells you to do the opposite.  Proper installation from most is that the screws should be through the flat.  The logic is that the screw is in shear, rather than bending and eventually fatiguing the screw if its in the ridge.

I have installed dozens of metal roofs over the years. Back when we didn't know any better, we installed the screws in the ridges and invariably got leaks. We quickly realized that and switched to the recommended flat part of the panels but still got leaks. Those installed over shingles, leaked much worse and sooner as the shingle expansion and all the air gaps between layers made it nearly impossible to get the fastener tight enough in the beginning and then not loosen with time. As a result, I will never put another metal roof with exposed fasteners on a roof with shingles. It is much much much better to install directly onto solid wood using fasteners on the flat part of the metal. However, that too isn't totally leak proof. You are sandwiching between the fastener head and the metal surface a material that with exposure to sun, temperature and hydration changes becomes brittle and disintegrates with time. The washer materials have gotten a lot better with time but from what I have seen, it only extends the life and doesn't prevent the inevitable, leaking. Of all those dozens of roofs installed from the early 80's on, they all have one things in common. No matter how we screwed them on, they have leaked. While for our purposes of storing farm machinery, livestock and other things, leaking isn't much more than nuisance. The one house I owned with metal roofing screwed in the flat parts of the steel directly over shingles (no purlins) that the previous owner had installed, also shared a trait with all those farm building roofs I installed in my early years, it too leaked in several places. I was out there annually tightening screws, replacing washers and dabbing on copious amounts of silicone to protect my investment. I swore the day I sold that place I would never make the mistake of buying a house with exposed fastener metal roof on it ever again.
This is why Im strongly considering walking my 3 year old metal roof and putting a dab of aluminum reinforced roof sealant on top of each screw. The shelter might buy the rubber washers another 5-10 years.

Fishindude

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #37 on: May 14, 2022, 10:43:02 AM »
With exposed fastener metal roofs you have to have solid substructure to anchor down to.  You put the panels in the flats per the manufacturer so they suck down tight with no allowance for movement that could lead to leaks.   Going right over shingles is a bad idea, but I still see people doing it all the time.

Prior to retirement I was contractor and we built hundreds of building with metal roofs.   
Some good guidelines for exposed fastener metal roofs:
a. 2:12 or steeper slope is desirable.   
b. Single sheets, ridge to eave of about 40' is max you want to go.   End laps lead to leaks and runs much longer than 40' expand / contract too much with temp swings and will elongate the fastener holes.
c. Avoid using exposed fastener metal roofs if you have may hips, valleys or penetrations, they are much more difficult to flash weathertight at these items -vs- a standing seam roof.

Follow these guidelines and the manufacturers instructions and you won't have leak problems.

Fishindude

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #38 on: May 14, 2022, 10:48:25 AM »
This is why Im strongly considering walking my 3 year old metal roof and putting a dab of aluminum reinforced roof sealant on top of each screw. The shelter might buy the rubber washers another 5-10 years.

This myth about the rubber washers deteriorating is mostly nonsense.  Maybe the fasteners from the 1970's or 80's were bad, but todays fasteners will outlast you.
Rather than a dab of goop on the screws, you'd be better off to carefully walk the roof with a hand ratchet and long extension and simply snug up any loose fasteners, taking care not to strip them.  If you strip them, replace with the next diameter larger screw.  If it's not leaking, best thing you can do is stay off the roof, as your foot traffic can actually break the seals on fasteners and create leaks that weren't there previously.

As I'm typing this response, I'm sitting in a 27 year old building with a 2:12 slope screw down roof that has been leak free from day one.
« Last Edit: May 14, 2022, 10:50:37 AM by Fishindude »

middo

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #39 on: May 21, 2022, 11:32:10 PM »
Chiming in with an Australian perspective here.  A significant portion of all home rooves here are Colorbond, which is a trademark steel roofing product that comes in various colours, but is effectively a corrugated steel sheet roofing system.  They do not leak.  They only leak under certain circumstances:
  • The screws are fixed in the valleys rather than the top of the ridges
  • Weatherproofing (bending up the top end of the valleys) is not done
  • Hips and valleys in the roof line are not fitted with appropriate products

A video of the system being used is here:

https://www.youtube.com/watch?v=KMx5Nh8IVhY

The screws are visible, but once installed, it lasts for many years.  Screws do not need to be refastened, and the rooves do not peel off under strong winds.  They can be installed in cyclone areas with the addition of an extra washer and appropriate framing.  I have 3 houses with this type of roofing, and our unit in a complex is about to get this type of roofing fitted as well.  none leak.

NaN

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #40 on: May 22, 2022, 11:43:05 AM »
picture

That's awesome. The video posted by @JenniferW mentioned thermal expansion issues and gauge. The thermal expansion issue makes a lot of sense for fastener wear and is highly dependent on climate and if the roof is shaded. The gauge definitely explains the price difference. Plus the labor and maintenance of many of those forming machines. I guess there is some savings on transport of the metal.

we installed the screws in the ridges and invariably got leaks.

Chiming in with an Australian perspective here. 

[Video with screws on ridges]

There seems to be no consensus!

BudgetSlasher

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #41 on: May 22, 2022, 03:00:05 PM »
Looking at this from a different perspective, I probably would not do anything with my roof that was outside of what is locally accepted and avoid anything that has a bad reputation locally. There are plenty of products and methods that have vastly different reputation based on location, some are due to climate and some are due to prior poor installations.

If I ever went to sell I would not want a new-ish roof being a detractor.

ChpBstrd

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #42 on: May 23, 2022, 06:58:27 AM »
Chiming in with an Australian perspective here.  A significant portion of all home rooves here are Colorbond, which is a trademark steel roofing product that comes in various colours, but is effectively a corrugated steel sheet roofing system.  They do not leak.  They only leak under certain circumstances:
  • The screws are fixed in the valleys rather than the top of the ridges
  • Weatherproofing (bending up the top end of the valleys) is not done
  • Hips and valleys in the roof line are not fitted with appropriate products

A video of the system being used is here:

https://www.youtube.com/watch?v=KMx5Nh8IVhY

The screws are visible, but once installed, it lasts for many years.  Screws do not need to be refastened, and the rooves do not peel off under strong winds.  They can be installed in cyclone areas with the addition of an extra washer and appropriate framing.  I have 3 houses with this type of roofing, and our unit in a complex is about to get this type of roofing fitted as well.  none leak.

Thanks for a very interesting video. It's utterly alien from a US perspective in everything from the framing to the way insulation is done to the way the metal is measured. I'm very surprised that the screws hold well when run through soft insulation. I was also surprised to see relatively little deflection or kinking when the installer was walking across the material or when the screws went down snug. I did 15 seconds of googling to figure out the conversion from BMT (base metal thickness) to gauge (how things are measured in the US, because weirdness) and this metal would be equivalent to about 26 gauge. What kind of Aussie magic keeps it from bending?

In the US, the corrugated pattern is considered "rustic" or reminiscent of an old farm house or barn. It's thought that patterns with sharper bends look more modern and have more strength due to the flat part of the metal sitting flat against the boards. The idea is that you have to screw a flat piece of metal to a flat board to get it snug, and if you go through the peaks you'll just smash the peak down and create a leak. Either that or it'll bend the screw back and forth due to expansion and contraction due to it not being snug.

We have all sorts of reasons why the design in that video won't work, but as you say, it does work. It works across an entire continent. You say it lasts for "many years" but how long is that? 25 years?

lthenderson

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #43 on: May 23, 2022, 10:18:41 AM »
Thanks for a very interesting video. It's utterly alien from a US perspective in everything from the framing to the way insulation is done to the way the metal is measured. I'm very surprised that the screws hold well when run through soft insulation. I was also surprised to see relatively little deflection or kinking when the installer was walking across the material or when the screws went down snug. I did 15 seconds of googling to figure out the conversion from BMT (base metal thickness) to gauge (how things are measured in the US, because weirdness) and this metal would be equivalent to about 26 gauge. What kind of Aussie magic keeps it from bending?

In the US, the corrugated pattern is considered "rustic" or reminiscent of an old farm house or barn. It's thought that patterns with sharper bends look more modern and have more strength due to the flat part of the metal sitting flat against the boards. The idea is that you have to screw a flat piece of metal to a flat board to get it snug, and if you go through the peaks you'll just smash the peak down and create a leak. Either that or it'll bend the screw back and forth due to expansion and contraction due to it not being snug.

We have all sorts of reasons why the design in that video won't work, but as you say, it does work. It works across an entire continent. You say it lasts for "many years" but how long is that? 25 years?

For me, the big grain of salt is that the wettest state in Australia gets less rain than all but the 10 driest states in the U.S. on average.

There is no magic with corrugated metal like what was shown in the video. It is incredibly rigid and when supported every 18 inches or so as they did in the video, it can hold up a light man reasonably well. However, it did flex quite a bit when even he walked in-between the nailers.

Gronnie

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #44 on: May 23, 2022, 01:29:58 PM »
Grunch (didn't read responses yet):

It's not the asphalt or metal that's waterproof, it's the underlayment. If the roof has issues, putting another layer over the top won't do much long term to help. It's always better to tear down to the decking when replacing roofing.

middo

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #45 on: May 23, 2022, 05:58:50 PM »
Chiming in with an Australian perspective here.  A significant portion of all home rooves here are Colorbond, which is a trademark steel roofing product that comes in various colours, but is effectively a corrugated steel sheet roofing system.  They do not leak.  They only leak under certain circumstances:
  • The screws are fixed in the valleys rather than the top of the ridges
  • Weatherproofing (bending up the top end of the valleys) is not done
  • Hips and valleys in the roof line are not fitted with appropriate products

A video of the system being used is here:

https://www.youtube.com/watch?v=KMx5Nh8IVhY

The screws are visible, but once installed, it lasts for many years.  Screws do not need to be refastened, and the rooves do not peel off under strong winds.  They can be installed in cyclone areas with the addition of an extra washer and appropriate framing.  I have 3 houses with this type of roofing, and our unit in a complex is about to get this type of roofing fitted as well.  none leak.

Thanks for a very interesting video. It's utterly alien from a US perspective in everything from the framing to the way insulation is done to the way the metal is measured. I'm very surprised that the screws hold well when run through soft insulation. I was also surprised to see relatively little deflection or kinking when the installer was walking across the material or when the screws went down snug. I did 15 seconds of googling to figure out the conversion from BMT (base metal thickness) to gauge (how things are measured in the US, because weirdness) and this metal would be equivalent to about 26 gauge. What kind of Aussie magic keeps it from bending?

In the US, the corrugated pattern is considered "rustic" or reminiscent of an old farm house or barn. It's thought that patterns with sharper bends look more modern and have more strength due to the flat part of the metal sitting flat against the boards. The idea is that you have to screw a flat piece of metal to a flat board to get it snug, and if you go through the peaks you'll just smash the peak down and create a leak. Either that or it'll bend the screw back and forth due to expansion and contraction due to it not being snug.

We have all sorts of reasons why the design in that video won't work, but as you say, it does work. It works across an entire continent. You say it lasts for "many years" but how long is that? 25 years?

Generally I would expect a steel roof to look in great coondition for more than 25 years.  I would expect them to last for 50 years, but they may get a bit faded (the colorbond ones) by that time.  They shouldn't leak unless serious rust has set in, which is obvious to the eye.

The peaks are not pulled all the way down, but just "tensioned" by the screw.  That way the screw allows for a little flex, but never letting the steel get loose.  It is used everywhere in Australia, partially because it is cheap to transport and easy to install on site. 

Probably one proviso is to walk on the screws, that is where the wood underneath gives it strength.  If you walk in between the wood, you will bend the steel.

@lthenderson our rainfall in Australia is incredibly varied.  While my capital city Melbourne gets around 650 mm, I live only 40kms out of town and we get  1050 mm per year.  When I lived in Geraldton, an average year was 250 mm, but a "good" year was 650 mm.  Parts of nothern Queensland get over 6000 mm per year.  Steel roofing is used in all of these locations, and in fact is preferred as you go to norther Queensland as it ie easier to make safe from cyclones.


Our roofing choices are usually heavily influenced by "what is normal".  The idea of using asphalt on a roof is so strange to an Australian and I have only ever seen it used once, on a very old shed I was removing in the early 1980's.  We have the choice of tile (cement or porcelain) or steel.

lthenderson

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Re: DIY Roof Replacement -- Metal over Ashphalt
« Reply #46 on: Today at 11:52:29 AM »
@lthenderson our rainfall in Australia is incredibly varied.  While my capital city Melbourne gets around 650 mm, I live only 40kms out of town and we get  1050 mm per year. 

Yes, I'm aware but at 1050 mm per year, half of our states still get more rainfall. Our wettest state, Louisiana gets around 1525 mm per year. Throw in hurricane events and you end up doing things a bit differently when it comes to making things rain tight.