R40 blow in attic insulation? DIY?

[surfer349]

Looking for advice. I'm a moderately handy guy and wondering if this is something I could do myself instead. Experience = zero.

Zone 6b/7a. Idaho. hot summers and cold/moderate winters.

- R40 blow in attic insulation
- sealing attic floor with spray foam - sealing around all electrical, plumbing, penetrations.
- Duct sealing along trunk line in crawlspace.
- install 30W solar fan, thermostat controlled.
- install radiate barrier underneath rafters, over entire attic space.

Cost = $5260
Rebate = -$820
Tax Rebates = -$2104
TOTAL = $2336

[nereo]

This is absolutely DIY-able, and I’ve done it twice.

First, with your climate zone I wouldn’t stop at R40, but instead go all the way up to R60 (provided there’s nothing wonky about your attic that would prevent this).  The time difference between R40 and R60 is minimal, and the cost will likely be just a few hundred$ more, which will have a ROI on the order of a year or two (up to 50% less heat loss through your attic)

A few tips:
Have a helper, and use a two-way radio (or your phones) to communicate. 
Get and wear a disposable Tyvek suit with hood, and tape your suit to your gloves.  Get and wear a respirator (not just an N95 mask).  It will be very dusty.

You’ve got the basic order right - air sealing is paramount.  If you’ve got old-fashioned ‘can’ lights extending into your attic you can either build a dam around them or (preferably) replace them with sealed, integrated LEDs that will both save electricity and not leak air.

Mark the target depth with a sharpie on your rafters (probably ~18”)

Install rafter vents, and make sure you don’t block them

Plan how you will work, starting from teh far corner and then ending near your access point.

[secondcor521]

I'm probably a below average DIY guy in Boise.

I did R60 blow in in my attic DIY.  It's easy.  If you buy enough insulation from Lowe's, they'll let you borrow their blower for free for 24 hours.  I bought that much, and returned the excess when done and got a credit refund.  Seal things first, of course, which may require pushing around any existing insulation.  It's a two person job - you need someone in the garage loading the bales into the hopper, and then you need someone in the attic pointing the blower hose where it should go.  We set up some sort of communication system that I don't recall offhand between the attic person and the garage person, but that was also easy to figure out.

Attics are hot in the summer, and cold in the winter.  I did mine in October IIRC and that was just about perfect weather.  If I were in your shoes I'd be considering doing it in late March.

I haven't done a solar fan, but my BIL did one himself DIY.  He thought it was easy, and seemed pleased with the results.

I'm not sure I would do the radiant barrier at all.  It would be good in Idaho summers, but in winter it might be counterproductive.  Maybe someone else knows better on that.

[secondcor521]

Agree on the can lights.  My kitchen has floodlights, but they were rated to be OK to be in contact with the insulation.  You should check whatever you have - I think it's pretty obvious what is OK and what isn't.  If you already have can lights and existing insulation, there may already be dams around them.  If so, make sure not to get any insulation inside the dams.

I also bought some rigid foam insulating panels (maybe 2" thick) and attached them vertically around the perimeter of my attic up from where the walls were.  This kept the insulation over the house itself and allowed me to end up with insulation that was shaped like a cake rather than shaped like a pyramid or dirt pile.  It also kept it off of the eaves, which kept the vents clear.  You actually want the eaves to be free of insulation so they stay cold and don't create ice dams.

[Paper Chaser]

I frequently read posts from people that say this type of insulating is often a job that a pro can do just as cheaply as DIY.
It might be worth getting some quotes unless you've really got your heart set on DIYing this.

[uniwelder]

I frequently read posts from people that say this type of insulating is often a job that a pro can do just as cheaply as DIY.
It might be worth getting some quotes unless you've really got your heart set on DIYing this.

In the past I had professional quotes that were the same as just materials for DIY.  The last time, 1 year ago, the professional quote was significantly more ($1/sq ft for R-30), and I DIY'd it, but I ended up not getting the same fill (also likely because it compressed the original blown fiberglass underneath) amount as the bags of cellulose said it should cover.  Between buying extra material, paying a neighbor $100 for his time filling the hopper until my wife took over, and time/gas to pick up all the insulation, it would have been the same price to have just hired the professional. Also factoring in your own time, a professional might be finished in an hour or two, while it took me around 12 (including 2 hours driving for 3 trips) because the machine was so slow.

[surfer349]

You’ve got the basic order right - air sealing is paramount.  If you’ve got old-fashioned ‘can’ lights extending into your attic you can either build a dam around them or (preferably) replace them with sealed, integrated LEDs that will both save electricity and not leak air.

editing...
from doing some more research, it looks like I need to spray-foam seal the all the penetrations/lighting cans/electrical/plumbing/etc first, before doing the spray foam

1. seal w/ spray-foam all attic floor penetrations.
2. install 30w Solar Fan
3. Install radiant barrier under rafters
4. Install rafter vents
5. blow in insulation

is this correct?

[surfer349]

Agree on the can lights.  My kitchen has floodlights, but they were rated to be OK to be in contact with the insulation.  You should check whatever you have - I think it's pretty obvious what is OK and what isn't.  If you already have can lights and existing insulation, there may already be dams around them.  If so, make sure not to get any insulation inside the dams.

good points. Last year, I replaced all the can light bulbs with these LED retrofits.
(https://www.homedepot.com/p/Lithonia-Lighting-Contractor-Select-E-Series-5-6-in-2700K-Warm-White-Integrated-750-Lumen-LED-Recessed-Retrofit-Baffle-Trim-65BEMW-LED-27K-90CRI-M6/308370742)
think this is OK or the whole can needs to be replaced?

[surfer349]

Curious if anyone can comment on blow-in vs spray foam?

[nereo]

Curious if anyone can comment on blow-in vs spray foam?

That's a topic entirely in itself.  Spray foam isn't DIY (yes, they sell kits, e.g. Dow's Froth Pack, but for the quantity needed it's not price competitive unless you are only planning on doing a few hundred board feet).  Spray foam is also far more expensive and depending on the dispensing agents used may require you to be out of the home for up to 24h, and it's damn hard to remove/modify if remodels are in your future.  Spray foam has a much higher environmental footprint.
OTOH, it will form both an air barrier and a thermal barrier, and has the highest R-value per inch.

IMO blown cellulose is the perfect material for unconditioned attics.  It's cheap, low footprint, and can be professionally removed for not a ton of money (a couple grand), and you can remove sections of it yourself should you need to access wiring or install new lights or whatever. however, it is NOT an air barrier, which is why your first order of business is to seal up any air leaks between your conditions space (inside your home) and the unconditioned attic.

[secondcor521]

You’ve got the basic order right - air sealing is paramount.  If you’ve got old-fashioned ‘can’ lights extending into your attic you can either build a dam around them or (preferably) replace them with sealed, integrated LEDs that will both save electricity and not leak air.

editing...
from doing some more research, it looks like I need to spray-foam seal the all the penetrations/lighting cans/electrical/plumbing/etc first, before doing the spray foam

1. seal w/ spray-foam all attic floor penetrations.
2. install 30w Solar Fan
3. Install radiant barrier under rafters
4. Install rafter vents
5. blow in insulation

is this correct?

I'd switch the order on 3 and 4.  Your house doesn't already have adequate rafter vents?

I personally wouldn't DIY rafter vents.  Conceptually they are easy but cutting a hole in my roof makes me personally nervous.

[secondcor521]

Agree on the can lights.  My kitchen has floodlights, but they were rated to be OK to be in contact with the insulation.  You should check whatever you have - I think it's pretty obvious what is OK and what isn't.  If you already have can lights and existing insulation, there may already be dams around them.  If so, make sure not to get any insulation inside the dams.

good points. Last year, I replaced all the can light bulbs with these LED retrofits.
(https://www.homedepot.com/p/Lithonia-Lighting-Contractor-Select-E-Series-5-6-in-2700K-Warm-White-Integrated-750-Lumen-LED-Recessed-Retrofit-Baffle-Trim-65BEMW-LED-27K-90CRI-M6/308370742)
think this is OK or the whole can needs to be replaced?

I'm not going to answer your question directly as I don't want to be partially responsible for you potentially burning your house to the ground.

What I would say is that if I were in your shoes, I'd figure out what type of insulation I were going to use (I used the white blown in stuff from Lowe's), look at the rating on my kitchen lights, and confirm to my own satisfaction that the combination of the two wasn't going to ignite.

The people at the Lowe's or Home Depot contracting desk might be willing to give you their opinion, but it's still your house.  It might be a bit unfair, but if you had a professional out for a quote you could ask them about this as part of their estimate.

[secondcor521]

Curious if anyone can comment on blow-in vs spray foam?

If you start diving into this aspect there are a multitude of options and opinions.  Each option has benefits and drawbacks.

I personally went with the blown in (white stuff at Lowe's), based on cost/sqft, ease of insulation, weight, and what I already had up there.

The whole project cost $932 in October 2020.  I was also able to take a federal residential energy credit of 10% on line 19a of Form 5695.  But the Inflation Reduction Act might have, and probably did, change the rules for residential credits.  Idaho also has some energy efficiency tax deductions on about line B-4 of Form 39, but in 2020 those did not include insulation; I don't think Idaho tax law has changed in that regard.

[chasingsnow]

PTF were thinking of buying a place in the spring and insulating the attic on the old houses in our mountain town will be at the top of the list

[snic]

A 30 watt solar fan will likely be completely useless. A relative in the HVAC business once described a similar set up as "shoveling shit against the tide": the rate of heat build up is enormous relative to the rate of hot air removal. In addition, attics are *supposed* to be hot. If you properly air seal and insulate up to R60 or beyond, that will be far more effective in keeping your living space cool in summer than installing an attic fan.

[Paper Chaser]

Curious if anyone can comment on blow-in vs spray foam?

Closed cell spray foam will insulate and air seal at the same time, but it's costly. You can spray the floor of the attic, leaving the attic vented, or you can spray foam the whole attic, fully sealing it up and adding it into your HVAC envelope. This can have advantages (conditioned storage space, any utilities in the attic will tend to last longer due to being kept in a more constant temperate environment, etc) but it will need to be fully sealed from the exterior (no venting of any kind) and may require different HVAC sizing because you're potentially adding tons of volume to the building HVAC envelope.

Cellulose is easy to DIY, and has very good R value for the money. But it takes up lots of space and doesn't air seal.

For new construction, fully sealed attic with spray foam might be the best option. For retrofitting existing buildings though, I'm less certain. If you wanted the best of both worlds in an existing home, it might make sense to spray foam 2-3" thick on the floor of the attic and then blow in insulation on top to provide the bulk of the suggested R value with less expensive insulation. This would give you great air sealing and R value, but no easy storage in the attic. Rigid foam panels 8-10" thick under some plywood subflooring would give you plenty of r value while letting you store things in the attic but would be costly and time consuming as well. To save on cost, you could do this only in select areas, and then blow in cellulose anywhere you didn't want/need storage.

[Papa bear]

Everything you ever wanted to know, and more! About attic air sealing can be read here. 

https://www.buildingscience.com/file/5862/download?token=f1mfZVf6

It comes complete with pictures on best practices for recessed lights, electrical boxes, chimneys, duct boots, etc.   


Sent from my iPhone using Tapatalk

[nereo]

Everything you ever wanted to know, and more! About attic air sealing can be read here. 

https://www.buildingscience.com/file/5862/download?token=f1mfZVf6

It comes complete with pictures on best practices for recessed lights, electrical boxes, chimneys, duct boots, etc.   

Fantastic resource @PapaBear - thanks for posting that

[Jon Bon]

What is in your attic now? I feel that all this talk about IC fixtures would be moot if there is already insulation touching everything. Were you planning on removing, or going on top of existing?

Re: spray foam - costs a fortune, I DIY-ed it. Slight learning curve but I am mostly happy with the results. It is fantastic product but really is only worth it in an area if you don't have the space for more traditional materials. I was insulating between rafters, I did not have 20 inches of space for cellulose, so foam is more efficient per inch, so I used that.

Fan, radiant barrier and rafter vents are likely unnecessary.

Fan - as other said its small, and attics huge, not to mention they are suppose to have cold (intake) and hot (exhaust) vents so it naturally vents itself.

Radiant Barrier - why would you do this, your attic will be hot/cold which is fine because you will have r60 between you and the elements.  I mean I guess it might help your attic stay slightly cooler? but does not feel needed. It would be a lot of work for little benefit IMO.

Baffles - Maybe, they can be needed, and useful. But go into your attic and try to block the area of your soffit to your rafter, its impossible to reach, and nearly impossible to get cellulose into it. And even if you do block it up, that stuff is going to quickly settle. Even and inch of clearance would be enough. Furthermore the cycling of air thru your attic is going to further move/settle the cellulose. I put them in my attic, pretty much wasted effort to keep an airgap between the cellulose and the roof decking.  That happens pretty much on its own, so no baffle needed.


The worst part of being in the attic is moving around, it SUCKS no where to put your feet, nails from the roof cutting into your head, crap in the way, low ceiling etc etc. So I would avoid it as much as possible. I would pull all my lights/vents and fill in gaps from below. Likely easier than from above. So the best part of cellulose it likely you can spread it over the entire attic from only a few different (comfortable) positions!

I would for sure DIY, it has a massive bang for your buck.

[StashingAway]

As has been mentioned.

Nix the solar fan. Doesn't do anything more than a properly vented attic does. Spend extra effort making sure your soffits are over vented, and make sure the insulation doesn't plug them so that the natural convection of the hot attic can wash the roof with air.

Nix the radiant barrier. Not necessary for the way attic functions. Radiant barriers are marketed heavily but don't pass the sniff test (or scientific studies for that matter) in most of their advertised uses.

The building science man himself giving a good summary.

https://www.greenbuildingadvisor.com/article/lstibureks-rules-for-venting-roofs

[StashingAway]

Curious if anyone can comment on blow-in vs spray foam?

Spray foam in this use case isn't a continuous layer of insulation. Rather, it's little cans of foam that are used to seal up little holes. Similar applications that you would use caulking. The idea is that you crawl around in your attic and seal up all the penetrations between your roof space and your house space. Holes where electrical wires run, seal plates where drywall meets ceiling and air can leak in the wall cavities, etc.

This way any pressure differential between your roof and house space doesn't persuade air to mix.

Spray foam as a continuous application must be carefully managed in a retrofit scenario and isn't a plug and play replacement. It is usually applied to the roof deck rather than the ceiling space. You must make sure you aren't creating vapor barrier sandwich issues or otherwise letting exterior air into the new conditioned space. Lots more details to manage with a good building scientist.

[jeromedawg]

I've been deliberating this very same thing for the past year. We just had our HVAC system replaced and now it's time to think about insulating the attic. We currently have R19 up there and it's also pretty dirty up there as well (with some prior rodent droppings... no current signs as of today AFAIK). In my case, I would be looking at cleaning/sanitizing, removing and disposing of the existing insulation (other option is to just clean it up, reinstall it and supplement with more), air sealing, rodent proofing and then either considering batt insulation or blowing in cellulose. Blown in fiberglass is another possibility I suppose but last I checked I don't think there was availability in my area.

In my case, I've been wrestling with DIY because our attic is oddly shaped with angled trusses and beams all over the place. It's very tricky to navigate. Some parts of the roof are quite high up but there are parts where it gets extremely low and you pretty much have to get on your belly to access the insulation. To make it even more complicated, there are 'overhangs' at the edges where there's a soffit vent that you can't see (unless you want to belly crawl to the edge of the overhang and look down...) - blowing in insulation you risk blowing it over the edge down into the overhang and blocking the soffit vent. It's a horrible design and I'm not sure why they built it this way... with the amount of space up there, the attic has so much potential (beyond basic storage, even a potential room addition/conversion) but you can't do anything because of all the supporting beams :T The other thing is that I'd want to install some footing up there like planks or plywood for navigation, otherwise it would be extremely difficult (and dangerous) to try to navigate up there later if we have cellulose blown in.

Anyway, at this point, I'm wondering if we should just keep the R19 insulation and try to just vacuum/clean up, air seal, rodent proof (this is going to be difficult too because of how narrow of a space it is to access the edges from inside. There are also areas where it's kind of a steep angle to get down to where there are openings), and then add more insulation (I don't know which would be most beneficial: supplementing with more batts vs blowing in on top). Or if we should just trash the R19 and do all the rest but blow in cellulose. I don't think this is something I'd be able to complete in a couple days let alone a week, unless I took work off or something! I've gotten several quotes and they range from as low as $2000 (the guy said he would just clean my attic, no additional insulation installed though as he didn't think it's necessary, which was questionable to me) to $12k (these guys were a joke and totally were trying to rip me off and desperately tried to reach out to me for weeks after the initial estimate... I just ignored their calls).  If it were just the insulation to blow in, I'd be much more inclined to DIY but it's the clean-up and prep-work (especially air-sealing and making sure I get *full* coverage especially in the tight spots) that concerns me... the problem is that even if I hire it out, after seeing what's up there, it's hard to trust that anyone else would be more thorough :T

I'm in SoCal Zone 3 btw... I sounds like the recommended amount to supplement is R25 to R38. Otherwise, I'd want to aim for R30-R60 insulation. Per Google, that translates to anywhere from 8-16" of the blown-in cellulose.

Here are pics of what I'm talking about...

[StashingAway]

If you are going DIY, I personally would remove all of the insulation and dropping etc, then take your time to clean up the attic. Not sure if you're on the coast or inland, but pick a window where you have a couple of months to run up and down there where you're not running HVAC very heavily. Clean up wiring, get soffit baffles stapled, air seal, etc. when you're not rushed.

It would be much easier in a small space to try to have all of the insulation removed than tryign to shuffle it around with foam and caulk and trying to keep track of roof penetrations and completed bays, etc.Then just blow in new stuff. As long as you're doing the job and not on a budget, it won't be much more to just throw in a lot more cellulose.

[jeromedawg]

If you are going DIY, I personally would remove all of the insulation and dropping etc, then take your time to clean up the attic. Not sure if you're on the coast or inland, but pick a window where you have a couple of months to run up and down there where you're not running HVAC very heavily. Clean up wiring, get soffit baffles stapled, air seal, etc. when you're not rushed.

It would be much easier in a small space to try to have all of the insulation removed than tryign to shuffle it around with foam and caulk and trying to keep track of roof penetrations and completed bays, etc.Then just blow in new stuff. As long as you're doing the job and not on a budget, it won't be much more to just throw in a lot more cellulose.

The wiring is kind of nuts in there. Some of the runs feel kind of tight and are definitely not secured down (they're just running across the top of the insulation rather than routed along the joists, etc). I'm on the coast so now is an OK time to do it as it's cool up there... except if the attic is bare without insulation overnight that could result in the heater running longer. As far as the soffits, the right-most picture is what mine resemble except that yellow piece of insulation they have in that picture, which appears to be 'blocking' the cellulose - we don't have anything in place to block any cellulose from falling down into that space so I'd imagine we'd need to do something similar? It's a really tight squeeze to even get into that area though (with roofing nails penetrating from above) so I'm a little apprehensive about it hahahaha.

[StashingAway]

You don't have to get very far to the edges to install soffit baffles. You can just staple them on the peak side of the roof so they don't slide down, then toss a fiberglass plug at the base to keep the blown in insulation from packing in the overhang. It's not a big deal if some cellulose makes it's way past, you just don't want the holes to get filled. It's not very fun with roofing nails poking through, but it's manageable as a DIY.

https://www.youtube.com/watch?v=y69x6UJVkxk