Author Topic: I have a rooftop patio leaking water into the level below...What should I know?  (Read 5909 times)

Aardvark

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I just bought a house. It is a townhouse in a development with a bunch of similar houses. There is a known issue that many neighbors have experienced too - moisture leaking from the patio into the level below. There seem to be two known sources within 6 feet of each other. The one source is the door leading to the patio - aparently these doors do not have flashing (or adequate flashing). The other source is a ventilation shaft that airs out the floor of the top level / ceiling of the level below. Both of the sources are easy enough to fix, and we have budgeted for that, but I have a few questions:

1 - How do I make sure that there isn't another source?
2 - How do I detect all existing water damage and make sure that all water damage (and potential mold - god forbid) is addressed.

3 - more specific question: Why are there so many different types and prices for humidity meters? Any recommendations on what to get that is accurate and reliable but not overkill for a non-professinal handyman? These things range from $15 to $1k. Also - what is the difference between a pin and a pinless meter?

ChpBstrd

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1) Visual inspection of the topside is probably your only option here. Also see #2.
2) If you want to be 100% sure, the ceiling of the lower level needs to come out. This might be a good opportunity to put in something easier to inspect and repair, like tastefully done hanging ceiling tiles. Think ahead, because rooftop patios are inherently troublesome. Do this before attacking the top side of the project, because you will likely find hidden damage that could change the scope of the project.
3) This question is outside my expertise. Generally, if you do #1 and #2 it is likely you will immediately see where the leak is. It seems unlikely that a moisture source would not stain the wood within a couple of weeks, and would only be detectable with a moisture meter.

sonofsven

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1) "Think like a raindrop". Where can water come from? Where can it go? Where does it accumulate? Use a moisture meter on the ceiling below to try to map out areas of higher moisture content. What happens with leaks, generally, is the insulation gets wet and is slow to dry in an enclosed space like a floor/ceiling. The wetness of the insulation will lead to wetness on back of the drywall.
Now this only tells you so much, because one leak can soak a lot of insulation, but it can tell you generally where the problem areas are, like the south wall, or the west wall, etc.
Where does the wind driven rain generally come from in your area?
Also, penetrations. Any penetration in the (supposed) waterproof floor/roof/etc is suspect. Deck railings and posts, for example.
Also, how is the patio constructed? Is it a torch down membrane with a wood or paver wear surface, or one of those roll on "waterproof" membranes? I would be suspicious of the latter


2) The best way is to remove the floor entirely, remove any rotten framing, wet insulation, etc, and rebuild it. If it has leaked long enough this is the only option. I have custom stainless pans built for all exterior doors that aren't covered by a roof, and if I'm near the ocean where we have strong wind driven rain these doors get pans even if they're under a roof. I'll put 30# felt (tarpaper) below the pan, the same 30# felt over the sheathing vertically (cut into long rips around 8" wide) that lap over the pan, install the door, then another layer of felt over the door flange. This is for a slider, a swinging door is done with one layer not two. The pan is constructed with a short vertical plane (1/2") on the sides and towards the building interior, and it laps over the stainless flashing or vertical part of the torch down membrane below. You work from the bottom up so everything laps properly, again "think like a raindrop". You wouldn't believe how many times I've torn apart walls and found the lap done backwards.
The second best way is to remove the ceiling below, but this obviously doesn't address the issues in waterproofing above, but sometimes it's necessary to asses and repair any damage. The problem here is that often a leak above will show itself in a different location below. Another issue is that it creates a big mess in the living area.


3) I have this one https://lignomatusa.com/product/mini-ligno-ed-pin-moisture-meter/   I have been happy with it. I use it on wood to determine moisture content, in drywall to try to follow leak patterns behind the walls, and firewood.
You can take a deep dive on the differences but the bottom line is they both work. I prefer the simplicity of the pin type, personally. I trust them more, which is fully subjective. I also use it more as a "relative" tool, as in, what is the MC in this area, or this board, compared to that area or board when trying to chase leaks.

Finally, these types of porches, decks, etc over a living area are problematic. I build on the coast so they're really problematic. If they don't have roofs they're even more problematic. It's not just the floor waterproofing that has to be done right, the walls do, too. Any mistakes in the wall plane can get right past the "perfect" floor waterproofing and show up in the ceiling below. I would consider them like a roof, with a life expectancy of 30-40 years if theyre done right. And so much of what I've seen in modern townhouse/condo construction is far from "done right" in terms of exterior details.

Aardvark

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Thanks both - great answers.

We are working with a contractor that we have reason to trust, but intend to ask questions and be critical. We also plan on contributing a lot of labor to keep costs down as far as possible. We have budgeted to do the following work (with a bit of wiggle room in the budget):

Patio:
 rip up the pavers on the patio to determine what's beneat (torch down membrane vs "waterproof" membrane)
- replace rotten siding on the patio (rodden due to bad drainage resulting in pooling)
- redo the waterproofing/roofing component of the patio. This includes (1) installing a new membrane (any help on what exact membrane to use would be great), (2) ensuring adequate flashing under to patio door, (3) ensuring adequate moiture management / sealing / drainage around the attic vent.
-install Trex decking on patio

Ceiling below the patio:
-Rip out as much ceiling as necessary. Start at known moisture intrusion points (As determined by moisture meter and visible damage) - Work outwards until no more signs of water damage.
-Assess damage once ceiling and insulation have been removed (hopefully no mold).
-Replace wood as necessary
-replace insulation and ceiling


While the patio floor is exposed, and also while the ceiling is open we plan to "think like a raindrop" @sonofsven - honestly, I have been taking this approach very seriously!

My biggest fear is that we go through all of this and then during the next big rain storm we find new moisture intrusion in the ceiling! ... Do I just have to trust that between myself and the contractor we can do this right and solve the problem? Or is there a good way to test before we finish the job? I've been thinking of putting a sprinker on the patio for a few hours while the ceiling below is still open. Then we could conceivably detect a leak before we close up the ceiling... But that also seems a bit sily because surely if we do a half decent job on the patio it shouldn't leak immidiately afterwards?!

@ChpBstrd ... I feel as though I am potentially over thinking things rather than not thinking ahead enough, haha.

Aardvark

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Two key pieces of info to add...
1 - The patio is like 400 sqft - so this is not the biggest job in the world. But I really want to do it all "first time right" and sleep easy for the next decade or two if that's possible.
2 - I have limmited DIY skills, especially with drywall and wood framing. In my home country everything is brick/cement. BUT - I studied engineering and I am pretty compentent when it comes to hands on and technical things. I think I can learn pretty fast, and I am confident in saying that I am willing to work bloody hard. Also looking forward to learning along the way.



ChpBstrd

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There is a case to be made that you could simply replace/recover the roofing material and siding, and be done for a long time. The question in the OP though, was how to ensure there is no hidden damage from leaks. Thus the amount of work to be done relates to your tolerance for uncertainty.

If no uncertainty can be tolerated, take down the entire ceiling in the room below and look for stains on the wood. Then replace all damaged wood. New sheetrock could be professionally installed for about $1k or you could go with the hanging ceiling panels l suggested.

If some uncertainty is OK, just peel up the pavers and stomp around looking for soft spots. If there are no soft spots, just install new roofing.

I suggest getting quotes from commercial roofing companies with experience in flat roofs. They can evaluate if the slope is sufficient and may have better products to solve the problems with doors and vents. They may also have good ideas about how to install a surface to walk on. Some such companies may package any carpentry work with their bid, which would relieve your anxiety about experience. To them, it might be a minor task to be expected.

Aardvark

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I suggest getting quotes from commercial roofing companies with experience in flat roofs.

Thanks - getting on this right now.

sonofsven

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Yes, find a roofer experienced in torch down roofs. It doesn't have to be a commercial roofing company.

Dancin'Dog

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I'm dealing with a similar problem.  Our balcony patio, that's covered in stamped concrete, leaks onto the downstairs patio below.  The ceiling is vinyl siding material, so it won't to too difficult to remove for inspection.  We haven't noticed any water intrusion, so hopefully it's only an exterior problem.


This thread has reminded me that I need to remedy this ASAP. 


@Aadvark good luck with your leak & thanks for asking about it here.

tallpines

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Great question OP,
I encountered the same problems on two rooftop patios this summer.
One was the floor drain wasn't connected to the drain pipe in the floor framing so water went in the drain and directly into insulation etc.
Second was a lack of flashing on top of the parapet walls so water was allowed to get behind siding and it went downhill from there.

If you send some pictures or take a video I may be able to help further.

Aardvark

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OKay - here is an overdue update... This has turned into quite the wild ride...

First of all: A few roofers came for quotes and said that they would want to lift one of the pavers to see what's underneath before they finalized a quote. The one guy came back with a hammer to break and lift one of the pavers. 10 minutes, and about 1000 hammer-stikes later, we realized that these were not pavers... Instead of pavers we have a 3 to 6 inch thick concrete slab that has been scored to look like pavers... So, somebody thought that pouring a 5 inch concrete slab on a third-story rooftop was a good idea.

To save some cash I went to Home Depot, rented a breaker, and did the demo work myself. Was hard work, but a great expereince. Once the demolition was done I thought that the hardest part was over... But it turns out that lugging concrete rubble down three flights of stairs is way more work and the demolition. So, we found a reasonable quote and had some people do the heavy lifting for us.

Under the concrete slab we found a PTO membrane. It was in relatiely good condition (except for where I had nicked it during the demoliition). This has me convinced that the membrane was not leaking, and that the water was coming in at the perimeter of the membrane - probably under the handrailing.

One of the roofers has totally won me over, and I've accepted their quote to rip off the old TPO membrane and put in a 60mm EPDM membrane. While they are doing that they will assess damage and replace any sections that have significant water damage.

The next big question is what I should put on top of the EPDM mebrane to make the patio walkable.
I am not planning on pouring 5 inches of concrete on top of the EPDM... I think I want a paver system, but the quotes that I am getting are surprisingly expensive (liek $10k for a 400 sqft patio). I'd appreciate any suggestions. I might also make a post in the DIY section of the forum.

ChpBstrd

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Any reason not to just lay down the $2/sf concrete pavers they sell at Lowes or WalMart? I wonder what your roofer would say about that.

bluecollarmusician

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We have a wood deck over a roof as you describe;

In short- there are "sleeper" 2x4's that lay underneath regular treated deck boards.  Underneath the sleepers are little rubber "feet"- basically just thick rubber pieces- (maybe 1/4 inch thick 2/2 square pieces laid approximately every foot or so- like 5-8 of them per 2/4/ sleeper) to lift the 2/4 sleepers- a)so that they (the wood sleepers) are not in direct contact with the rubber roof, and b) to enable a bit better drainage of water.

Then a regular deck is installed on top of the sleepers.  So the deck is not attached to the roof.  We live beach front and are prone to very bad winds and storms at certain times of the year and have had no issues with this.  It seems to be common practice.

This would likely be much more cost effective that the solution you are describing, and it is fairly easy to take any deck boards if you need to get to the roof underneath.  I understand this is a relatively common method for this type of deck.  Your deck is quite a bit larger than ours (our is maybe 250-260 sqft?) and the quote for the type of deck you describe sounds about right.

I would suggest considering composite material for the sleepers, and then keep the deck boards stained and you will have a deck that should last as long as the roof.


I should mention this could be a DIY solution.  Main thing is doing a little research to get some good rubber for under your sleepers, and don't puncture the roof when screwing in your deck boards :-)


« Last Edit: January 28, 2024, 03:49:40 PM by bluecollarmusician »

bluecollarmusician

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Whatever you end up doing, please let us know!

I am curious, and also wondering about approx. cost /sqft for the new rubber roof.  We have a few, and a couple may need replacement soon...

sonofsven

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Do you have an HOA? There might be rules on what you can install.
I've built wooden sectional decks similar to what bluecollarmusician described, with torch down roofing on the sleepers, and the deck sections small enough to pick up and clean under (but nobody ever does as far as I can tell).
I've seen pavers, too. I believe you can get them with a grid/support type of system, but I have not done them myself.
The way you're going about it is the right way, in my opinion. When in doubt, rip it out.
Penetrations in the roof membrane are always the most likely fail point, the next being the roof to wall transition and/or the door, so take care in those areas.
Make sure to remove enough siding to get nice new flashing installed over the membrane up the wall.
Hopefully your dream roofer has a carpenter they can call if needed. As wonderful as roofers are (?), they aren't carpenters, even if they think they are.

Car Jack

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We have a near flat roof outside some floor to ceiling windows.  Lots of water problems.  We've learned a lot and when we can find a contractor are going to make changes that won't work for you, I don't think.

1: Water comes in between the windows or through the wooden trim frame pieces.  Driving rain comes in and when the house was painted, pressure washing made water come in.  What you can do is have the windows/doors going out to the deck checked.  You could spray in with a garden hose and see if everything is water tight and if not, replace.  Have someone knowledgeable who will probably shake their head Yah when you tell them water comes in. 

2:  Water comes into the joint between the windows and roof.  For now, I've gorilla taped thick plastic on the lowest foot of the windows all the way across them.  This greatly reduces water coming in during driving rain.  But when speaking with a contractor, it was discussed that if we increase the pitch of the roof, that will help greatly.  So our floor to ceiling windows will have a 2 to 3 foot wall at the bottom and that'll start the pitch of the roof.  The current roof tilts maybe 2 inches in 10 feet.  Likely, your patio is similar.  When we had the roof redone about 3 years ago, we first put down new rubber membrane as it used to have white stone on top.  We decided in the middle of the job to have rolled roofing installed that matches the rest of our roof.  But even with the membrane with rolled roofing over it we get water but I believe it's probably all from the joint of the roof and windows.

Do you need and use the patio?  If not, you could likely do what I'm doing.  Lose the patio, gain a roof and smaller windows with a wall. 

Ask others who have solved the problem what they did.  That could help a lot.

Aardvark

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Thanks everybody, a few answers below:

@ChpBstrd - We could do pavers, but we would need something between the pavers and the membrane. traditionally people would do a "mud bed" with a drainage mat and some other shenanigans. I am hesitant to go that way because I want to be able to access the membrane relatively easily if necessary. These day's people seem to use a rubber pedestal system similar to what @bluecollarmusician described.

@bluecollarmusician - I have seen very fancy rubber pedestals used to support a decking system on a membrane roof, but I have noot seen what you are describing which seems like a very sensible DIY version of this: https://duradek.com/plazadek/floating-deck-system-applications/pedestal-systems/
I will definitely look into this. Regarding cost per sqft - the prices had a much much wider range than I was expecting. Some included a walkable finishing and some didn't. Some included the carpentry, and some didn't. In the end we decided to work with different groups to do the different tasks. The roofer that we wanted happened to submit a cheap quote for the roofing membrane. The carpenter we wanted submitted a decent quote for the roof work combined with some other work that we needed done. The one thing remaining is that we need a walkable surface on top of the membrane.

@sonofsven - we are working with a carpenter on this job. Our HOA has approved the project, but that thanks for adding this consideration. You said to have "flashing installed over the membrane up the wall"... but my understanding is that the membrane will simply be extended up the wall and act as flashing - with the siding being installed over that. Does that make sense? Or should there be flashing on top of the membrane befre we cover it with siding?

@Car Jack - MANY of our neighbors with a similar design are having issues with the flashing under their patio door. We have asked the roofer to spend some time and effort  (and if necessary money) on ensuring that this problemis solved. We definitely want to use the patio - it's a great addition to the house.

I have two new insights:
1 - I should get more quotes from solution providers like Zach, but the DIY option seems achievable and I'll look into that too.
2 - There is no very obvious solution that I have been missing, and this is process of figuring out what I want, what I'm willing to pay, and what I want to do myself.

sonofsven

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Thanks everybody, a few answers below:

@ChpBstrd - We could do pavers, but we would need something between the pavers and the membrane. traditionally people would do a "mud bed" with a drainage mat and some other shenanigans. I am hesitant to go that way because I want to be able to access the membrane relatively easily if necessary. These day's people seem to use a rubber pedestal system similar to what @bluecollarmusician described.

@bluecollarmusician - I have seen very fancy rubber pedestals used to support a decking system on a membrane roof, but I have noot seen what you are describing which seems like a very sensible DIY version of this: https://duradek.com/plazadek/floating-deck-system-applications/pedestal-systems/
I will definitely look into this. Regarding cost per sqft - the prices had a much much wider range than I was expecting. Some included a walkable finishing and some didn't. Some included the carpentry, and some didn't. In the end we decided to work with different groups to do the different tasks. The roofer that we wanted happened to submit a cheap quote for the roofing membrane. The carpenter we wanted submitted a decent quote for the roof work combined with some other work that we needed done. The one thing remaining is that we need a walkable surface on top of the membrane.

@sonofsven - we are working with a carpenter on this job. Our HOA has approved the project, but that thanks for adding this consideration. You said to have "flashing installed over the membrane up the wall"... but my understanding is that the membrane will simply be extended up the wall and act as flashing - with the siding being installed over that. Does that make sense? Or should there be flashing on top of the membrane befre we cover it with siding?

@Car Jack - MANY of our neighbors with a similar design are having issues with the flashing under their patio door. We have asked the roofer to spend some time and effort  (and if necessary money) on ensuring that this problemis solved. We definitely want to use the patio - it's a great addition to the house.

I have two new insights:
1 - I should get more quotes from solution providers like Zach, but the DIY option seems achievable and I'll look into that too.
2 - There is no very obvious solution that I have been missing, and this is process of figuring out what I want, what I'm willing to pay, and what I want to do myself.

To clarify, it would be building paper over the membrane up the wall, with siding over the building paper.
Under the door, where the membrane has to be cut at the top of the curb, I have ss pans made that lap over the membrane and have a 1/2" vertical lip on the two sides and interior. That way if any water is hitting the door it drains down to the pan and over the membrane edge

Aardvark

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Okay... long overdue update incoming. Read if you're interested in hearing how this saga played out. I'll try keep it short, LMK if you have any questions.

There were three sections of work that needed to be completed:
1a - make roof waterproof (ideally patch/repair membrane, but replace it if necessary). This work will probably be done by a roofer.
1b - Fix trim and make everything look nice again. Cleaning up after the roofer was there. This would probably be done by a general contractor
2 - once roof is waterproofed, find the best (cost, quality, aesthetics) walking surface that will protect the newly repaired membrane and also allow us to use the patio.
3 - restoration work in the room below the patio. Replace everything that was damaged by water, identify and treat any mold, replace insulation and drywall, paint.

I got three quotes for each section of work mentioned above. The spread of quotes was wild. Some people quoted 5 times what other people quoted. In the end I went with the cheapest or second cheapest quote for all sections of work. I could not see any value being added by the higher quotes.

1a – this was a bit difficult to decide, but in the end the one roofer won our hearts over and also convinced us that he knew exactly what he was doing. We have no regrets going with him. In the end the membrane needed to be replaced. Luckily (extremely luckily) the water damage beneath the membrane was minimal and basically no wood needed to be replaced. This was our biggest worry – because we had no way of knowing how good/bad things would look once the membrane was removed. The roofer installed a 60mm EPDM membrane and re-did the scupper/drain to improve drainage a bit. He also raised the parapets (sections of wall below the handrailing) to ensure that we have sufficient space to work with. In the end the entire job was stress-tested by plugging the drain and flooding the entire patio with about 3 inches of water for about an hour. No leaks. Yay.

1b and 3– the same guy that is about to finish the remediation work (item number 3) is going to do the finishing work on the patio once the walking surface is fully installed. Luckily the interior remediation work went without hiccups too. I learned a lot during this process. I learned about how houses are built in the US. I learned about mold (luckily only a tiny bit and we treated it well). I learned about working with contractors – I think an itemized list of the exact work to be done would be my MO in the future. But in general things have gone well here.

2 – The roofers strongly recommended that we use a floating tile system as the walking surface as it would not compromise the waterproofing, it would enable us to easily access the membrane if necessary, and it would look goo and last a long time. The roofer actually seemed very hesitant to warranty his work if we did not go with a system like this. At first I thought that this was weird, but when I spoke to other roofers and also separately when I spoke to paver/tile contractors, literally everybody recommended this as by far the best solution. It is expensive though… But we decided that it makes sense if the priority is to keep the membrane in the best possible condition. The one other option that I considered was using a PVC vinyl membrane that is certified as a walking surface. The catch is that this membrane is almost as expensive as the EPDM + floating tile solution, and it also looks straight up ugly.

So.. In the end it has been three months of nail biting and project management, but the project ended up only slightly over budget, and I look forward to knowing that the patio is waterproof and that there is no mold in the walls/ceiling.
Thanks to everybody in this group for all of the advice. I wish I had posted here earlier because then I would probably have started working with a roofer earlier – thanks for that recommendation @ChpBstrd

All is well that ends well 😊



sonofsven

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Thanks for the update!
I'm glad you got the work completed to your satisfaction.
It reinforces why I don't build decks/patios over living space. Like any roof they need to be replaced eventually but it almost never happens until they've leaked enough to cause extensive damage. But as I've said, I'm on the rainiest of coasts so wind driven rain is the norm.
And as bad as yours was, it's even worse when your patio is leaking into someone elses unit.

 

Wow, a phone plan for fifteen bucks!