I really don’t have a question. Just sharing an interesting day.I looked at a nightmare house yesterday, and I came away thinking that this is what not to do.
This is a cold climate. The house has a flat roof (EPDM), insulated with spray foam directly on the underside of the roof sheathing. I believe the foam is Icynene.
The EPDM roof was poorly designed and poorly detailed so there have been minor leaks. The main roof is OK, but there are these parapet walls capped with coil stock, and the roofer did not seal the joints in the coil stock. Trouble is, these minor leaks resulted in moisture trapped between a double vapor barrier (spray foam and rubber). I’m thinking if that rubber was yanked, it would be a moldy, perhaps rotten mess.
The other thing I noticed was that it was hot upstairs in the house. I could feel heat radiating from the ceiling. If you listen to spray foam advocates, you’d think that this couldn’t be possible. But if you have blazing hot black rubber on top with no air space, more heat will transfer through the foam, miracle product or not. Also, if this spray foam job was like others I have seen, there are thin spots.
The long and the short of it is that ventilation is cheap insurance. Maybe the trapping moisture thing is less of an issue with shingles and felt, because they are breathable, but roofs have a tendency to leak at some point in their lives.
Also, I know the foam salesman, and I can just picture him selling the builder on the wonders of spray foam and how it can just be sprayed on the underside of the roof sheathing.
Foam is a great product. But it is not such a miracle product that you can ignore basic building science. And like so much of construction, it comes down to the judgement of the dude with the foam gun (or the saw, or the nail gun or whatever)in his hand.
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The long and the short of it is that ventilation is cheap insurance.
For leaks?
For incompetent hacks?
Not.
Joe H
So your roofs last forever? How can you guarantee that the roof will NEVER leak. As far as I know, all roofs wear out and need to be replaced. And what if the next roof that goes on the house is put on by a hack? Seems to me that a system that does not completely fail if a little moisture get sto the roof deck is not a bad thing.
You describe a poorly designed roof, done by hacks and insulated by hacks and you think venting it would fix what?
Venting would seal the joints in the coil stock?
Venting would somehow alleviate the heat transfer through thin areas in the foam?
Not.
Poor design + poor workmanship = problems.
Joe H
Edited 6/26/2008 9:06 pm by JoeH
LOL.... Joe, you make some great points.... but people stopped saying "NOT" like 15 years ago!View Image
Hey, I'm 59, not 19.
BS is BS though, leaks are leaks and vents won't cure that.
Hell, farting would cure my gray hair if that was the case.
Joe H
LOL.... I'm with ya bud. BS is, was, and will always be BS. More to the point... I agree that there's simply no substitute for doing something the right way from the begining. Everything else is a cover-up or a compromise.View Image
Quit picking on us old farts. We just learned to start saying it a couple years ago and now you tell me it's passe`?I oughta kick your skinny little butt.NOT;)
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Thanks for the laff Diesel. That was funny. NOT! LoLYou knothead you. Bob's next test date: 12/10/07
Here's the thing. I was around when this house was built. Didn't have anything to do with it, but I know the project manager. He was (is) an engineer. He and the architect came up with the design. A local spray foam guy sold them on spraying foam directly onto the roof sheathing. I was skeptical, but I wasn't in a place to say anything. This is not the only job I have heard of where the "hot roof" has been pushed.Since then, our city building department will no longer approve unvented roofs. (correct me if I am wrong but this is now in the IRC). We gnashed our teeth about it on a later project. I even had a conversation with the foam contractor about it, and how stupid he thought the new code was. Now after looking at this mess, I see the logic.True, the roofer was a hack. It was a stupid design. But no roof lasts forever and some roofs are going to leak before you realize its time. So yeah, the idiot put a bad roof on and it leaked within three years. But how different would the story be if it had made it 30 years? Just a longer time before bad trouble, IMO.I've done my share of reroofs and I would say most old roofs I have seen have leaked at one time or another. I think it is folly to think that somehow we are so good these days that roofs aren't going to leak someday.Ventilation would not solve everything. But look at this situation. What really needs to happen is to yank the rubber and redo it right. Trouble is, the sheathing is wet, and there is no way for it to dry. So you can't just glue a new sheet of rubber down. Replace the sheathing? It's got all that spray foam stuck to it. At least if it was vented, there would be an opportunity for drying.Be interesting to know what was behind the code change to no unvented roofs.
"So yeah, the idiot put a bad roof on and it leaked within three years. But how different would the story be if it had made it 30 years? Just a longer time before bad trouble, IMO."Totally wrong thinking there. Any fool can decipher when a roof is wearing out, getting near the end of it's life expectancy and needing replacement. Failure to change the tires on your car or the oil in the engine can have disastrous consequences too. Expensive ones. Sometimes deadly ones. "Be interesting to know what was behind the code change to no unvented roofs."I can answer that. It was poorly insulated roof systems built in the seventies. That and the attempt then in the first oil crisis to do all sorts of things to seal up and save heat energy in older homes. The catch all answer to poorly done work was to require venting in all roofs.Thanks to newer studies done by the polyurethene foam insulation folks, mostly at Corbond, a lot of places are overturning that requirement.It all has to do with managing interior air quality and nothing to do with roofs leaking.
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"Totally wrong thinking there. Any fool can decipher when a roof is wearing out, getting near the end of it's life expectancy and needing replacement. Failure to change the tires on your car or the oil in the engine can have disastrous consequences too. Expensive ones. Sometimes deadly ones."Yeah, but you can easily see your tires. Or you can bring it in to Tires Plus and they can tell you. Hard to do with a rubber roof. This roof you can't see from the ground, and the HO doesn't even have a ladder capable of reaching the eave on the easy side. Sure you or I can keep track of our roof's condition. But can everyone? Mind you, I'm no big fan of flat roofs.Well, time will tell us the long term survival of spraying foam directly against roof sheathing. I'm thinking there will be a lot of rotten sheathing out there some day, with no easy way to change it. Just my opinion.
come on man, be real! You can't just automaticaly SEE your oil either. You have to make a n effort to pop open the lid, pull out the dipstick, clean it, re-insert it, and take a reading on how full and how dirty it is.
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But a house is also supposed to last a lot longer than a car, which is basically a disposable commodity. My own house 95 years old. It's had multiple owners, some good, some neglectful, etc. It's had some decent work done to it, and some real hack work. But it it still structurally sound after all this time. I'm not sure some of the structures we build today are going to handle all the mishaps that are bound to happen in the course of a hundred years. Heck, I have doubts about the tyveck-OSB-poly vapor barrier wall in terms of long term survival.I titled the thread "what not to do" for a number of reasons. I really didn't mean to focus solely on foaming against the roof deck. I don't really like flat roofs, especially on 2 story houses built on a steep hill. Lack of overhangs is another thing. And then whoever made the decision to hire the roofer made another mistake. As was spraying foam direct on the roof sheathing. But that's just my opinion.
everyone has opinions.Mine is that you are working hard to argue in favor of supporting bad practices with overkill on other areas.
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My take on it is that bad things are going to happen to a house throughout it's life. You can't control that. Hacks will work on it. Mistakes will be made. A bit of overkill isn't a bad thing.
Here's the thing
Venting won't fix this mess, venting will not stop the poorly designed & poorly done roof from leaking.
It's a tear off down to whatever hasn't rotted.
Joe H
Yep. And it would be a hell of a lot easier if the foam wasn't stuck on the roof sheathing.
Not convinced the foam is a problem ... moisture wise.
If you have identified that water got under the EDPM, then the issue is a leaky roof and 'correcting' a bad foam job won't change that. And you will still have moisture problems ... really only solvable in this case by removing the roofing and drying out the deck ... otherwise the moisture will stay there and destroy your roof deck/structure. None of the problem was 'caused' by the foam (exacerbated, maybe, but not caused). Adding foam and makng it more even may improve the thermal characteritics. The foam should be an effective vapor barrier (i.e. retarder) of moisture from the inside going out.
If there are issues w/ the water integrity of the roofing, you are forced to remove it and dry out and replace making sure the details are right. Tough choice, but really the only solution ... now watch ... someone will come up w/ a brilliant, simple solution.
Yeah just pull up the rubber roof lay down sleepers over existing deck with slight pitch to parapet walls ,redeck with scuppers built into p walls then reroof. If concerned about future leaks make new deck out of treated lumber.
ANDYSZ2WHY DO I HAVE TO EXPLAIN TO FRIENDS AND FAMILY THAT BEING A SOLE PROPRIETOR IS A REAL JOB?
REMODELER/PUNCHOUT SPECIALIST
I had the same thought--sleepers and a new roof deck. Only I was thinking of cutting the parapet walls off and have an overhang all around with vented soffit. The house has siding issues too. Then I could cut the old rubber away before I sheath the new.
I think Dieselpig would tear off the roof and put a second story on with a proper roof.
Well sure. There is the slight problem of paying for it.
That's always the problem!
If you are so unsure about leaks that you use treated plywood, you shouldn't do it. Treated plywood will survive the water, but you haven't solved the problem. I wouldn't waste money on treated plywood ... it's like betting against yourself.
Not only is a sole proprietor a real job ... if you actually make money ... consistently ... it is a dream job.
Plus treated plywood arrives soaking wet, weighs a ton, turns into a potato chip when it dries.
I have a flat roof on my wood shop/treehouse that I used treated 1/2" on top of 2x10's with 4x4 post as support under the seams. With a rubber roof .I can hangout up their but about every 5 years I will replace or patch from tree limbs so when it starts to rain in my shop I fix at my leisure because I don't have to be worried about the roof decking self destructing.
ANDYSZ2 WHY DO I HAVE TO EXPLAIN TO FRIENDS AND FAMILY THAT BEING A SOLE PROPRIETOR IS A REAL JOB?
REMODELER/PUNCHOUT SPECIALIST
Well here is always some application for the unconventional.
Mistake in your thinking -
Icy foam is not a VB. It will absorb moisture like a sponge and hang onto it. I am still trying to figure out why people use it. It will even do that from moisture in the air.
So when it is full of water it does not insulate.
That is why the heat.
But poorly done EPDM will ruin any house. That has little to do with the type of insulation
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FYI ... according to a website ... icynene will not absorb/take on water ... don't know how it stacks up as a vapor retarder (i.e. < 1.0 perm), but it says it inherently will not absorb water 'like a sponge'. Maybe someone else can fill in a gap or two here?
for the record, I have never used the icynene.But it IS open celled so it CAN take on and hold water.And dozens of people here on this forum have reported having seen problems due to just that very thing, mostly from condenstion in cathedral ceilings with less than enough R=value and humid interiors
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Time will tell, you are right but I agree with you.
A close friend sprayed his roof back around 1990. I had just started in the business and told him I did not like the idea of not allowing air to run along the underside of the roof.
What do i know?
Back in 01, he had to rip off the roof, rip off most of the plywood and re-roof. it had all rotted.
No indication of actual leak, so my assumption is just trapped moisture. Might have leaked but regardless, I rip homes apart all the time and find leaks that have been there for several years. As long as the area can dry, rarely do I see much rot or any real ugly stuff. (Vinyl siding, shingle roofs, ventilated attics) Put stucco on and the walls dont breathe near as much.
I once found mushrooms about 6" tall in the exterior stud bay. House did not let the leak dry and it was ugly!!
What kind of insulation?How applied?How much?What VB?Your observation means little without the context.
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Re. insulation on roof 20 years ago.
I dont know the details.
Wasnt it all impermiable back then?
Thickness, it was spec'd at R-30
Vapor barrier???
On ceiling None.
Under slab 6 mil poly. It was an auto garage.
We vented the vehicles when running so I am guessing we did not generate a lot of moisture but we never tested it.
Roof had 15 lb felt.
without the details, there is not enough info to support your conclusion.I will say that 15# felt makes for a pretty poor roof!
;)There has long been both open and closed cell foams.
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I have not reached any conclusions about the stuff. I have read articles where it was used very effectively and I am sure that in the right circumstances, the product works.
I can tell you that I am not so open minded to it at the present time because my limited experience with it was pretty negative.
Call me narrow minded, but the systems that I use work so I dont need to start fixing on them.
"I have not reached any conclusions about the stuff. "then maybe you could explain what you did mean when earlier you said that you agreed with him - the OP - that the insulation was the problem
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I was agreeing that I dont like the concept of the system
It requires exacting installation and if a tree branch falls on the roof and cuts the roofing membrane, even if installed properly, how long till the leak actually shows up somewhere where the homeowner will call for help. The water would be trapped between the roof membrane (whether rubber/shingles/steel/whatever) and the foam and might not be noticed for a long time.
I never get calls from clients asking me to complete an inspection of their existing roof and if not inspected, who would know it is leaking.
I believe it is a setup for a larger scale repair if something does go wrong.
Now, if it is installed in a steel and block structure and there is no wood or organic fibers in the system, I think it would be a very logical choice.
I am not saying I am right, I just would not do it.