I am looking for advice. I have a 25′ x 75′ flat roof, on a building in San Francisco, that I need to replace. I intend to have the roof stripped down to the boards and replace it with a new system. traditionaly these roofs have been “tar and gravel” I have had several contractors suggest a multi layer membrane roof as well as others that swear by the tried and true “tar and gravel”. It doesn’t appear that cost is going to be the deciding factor. Any thoughts on which is the better way to go?
Thanks for your help
Steve
Replies
It doesn't appear that cost is going to be the deciding factor. Any thoughts on which is the better way to go?
Flat seam copper.
Like the Tucson, I shall rise again from the ashes.
don't fight mother nature- make it a sloped roof
TroCal, though I might be mis-spelling it. One of the key factors (in terms of longevity) for membrane roofs is thickness. TroCal is guarenteed for 50 years. EPDM (or is EBDM) is another, and it does come in varying thicknesses. Lab tests indicate that it looses about 1 ml a year.
" EPDM (or is EBDM) is another, and it does come in varying thicknesses. Lab tests indicate that it looses about 1 ml a year.""1 ml" Is this supposed to be 1 mil??This sounds bogus to me.My supplier lists EPDM in .045 and .06 thicknesses.So tests indicate that in 45 years the first sheet will no longer exist?Rich BeckmanAnother day, another tool.
I'm guessing that the references I've seen remove the decimal. 60 is what we use in box gutters and roofs, which I imagine corresponds to 0.06. Kinda like milege rates on property taxes or something. Me, I wish everyone did it your way, with the actual measurement. Makes my head hurt trying to remember what's what. 60 should last 50 years, with all the usual caveats about proper installation, not wearing your golf spikes to keep from sliding off the roof, etc.
Not familiar with Tro cal
,but the rubber is EPDM
Ethyl
Propelyne
Diene
Monimeris how my memory records itI also doubt that it loses that much. I can well imagine that itmight lose one in the first yreaar due to shrinkage stabilization or affgsing, but it would tend to be a reducing scale fom there.The EPDMs had a foty year success histroy in Europe before being introduced into this country.
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Foam and elastomeric coating or polyurea coating. Generally a 50 mil coating that loses about a mil a year. Can be recoated without extra work (no reconstruction...just clean and recoat).
The newer membrane roofing products are all single ply, so I'm confused as to what they might be recommending in lieu of a BUR gravel roof.
For my money, an EPDM rubber is the way to go here.
Cloud, that foam may work fine on a dome where it is sloping and draining well, and it would combine well with your system but I would never recommend it for a flat roof. Far too many failures and i have never seen or heard of a Professional Roofer ( as opposed to someone who has bought into a foam franchise and otherwise unskilled in basic roofing skills.) who would put his name behind such a recommendation
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I'll let a contractor come and defend their own business if they wanna...not my battle. I don't deal with flat roofs...just giving the guy something else to look at that other people have used for the same application. Companies I've talked to claim they have tens of millions of sf of roofs under warranty. Are they all wrong? I dunno. To discount them as being unqualified be/c that's their business...seems a broad brush.
Edited 2/24/2005 2:23 pm ET by Cloud Hidden
The newer membrane roofing products are all single ply, so I'm confused as to what they might be recommending in lieu of a BUR gravel roof.
Piffin
My uncle was a former VP for GAF and he cleared up the notion for me that all new membrane products are single ply. We here in the east get bombarded with single ply rubber because Carlisle is here in PA. Out in Southern California, rubber represents a small part of the total roof business. Built up is still the biggest seller, by far. And for good reason in my opinion. I think both are great products. In my 20 years, I have only seen built up used a couple of times on my own jobs. Rubber on the other hand, geez, it's all we seem to do.
The reason I think so highly of the built up roofs is that I have been on so many 45 year old built ups that are just now needing replacement.
Unfortunately, I can't say the same for rubber. I see seam failures, edge failures, cooking grease causing degradation, holes from foot traffic, etc. Granted the rubber hasn't been here as long, but it is definitely a more fragile product.
If I lived in San Francisco, I wouldn't think twice about it. It would be a built up for me. I'm sure that you would find that 80% of the flat roof guys out there specialize in it and are experts at it. Here in PA, the reverse would be true. Here, I would probably use rubber or TPO.
As far as the foam with the coating....... as soon as we get one contractor doing it to hang around long enough to warrant it past a couple of years, maybe I'll consider it. Till then, no way.
Tried and true.
carpenter in transition
We are in agreement. The new systems are single ply and the old BUR is multi-ply. It was the original statement that cinfused me. he mentioned NEW multi-plu roofing systems. The only "new" multi ply that I am aware of is actually between twenty and thirty years old and is a polyester woven sheet with cold applied emulsion and that is of questionable quality, and limited ideal application.I have nothing against either system between EPDM or BUR - when it is installed properly. When I was a roofer, I had the kettle and did miles of moppiong and rolling. Since then I ususally call for EPDM and have subs do it. it is more forgiving and easier to repair, not that I have needed any repair work yet with it. I took the install schooling for it just before I got out of roofing and into remo work, so I have never done an install myself, but have overseen plenty.but as you point out with flaws in the rubber roofs, the quality of the final product depends greatly on the quality of the instalation. I have seen more than my share of idiotic work on BUR too. Things like over-heated asphalt, damp paper or base sheet, skipping proper steps in rtying in flashings, plain old losers doing the job, etc. can all lead to early failure of the BUR systems. The reputation and experience of the installer is the primary ingredient in the success of the roof, especially with a flat roof.
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Cloud,
untill somebody proves to me differently, My recommendation against the urethene roofing will stand.Here is what I base me opinion on :Every time I bid on a roof that generally was a low pitched BUR, I would fiond myself in competition with a foam guy who had just gotten into the business within the previous two years. His selling points would be that the old roof did not need to be removed, saving labour and disposall fees, and that his system would also add insulation to the roof and save energy. I actually thought of inveting in the idea and doing the same installations.But after a couple years, I noticed that almost every single one of these roofs developed leaks. The owners seemed to call me for their leak repair. Interesting, no? The installers were always long gone and /or unwilling to deal with the troubles they had created. I coule type for an hour naming all those specifics, but the short version is that they did not have a bsic understanding of water, or of any material other than their own, or of basic roofing pribnciples. They totally depended on the adhesive qualities of the product to overcome all their ignorance and when faced with that failure, they ran and hid in shamme. The system is not unlike putting a mansteer sixed tube of caulking in the hands of the fifty foot woman and letting her smoather the goop all over the rooftiop, and hoping that it would stopp all leaks.Then there is the fact that UV degrtades the foam. The coating is supposed to protect against that, but again, it is a thin liquid membrane, so the quality of that protective skin is totally dependent on the applicator's skills and the weather at the time of application.On a new dome, I can imagine a good man getting a good job, but when semiskilled people use this material on older flat roofs with old existing flashings, it is little more than a patch job.
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Your description of a foam based roof and mine don't match. The ones described to me involve starting with a proper substrate, adding foam properly for insulation, paying attention to details of flashing pipes, ac units, creating proper edges, etc., and then coating with, as one example, 50 mil of polyurea. You ever see 50 mil polyurea? That's some tough stuff. Will completely block UV. Up to 700% elongation. Won't rip. Hail resistant. Used on water tanks and all sorts of stuff.Our evening news is full of stories of schools with _traditional_ roof systems that have failed and become sources of mold. Tens of thousands, or maybe hundreds of thousands, of roofs. Millions of dollars. Schools closed and teachers and kids sick. Is it a failure of the system or the materials or the installation or the maintenance? Not my business to figure out.I'll just urge care before ripping the whole industry. We must be encountering different parts of it. What you describe sounds like hacks. The people I've spoken with have been working this field literally for decades. And the industry cares about quality, too. Here's just one program for trying to institute quality standards:"The Performance Based Studies Research Group (PBSRG, http://www.pbsrg.com) was developed by Dr. Dean Kashiwagi at Arizona State University's Del E. Webb School of Construction in 1994. The PBSRG, a non-profit research group, developed the ALPHA Research Project to analyze performance information and identify high performance roofing systems, specialty contractors and facility systems in the construction industry.For the purposes of the ALPHA project, an "ALPHA Roof System" is defined as any low slope roofing system with a documented performance that meets or exceeds that of a conventional, 20-year-life-expectancy, low-slope, built-up roofing (BUR) assembly.The program is open to all roofing systems. Any manufacturer, product or group of contractors that can demonstrate - when randomly sampled by PBSRG every other year - that 98% of their customers are satisfied with their roofs, 98% of their roofs don't leak and they are willing to have all newly installed roofs over 5,000ft2 surveyed yearly qualifies for inclusion in the program.Since its inception in 1996, only one system has qualified for ALPHA: Spray Polyurethane Foam.There are 10 ALPHA contractors across the United States. To date:484 roofs have been inspected
341 customer responses have been received
the oldest installation is 30 years old
the average installation is 10 years old
99% of the jobs are completed on time
99% of the roofs do not leak
99% of the customers are satisfied
the average contractor performance rating is 9.7 out of 10
The ALPHA system offers a 15-year warranty with almost no exclusions."
OK, I'm taking a look at that site and the linking BASF site. We'll see what I can learn.But with only ten contractors in the country, it is understandable that I wouldn't have heard of this paerticular type of polyurethyne roofing before, and I still wonder, if it is all that good, why are there only ten in all this time doing it?
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It's only ten who have gone through that certification, not who apply the materials properly. The guy I know best who's considered it is following the practices and using the same materials, but didn't (iirc) meet their rules for sf of roofs in last year or five years, be/c he's done other things, too (his dome work didn't count toward the total, for example). And there's a big cost for the surveys and inspections of roofs that only some contractors can afford.The point, of course, is that it's an application that does have standards and a good track record if one looks in the right places. There are people who do it well and do a lot of it. Those who don't do it well, like those who frame badly, paint badly, design badly...are showing their lack of skill rather than a flaw inherent in the materials or methods.I don't know if the building that started this thread is a candidate for this method or not. Maybe it doesn't need insulation. Who knows. But it's a possibility he can explore.
> There are 10 ALPHA contractors across the United States
Any in Los Angeles?
-- J.S.
As additional clarification; this building has had a Tar and Gravel roof since it was built in 1913. Best that I can tell is that this is the 3rd one in 92 years. The roof system being suggested by several contractors is a two ply system consisting of one ply of Certain Teed Fllintlastic SA Base mechanically fastened and one ply of Flintlastic SA Cap (self adhering SBS) Modified Bitumen Membrane. Curbs, Skylights etc. would have an additional layer of the Flintlastic SA Mid Ply membrane. The cost differential between this system and a traditional T & G roof is not great enough to drive the decision. I am looking for the best most trouble free solution. This roof does not get foot trafic, snow or wind blown debris.
Any thoughts on how I should go?
Steve
That sounds like a torch down application, many of which are only ten year products, and you need to be sure to check the insurance they carry if they are using a torch to apply it on your house. I am not a fan of the torch down modified bitumens.They do definitely require a minimal slope. I think you said that yours was flat. Dead level flat? or terminology only?
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Piff,
one ply of Flintlastic SA Cap (self adhering SBS)
The product he is talking about is a cold applied Modified:
http://www.certainteed.com/NR/rdonlyres/DCD99073-AE89-438C-AB93-A61B684C09A4/0/flintlasticsa.pdf
Our roofer installs this, with success. I have not used it on one of my jobs and would have to consult with them on advantages/disadvantages vs. a built-up.
carpenter in transition
I can't think of a cold applied bitumen I would trust on a flat roof, unless tremendous advances ahve taken place in the last decade or so, but I understand why. Densely populated areas make lioabilities for hot applied intolerable and some local authorities have encated laws against the VOCs produced.
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Flintasitc I have used....comes with a granule surface colors vary goes down fast and easy nail base sheet down to good wood peel n stick mid and top ply. Here around DC you gotta have the 3ply system for an habitable space....shed ok for 2ply.
I skipped past epdm....and went from torch to peal n stick.
my insurance co don't wanna hear I'm doing torchdowns.....ok for me nomore goooop on my boot.
I still have my kettle... and the last built up i did was on my building... well heck all my jobs have been my buildings... but anyway... i did 5 plys 16" cants on the parapit walls... did torch down on the parapit and vented it... plus have at least 40 roof vents on 12,000 sf it all drains to one end and 4 12"sq scuppers... i installed it on a stripped deck (27 dumptruck loads came off) and i put 4" of rigid foam on the deck...
all that said... since then (and my draggon wagon) all i do is torch down... i feel i get as good as if i did a 5 ply hot mop... materials cost less... and on a clear roof i can put down a square in less than 20 min... ( i have done 5sq in an hour)... and unlike rubber ... u can play basketball on this stuff and not do damage... i also have a problem with how well a rubber roof seals a building... i just don't see the vents in rubber you do in bu or torch down... and not sure i'd want to be seal'n around the vents in rubber either... but lay rubber on any surface and you will have moisture under it the next morning...
just my 2 cents
pony
Okay, I'll jump in with my flat roof question. I've been looking at several houses torch down roofed about 7-10 yrs ago by the same person. The roofs are failing. Cracking where the material turns up at the eave (Dutch Gutter), and blistering in places along the seams. They were done by an experienced roofer who is no longer in business for health reasons. As far as I can tell his application was ok. I had thought to expect a longer life from this material, like 15 -20 yrs maybe? What is typical?
I guess I have a little bit of a peeve in this regard.You see, All my life, I have listened to people make statemnets like " Anybody who would design a flat roof on a house in this climate ( no matter where they were ) oughta be shot! It is impossible to keep a flat roof from leaking!"But the fact of the matter is that flat roofs are a very practical design in many cases, and the main reasoin for leaks in flat roofs is human failure. Either hacks did the original installation or owners failed to do appropriate maintainace, or hacks doing other work on the building managed to ruin the roofs surface. get a good man to install, and then listen to how to maintain, and keep the painters, electricians, etc from sdestroying it and the roof will last from fifteen to forty years with no troubles.
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I agree.I'm not a roofer but I have been up on a few of them. I have seen simple but well installed tar and gravel roofs that were 60 years old and still going strong with only minimum maintenance. Mostly keeping the leaves and branches off them, keeping the scuppers or drains clear and keeping trades from knocking holes in them or damaging the flashing with ladders.And this is Florida where the sun eats roofing materials, the rain comes down hard and summer storms and hurricanes beat on everything. It seems to be all about the quality of the installation.Seen super-dupper membranes give up in a few months next door to a building with tar and gravel flat roof that was still kicking in its fourth decade.
Thanks for this post in support of low slope roofs.
As we have seen from at least one of your past posts, when a client purchases a beautiful lake front lot, it is almost second nature that the new home is going to have a second floor deck more than likely with living space below. Are we to tell the client that they can't have this because we don't like low slope roofs ?
I tend to encourage people to consider outdoor spaces like this to take advantage of the great outdoors. I also encourage them to get the best installer to put the best product on the roof.
Can you imagine telling Frank Lloyd Wright or Philip Johnson " No flat roofs ! "
Low slope roofs have their place and as I have said before, when properly installed and maintained, can last at least 45 years. I doubt the latest "45 Year" fiberglass shingles will last that long.
carpenter in transition
Re-reading a bit tell your uncle that GAF was generally at the top of my recommend list.
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While you're at it, put in huge freaking scuppers. Go up there and clean them annually before the rainy season. Every year we see TV news stories about the $50k - $250k flat roof collapse that could have been prevented by just getting the crud out.
-- J.S.