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I’m a builder in the Sierra foothills of California. In the summer the temperature runs in the 90’s to 100’s. In the winter it will be in the 40’s to 50’s with an average rainfall of 40 inches. What type of roofing will last the longest on a flat roof in this enviornment?
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A standing seam metal roof w/ a 1/4 per 12 slope.
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Steve,
Here in NE Ohio, my flat roof material of choice is EPDM(rubber) membrane. I usually use RPI brand or Internationl. Suppliers around here only stock black membrane, but I'm sure in your area with a much longer warm season white would be in stock. I use 20'x 100' rolls whenever I can to keep seams to a minimum.
The materials are available here to anyone, but if you want to offer a warranted system you must be certified by the mfr. Some companies market their product directly to building owners, but I don't recommend any flat roof system to novices. The investment and the stakes are too high.
Hope this helps, John
*40" of annual rainfall and a flat roof. Designer of the year. Only in America. God I love this board.JonC
*Steve, is your roof "dead level" flat? Or does it have some slope built in so water doesn't pond? Is it new construction or a reroof? Is it commercial or residential?I only ask because of JonC's comments. Dead level roofs are one of the worst ideas an architect has ever come up with-mainly because they stay dead level about as long as it takes the ink to dry on the first bank draw. They invariably sag with time and the drains are always located near a column or beam, meaning that the drain is now in a high spot They are against code on new construction in many areas.I don't like them(flat roofs) on residential buildings simply because I prefer the look of a gable roof(never much cared for the long flat contemparary look).And it goes against the "form follows function" school of thought. Incidentally, the flat roofs on Frank Lloyd Wright's Falling Water home did severe damage to the structure and cost a small fortune to repair.Now, when it comes to commercial/industrial buildings, the cold hard econmic fact is that flat roofs will always be with us. Problems arise when builders/architects/developers try to cut corners and not provide enough slope, or enough drains, so that the water runs off quickly. Most codes address this. I have a lot of jobs out there roofed with EPDM(I put my first one on in 1983 and it's still going strong) so I know that good materials and good installation combine to make a good, minimally serviced roof. I will admit, some buildings are hopeless, and I have trussed and shingled over many a flat roof. It is still my favorite kind of roof job, but there are few building owners willing to invest that kind of money in their roof.John
*Well I guess I'd have to vote against any kind of metal roofing on a flat roof. I don't recall ever seeing a manufacturer's instruction sheet that allowed less than a 3 in 12 pitch. Less than that and puddling, corrosion and leaks are almost inevitable.Most of the non-leaking flat roofs I know of use some type of membrane.
*JRS,Is there any chance we are related?We come from the same area and your take on flat roofs and,particularly, the ineptness of some of Frank Loyd Wright's designs sounds un-cannily familiar to me.Where are you finding 20x100 rolls? I can only locate 20x50 or 10x100.Would love to have white epdm available here.Several times have had customers sold on epdm untill they found that black was their only choice.(although in my opinion anyone who turns down a superior product because of COLOR for a roof surface that can not be seen from the ground and can only be seen from rooftop or 1 small awkwardly placed bathroom window,deserves to keep their old leaking roof)Good Luck,Stephen
*Hi Guys,Very hot weather, lots of rain, flat roof.This would require a membrane roof such as hot mop or bitutene for the flat part.This would require a parapet around the perimeter with scuppers to drain the water.This would require insulation board on top with ballast (available in any colour) to protect the membrane from the heat.Almost sounds like a standard inverted roof doesn't it?Standing seam metal roofing on a flat roof, not very bright.Gabe
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Torch-down.....not the roofing, the whole building...build a gable....
-BCC
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Oh, Jon C, you made me laugh today. Thank you.
Steve, with a flat roof, my vote would be:
1. Hot Mop. Cheap, easy, smelly, won't last more than 10 years.
2. EPDM. Expensive, hard to install. You should get 20 years out of it.
I guess the choice depends on the homeowner huh?
*We're just brother roofers I guess. You should be able to get 20x100 rolls from Modern Builders Supply. I take it you work in Cleveland? I live in Wadsworth, and do most of my work in Summit,Medina,Portage,& Stark counties.I have ventured up to Cleve. for a few jobs.Hey, I agreed with your comments on T-lock shingles on the other thread so completely, I didn't bother adding anything to them. Maybe we could get together for lunch sometime and find something that we disagree about?John
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With tongue only slightly in cheek, why not sod? Membrane first, drainage layer, dirt, sod. The grass will reduce rain runoff, increase cooling efficiency, reduce smog, etc.
*Hey Lisa - Your right on with the sod roof suggestion. I've seen several of these and they are elegant with a solid dash of eco-friendly thrown in. Best, docseven
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Weight becomes a significant factor.
*So Does Lawn MowingStephen
*Steve: I agree with the first post. If you can get 1/4: 12 pitch use a standing seam metal roof. We put our first standing seam roof down in May of 1974. The roof pitch is 1/4:12. The roof is still in excellent shape with many years of usefull life to go. It has been thru numerous hail storms several of which were very severe. The buildings around it were re-roofed but the metal came thru the hail with no damage. We use the standing seam roof on many of our commerical buildings. We install them on wood or steel const. They are not cheap to do. The initial cost is more than any other roof but the life cycle cost is much less. In the long run the most economical way to go by far. Do not confuse a standing seam roof with a screwed down roof. No comparsion. Our temperature extreme here is +110 in summer to -35 below in winter. One word of caution, not all standing seam roof are equal. There are some out there that are junk. If you consider one of these do your homework.Ron.
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Hey JRS,
When it comes to flat roofs, I know "next to nothing" about them. Problem is, My sister's house up in Michigan has one and its leaking bad!
From what I've gathered, most of her troubles stem from skylights not properly flashed, and I think there are tears in the fabric where the kneel walls (parapet walls?) meet the roof deck. Evidently no cant strips to ease the 90 degree transition from wall to roof. Anyway, she was hoping I could come up there and put down a new roof. I've never done a torch down job and told her sorry, can't do. Well, a buddie of mine at work gave me some info on a new, adhesive backed, EPDM roofing material that does not require torching of the seams.
This product is called KWIK PLY and is manufactured by Hyload Roofing Systems, Wadsworth, Ohio. Ever heard of them? Is this system any good? The rolls come in 3'X 36' and the epdm thickness is 50 mils.
They claim you first tack down a base sheet material, overtop of regular 15# felt onto the deck. Then, you are to prime this material with a quick dry primer that conforms to ASTM D41. They say to wait a day, to make sure primer is dry, and then to go ahead and install the final, 50 mil epdm sheet overtop. this stuff is adhesive backed, is rolled out, paper wrapping removed, and then rolled down with a 70 # lineoleum roller.
They say top laps should be 3" and end laps to be 9". They require additional membrane lapping for flashing areas, standpipes, etc. They say to end the membrane on the knee walls by installing a metal pressure bar onto the wall and sealing the top edge with a urethane caulk. All end lap joints and flashing joints require this caulk. The normal top overlaps do not.
This membrane goes by the trade name, "ELVALOY" and is made by Dupont.
Have you any experience with this type of system? If so, will it work, or would I be wasting my time? The material price on this stuff works out to about 85 cents per square foot; or so I'm told.
Any feedback you can give me would be appreciated.
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Hi davo,
When you talk about "EPDM" and "torching seams" you are actually talking about two totally different systems. EPDM(which is truly a synthetic rubber)is seamed with chemical adhesives, much like the inner tube patch you may have used on your bicycle when you were a kid.
Torch down roofing is actually a chemically modified asphalt(or bitumen-pronounced bitch-oo-men) that has no synthetic rubber in it at all. I have seen more than one owner insist they have a rubber roof, when in fact they have a modified asphalt roof.
The confusion, in my opinion, comes from two sources. One, GAF has a torch down product called Ruberoid(pronounced roo-ber-oid). Notice it is spelled with one R only. It is named after a man named Ruber who helped develope it. It does not stand for rubber. Two, the material is made by somehow polymerizing asphalt to make it extremely flexible in a wide temperature band. Sales reps would say the asphalt is "rubberized". Therefore, the mistaken connection to a rubber(EPDM) roof. I happen to believe this confusion is encouraged by the modified proponents.
Davo, I think you are wise in not wanting to take a torch to your sister's roof.Though I rarely install them now, I have put on a number of torch down roofs and never had a problem, but I can tell you, there have been a number of high profile fires that were started by a roofer's torch. I rest easier not having to worry about the chance of fire on one of my jobs.
Now, after all that background, to your question. The product you describe is practically made in my back yard. I have never installed that particular brand, but generically, it can be a good system, IF there is no ponding water on the roof, IF you have a good, smooth, surface to go over, IF you have good drainage, IF you have good, warm, dry, weather to work, IF you follow the mfrs. directions to a tee(good advice for any product).
I'll be happy to give you advice, but the best advice I can give is that flat roofs are best left to professionals with plenty of experience.
Good luck, and keep asking away, John
*JRS,Thanks for the info John. I have experience with roofs; but mainly hips, gables, and sheds. I've worked only a few times on flat roofs, and in each case, I was installing strusses and converting the flat to a gable; which is really what I would rather be doing with my sister's house, but the cost of doing this is more than she wants to spend. This Kwik Ply method might still be the way to go.Thanks again,Davo
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I’m a builder in the Sierra foothills of California. In the summer the temperature runs in the 90’s to 100’s. In the winter it will be in the 40’s to 50’s with an average rainfall of 40 inches. What type of roofing will last the longest on a flat roof in this enviornment?