I have a customer with a flat roof and they are trying to decide on a EPDM or a torch modified Bitumen roof system (both with tapered insulation) – their architect is pushing EPDM but my roofer insists the the torch applied is the way to go at a much lower cost. One of their priorities is using a environmentally friendly material and they think that the EPDM is the “greener” choice of the two – is that true?
There is currently an ancient, failing built up tar and gravel roof on a slab which we plan on overframing with a new wood deck for either new system to go over.
Thanks
Replies
"Greener" is hard to say. You really need to consider everything from production to disposal, and over the life of the roof. 60 mil EPDM should last at least 50 years, I doubt torch down will last that long. EPDM does involve solvents, but I don't know how that compares to the petroleum based products in torch down.
Personally, I always go with rubber, either EPDM or TroCal if you can find it. Longer life, no fire hazard installing, and easy to patch.
thanks! I appreciate the feedback
I'm mostly just bumping this back up to the top. But I do like EPDM. Was up on a mansard roof on tday (just looking at some fake slate that had been installed) and the epdm flat part was still in great shape (installed 15-20 years ago).
I have never used the Bitumen but would be surprised if it would hold up as long.
jt8
The creative individual has the capacity to free himself from the web of social pressures in which the rest of us are caught. He is capable of questioning the assumptions that the rest of us accept. -- John Gardner
Tell us about the fake slate please !!??
I forgot to take my camera with me otherwise I would have snapped some pics. It is the house I mentioned a while back. He yanked the real slate and smashed it up in the drive to make gravel out of it and then installed the fake slate. IIRC it was a Tamko product. Felt like stiff plastic. If I get back over there I will snap some new pics and try to dredge up that old thread. I believe he said he found some company in MO? that made the stamped tin ridge covering.
===end of hijack===jt8
The creative individual has the capacity to free himself from the web of social pressures in which the rest of us are caught. He is capable of questioning the assumptions that the rest of us accept. -- John Gardner
Thinking of changing your name to fakerslater?;)
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i have had both types installed on buildings.they are both good roofs,but there is a lot of difference.
if this roof is going to have any traffic to work on i would go with modified.it is really atough material.downside is it does have a seam evry 3 foot. does come in white so a little cooler than a black roof.have the roofer give you a sample and try and tear it.
i really like a epdm roof,there smooth,very few seams [25' sheets]. when there good there great. but let someone up there tromp around and punture the roof and it's really tough to find.i have had 1 that needed replaced at 15 years so thats nowhere near 50. but as far as i'm concerned if you get 20 years out of a flat roof it's some sort of miricale.larry
if a man speaks in the forest,and there's not a woman to hear him,is he still wrong?
I could probably type all night on this one if I wasn't so tired....
Short version is go with the EPDM .60 thickness. I'll probably flesh this out more in a while.
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I'll probably flesh this out more in a while
Rested up yet?
jt8
A year from now you may wish you had started today. -- Karen Lamb
OK, John wants to know more if you are still interested.
I started roofing in 1970 on BUR ( what you have now) roofs. They are skilled work to install, as are all flat roofs, and they all depend on the weather as well as the experience and integrity of the crew doing it for the final quality. It was possible to build a fifty year roof on a flat deck. More common was a fifteen year roof on a sloped deck that lasted 12 years...
Multiple plies of tarpaper bedded in hot tar was the basic method.
But about twenty years or so back, the industry started changing over to what are known as single ply membrane roofs. Instead of multiple plies, a single ply eliminated many of the seams which are the main source of leaks.
PVC, EPDM, and Mod-bit were the main contenders. The EPDM is a heavy rubber similar to what you hold when you have an inner tube from a tire in your hand. It can tolerate a lot of abuse by remaining flexible and had already been used in Europe for a long time. It commonly comes in 12' wide rolls and that fact accounts for few seams. There is still skill involved in seaming and flashing the walls and penetrations and edges, but it can be hard to make one leak, IMO.
The3 Mod-Bit takes a different approach, by essentially combining the elements of the old BUR in a single ply that is heated on the roof with a torch to adhere it to the base and to the previous roll at the lap. It requires few tools and less skill than any other roofing for flat/low-slope work. as a result, a lot of semi-skilled installers took it up and became competition for BUR roofers with more skills and more expensive equipment.
However, the weak spots are that the lap is only 4" wide and it can be poorly done. Heating the bitumen too hot or not enough creates a brittle seal or a barely watertight one. It can be harder to deal with some of the penetrations and walls also, so that is where I often find leaks caused by poor installs.
It is also a material more weakened by UV rays than is EPDM, so it must be coated every 5-10 years for long life.
I am prejudiced against the Mod-Bit for my own reasons, some of which do not apply to this discussion, but I truly believe that it is not a proper material for a full residence, and that a roofer trying to push it on a cost basis is unqualified to make any kind of recommendation as to which is best. The architect, in this case, has the better judgement.
As for the 'green' aspect, I think most of that is marketing 'hooey' on most products today, and can't really tell you with any certainty.
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