OK, so since The Oracle has forbade me from learning flat roofing OTJ, I passed on helping out my friend with his store’s new roof. S
Subsequently, he asked me for my opinions on the bids he got. We narrowed it down to two of the four, they are quite close in cost and sem to cover the same approximate scope, but one is using EPDM and the other is a modified torch down. I know essentially what each of those means, but that’s about it. Anyone feel like giving me a Reader’s Digest sense of the practical differences, pros and cons?
Thanks as always…
PaulB
Edited 3/17/2005 4:46 pm ET by PaulB
Replies
I have a strong prejudice towards the EPDM rubber roofing and away from the torn down.
Fiorst, in terms of maintainance - theEPDM is a forty year roof if applied properly. Other than cleaningm it needs no maint. The torch down is a ten year roof unless you apply a coating every five to ten years, depending.
in principle they are different too.
The primary cause of leaks in any flat or low slope roof is the seams. one obvious solution to that is to reduce or eliminate the number os seams. With EPDM, at 12' wide rools, there are at least a fourth as many seams as in a roll roofing product.
With torch down modified bitumen, you are using a torch to heat the product in place. This is fine on larger open projects such as I imagine you are studying. But on many buildings, the torch is a great liability. Buildings have bneen burned by them. And more than the insurance industry will ecver know about have had small fires due to the presence of the torches on the roofs.
The process of torch down is also suspect, in my mind. The bitumen has to be heated to just the right temp for an optimal adhereance and edge seal. That takes skill. And good weather. Too hot and it cruystalizes and you have a weak roof with brittle seals at laps. Too cool, and you hav no seal at all.
My main prejudice against the modifieds comes from my background in BUR and hot asphalt that it was intended to replace. There is no modified on the market that can compare to a properly installed BUR roofing. It is simply a cheap substitute.
I do not do roofing any more, for several years, but I believe that i could do a modified for much less money than I could do a good EPDM roof, details notwithstanding.
So, Having not seen your job, IMOP, the EPDM for the same money is the better job package.
But with any roof suystem, the experience and skill of the installers is the primary factor.
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Taunton University of Knowledge FHB Campus at Breaktime.
where ...
Excellence is its own reward!
A great help Oh Oracle... thank you as always! I'll pass your comments on to my buddy.
PaulB
Hi Paul,
I went to some seminars on using the Mulehide EPDM system a while back
and have done about 6 roofs now, mostly on additions I have built. You might want to see if they are doing seminars in your area. There are also videos available.
I'm not a roofer but wanted to use EPDM on a building I own and am renovating. I think tar is an antiquated method and that torch down is
a midway point between tar and EPDM. The torch down stuff is modified bitumen not EPDM.
Bottom line is it doesn't matter if you use Mulehide or another EPDM roofing product but it is the way to go for flat roofs. The only that
may be better is PVC. But that is used for roof decks that take rough treatment. It is tougher but more expensive.
Good luck!
Tom
Thanks for the suggestion Iron. I take lots of seminars, and this one sounds interesting but I decided (on the strong suggestion of "The Oracle of Maine") to pass on this job. My buddy's having a local roofer with lots of EPDM experience handle this...
If the roofer doesn't mind maybe he'd let you hang out and help with
grunt work in exchange for watching the process?Tom
Good idea. That's how I've learned most of what I know. You're almost as paranoid as the people that're trying to kill me.
Great idea, I think I'll run it by him. Least he can do for the referral ;)
PaulB
without knowing everything involved, the decision is not always cut and dry.
i too, like EPDM, but i have a peeve about it being installed over existing roofs. i strongly feel that all existing membranes should be removed. these old membranes tend to hold and store water that later comes back to haunt the new EPDM.
carpenter in transition
From the (very) very little I know about it I'd agree Tim. This is gonna be a tear off job...
That is true for ANY roof system so it shouldn't qualify as a criticism of EPDM
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
thanks, i agree.
for some reason, i seem to see more problems with EPDM (usually rubber) seam failures over old built-up roofs than problems with modified bitumen over old built-ups.
just another quick point here, when i said that i felt that the decision to use EPDM isn't always cut and dry, i felt the need to clarify. living in the northeast, we have many very old structures here with existing built-up roof systems which often tie into adjoining properties owned by others. in situations such as this, i am not always sold on using EPDM as a replacement for a built-up that will require a tie-in to another existing built-up.
i think they call the decision 'situationally dependent.'
carpenter in transition
Tim,you are absolutely right about going right over an old roof.
Always good to tear down to the sheathing then nail fiberboard or an iso-foamboard that is compatible and glue to that.Of course we haven't touched on the different attachment methods for EPDM but seems the most common is a fully adhered adhesive method using either solvent or water based adhesive.Tom
tom
yes, fully adhered for residential is by far the most popular method. as far as using fibreboard (recovery board), we are trying to shy away from this product in situations where any foot traffic will happen on the roof. we have seen many instances where the recovery board is crushing and breaking apart under the rubber. screwing 1/2" (min) plywood instead has proved to be a good solution. screwing is the key, nailing is not permitted due to nails backing into the rubber.
carpenter in transition
Tim,For anyplace there might be occasional foot traffic I will put down
this yellow spaghetti like stuff that comes in rolls.
Usually it is from a window or door to an AC unit on the roof that needs
maintainance.Anytime there is regular use PVC is the way to go.Tom
I just had installed 800 sf of torchdown. It cost me $3/sf for labor plus materials (don't have that tally at the moment). They seemed to do a thorough job, with a substantial LCC drip edge, though there are a couple of spots where it isnt' fully adhered to the deck. I added tapered 2x4's on top of all the joists to minimize any ponding. The one detail I wasn't happy with is that they torched the roofing up the sidewall, which has made siding difficult, and I suppose reroofing in the future difficult. I would have preferred LCC flashing at the side walls.
Paul, several things to consider.
Both systems will give you a long term roof.
How do they intend to install the EPDM? fully adhered, mechanically fastened or ballasted.
What types and thicknesses of insulation are they installing. This will impact on the overall cost.
The EPDM membrane will last a long time.... however, we have repaired many 10-15 yr. old roofs due to the detail materials breaking down etc. ..... all installed to then current standards.
2 Ply Modified Bitumen with a granulated top surface will not require re-coating after 10 years. However, it should not be used on dead flat roofs, min. 2% slope is ideal. If the building is wood structure, torch on, although can be done, is very risky. You should also check for proper insurance for torching. We have to carry liabilty ins. that covers hot work, both for torch and for BUR.