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mgfuns 07-04-2010 08:02 PM

Flat roof resurface--EPDM, Torch Down, Cold Applied bitumen
Hey all,

New to the forum. I used the search function a little bit and couldn't find any clear answers. So sorry if this is a repeat to something you see a lot of.

We have a 60' x 15' low pitch flat roof over an addition. It was last resheated, reinsulated, and covered with a cold applied bitument roofing. The guy double layered it and it lasted 20 years. Now all the aggregate is coming out and there are a few small leaks. Time to get it replaced.

We've begun to get estimates...4 so far. Normally I would try to do something like this myself but its too big and I've been too busy. Apparently getting insurance coverage for residential torch down is very difficult so very few installers do it.

Can anyone speak to EPDM vs Torch Down vs cold applied? I have had someone say the EPDM is way better htan torch down, someone say cold applied with last 40 years, and someone else say that the EPDM is very thin and squirells could even puncture it and I should just do torch down.

To give you an idea of the estimates I've gotten, they're all pretty similar (hgiher than I'd like but similar), so I'm more interested in what will be a quality product.

Torch down over existing- $5K
Strip off current and put 60mil EPDM over fiberboard- 6K
Strip off old and install cold applied bitument- 5K

Let me know what you think. This looks like a great forum! Thanks!

Grumpy 07-06-2010 09:15 AM

This is something we roofers discuss often. Everyone has a favorite, but at the end of the day modified bitumen and EPDM are both very good roofs that when properly installed can and will last 20 years. Infact EPDM can be warranted up to 30 years on commercial properties.

Forget that for a minute, because while the material is important, the specification is more important. What I mean is modified bitumen has a 10 year, 12 year, 15 year and 20 year specification. EPDM has a 10 year, 15 year 20 year and 30 year specification. At different "year ratings" the thickness of the material and the way that material is installed changes. for example a 10 year modified bitument roof is a base sheet with a smooth black modified bitumen. A 20 year modified bitumen is a double layer of base sheet, a smooth modified bitumen mid ply and a granulated modified bitumen cap sheet. More labor and more material means a roof that lasts twice as long. A 10 year EPDM might be a 45 mil mechanically attached while a 30 year EPDM is a 90 mil fully adhered and double seamed. Who in their right mind would install a 10 year roof? It's just ridiculious!

My advice stay away from who ever said the cold process will last 40 years. Yeah the roof could last 40 years but in theory would require so much repair after 20 years it wouldn't be worth nursing. The only roofs I have ever seen last 40 years would be coal tar pitch. Very Very uncommon anymore for insurance reasons and price.

Squirrels will dig through modified bitumen just as easy as EPDM. I have never seen a squirrel dig through either membrane at a random location in the field of the roof, most commonly they would chew through flashings or existing cracks and just make those cracks bigger. Furthermore in an unscientific test I encourage you tog et a piece of 90 mill EPDM and a piece of modified bitumen. Just take your keys and use equal pressure to smack the two materials. Look at the impression your keys leaves behind. The key will sink almost completely through the modified bitumen but will barely scratch the EPDM.

For $5k on a lay over, FAIL IMO. You always get a better roof with a tear off, depending on how they plan to lay over (install a recovery/fiber board or just go over the existing) would dictate price.

I see nothing out of line with the EPDM nor the cold applied bitumen price assuming both are 20 year specifications. There is ALOT of gray area in what is being done.

My favorite? I personally prefer single ply. We still install modified bitumen on request but for the fire/safety reasons primarily prefer the single ply. Single ply is EPDM, TPO and PVC. I personally prefer the heat wleded seams you get with TPO or PVC. An EPDM roof, like any roof, will fail first from it's seams and penetrations. EPDM the membrane will last forever, the seams will fail at some point in time which is why you will note I mentioned above double seaming in the 30 year spec. But like i said I prefer the heat welding of the seams using forced hot air, no flame, of a TPO or PVC roof. Also TPO and PVC are reflective and "cool roofs" are becoming more and more popular, infact have become code in the Chicago area as of 2009.

That's not to say you should go out and seek a TPO or PVC bid. Any of the roofs you mentioned will last 20 years if installed properly. I recommend reading this, which will help you in selecting a contractor. At the end of the day it should come down to who ever you trust the most. Who took the most time to identify your needs, and explain your options. Who seems like they really cared about your project. Who has the best reputation within the community. Those things matter as much, if not more, than the type of roof to be installed.

mgfuns 07-06-2010 07:20 PM


Thanks a lot for your thorough response. I appreciate you taking the time out to respond. I'm in the metro nyc area--if I were in Chicago I'd give you a ring for sure.

Is it reasonable for me to request white EPDM? I don't really like the look of the silver stuff and the white would definitely save me some heating costs. Should I anticipate a price increase.

Do you think the torch down over the existing is a "FAIL" because of its price or because torch down over an existing crumbling surface is not a good idea. I got a quote for a complete strip off and new layer of torch down and that was 8K...which seemed TOTALLY ridiculous to me.

Grumpy 07-07-2010 12:10 PM

White does cost a bit more than the charcoal/grey/black epdm. The cool white roof issue is controversial but I support it. Some say the heat gain in the summer time is not as important than the heat gain in the winter time. I say if youa re depending on your roof to heat your living space, you've got problems. There is no doubt it does play a part, but with proper insulation that heat gain is minimalized.

Definetly do NOT silvercoat an epdm roof with the traditional off the shelf silver coat products used for asphalt roofing. You will likely be instantly voiding your epdm warranty and damaging the membrane beyond repair.

I said fail for both reasons you mentioned... but I don't know their scope of work. If they were to be installing a recovery board, base sheet(s) and new cap sheet then I don't see the price being an issue. What most guys around here would do is simply torch over the existing, while I have done this, it creates a 10 year roof. If that's your anticipation and desire then go for it, but for that then yes it may be alot of $$. However I would not personally torch over a crumbling cracked surface that might allow flame into the overall roof assembly and substrate. In other words I do not know how badly it is cracked.

You've gotta tell me more about the scope of work and specification for me to tell you what pricing may or may not be ridiculious. Is insulation involved? If so what kind and how thick? I've done some jobs where the insulation has literally doubled the cost of the job if the roof would have been done without insulation. Also I am not familair with new york codes if insulation of the roof is a requirement or not.

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