Need help deciding between EPDM and APP flat roof

Hello everyone,

I’m a new homeowner and know nothing about roofing or how to deal with contractors really. When we bought this house a year ago we knew that the flat roof was going to need replacing very soon and here we are (thanks Hurricane Sandy - we sprang a leak).

I have two estimates, both of which are recommending different things but for roughly the same price. I am hoping to get from the community here three things:
A) what questions do I need to be asking about these estimates
B) is there anything missing from them
C) which roofing surface is better and why?
I live in the Washington, D.C. area (close-in suburban Maryland). So we have pretty hot (95-100 deg) but not Florida summers and pretty cold (5-30 deg) but not New England winters. This flat roof is on the west side (back yard) of our property and is over a one-story addition in the back of the house that’s roughly 600 sf. The house itself is old (1917) but I don’t know when this addition was put on; our inspector said it was likely put on soon after the house was built but I don’t really know. The roofer that gave me the second estimate said there were 2 and maybe 3 roofs underneath the current one that need tearing off.

Estimate one:

  • Remove existing flat roof down to decking
  • Inspect and replace rotted plywood decking at a charge of $65/sheet installed
  • Install 1/2" fiberboard insulation using required screws and plates
  • Install new 032 aluminum drip edge and slag-stop on edges
  • Install Firestone 060 mil EPDM membrane fully adhered
  • Clean up and remove all job-related debris
  • Cost: $3,860
  • One-year workmanship warranty, price-match for “qualified contractors”

Estimate two:

  • Remove existing flat roof down to decking
  • Any rotten wood replacement is an extra charge of $4/linear foot or $3/square foot for plywood
  • Install Firestone APP 180 Modified (White Granule Surface)
  • Cost: $3,590
  • Five-year guarantee against leaks

I really appreciate your guidance and expertise.



I would go with epdm any day but would recommend tpo over it even same type of system but better grade plus you wont have the issue of rubber (epdm) disintegrating from tar contact, from the tpo. the rubber contracter should be able to do the tpo as well.

Thank you for the advice! Would the TPO be significantly more expensive? I’m probably going to have to replace at least some of the plywood decking, given the roof’s age, so I’m already expecting to be pushing my budget on this.

**TPO **
Is more expensive.

Is typically a commercial roof system and not often used on residential work. Which means if you need repairs down the road it may be more difficult to secure knowledgeable personnel.

Is cheap as hell.

EPDM is roofer friendly and most of your residential roofers have good knowledge of the product. It’s used extensively
on both residential and commercial systems.

**APP **(torch applied)
Is a very robust system. Good for heavier foot traffic etc.

Is both a commercial and residential system.

Is imo outdated. It’s also illegal in many areas because too many clueless “roofers” have burned customers homes
to the foundation during torch application.

APP (trowel applied)
This is garbage and should be outlawed. It’s basically a roll shingle pushed into tar. Kick anyone that suggests it off your property immediately.

In short, go EPDM unless you have heavy foot traffic. If you do have heavy foot traffic consider using something like VAST Pavers over a drainage mat.

Thanks for the note! No, there’s no foot traffic up there at all really. I guess we could stick some chairs out there as we can walk out of the second floor bedroom windows onto the flat roof (it’s a one-story addition in back attached to a two-story house), but I was always too worried about falling through some rotting plywood to try. :slight_smile: But no the only time I’d expect foot traffic is if we needed to trim some of our neighbor’s overhanging branches or to make roof repairs.

Actually i’ve found that TPO and EPDM are pretty much identical in price now a days. I personally would still chose a EPDM. Your climate really doesn’t dictate whether a white or black roof will be good or bad. As long as there is not a over abundance of penetrations a TPO may actually be cheaper.

I’m against torch roofs in every way. Too many things can go wrong with them, mostly from the installer.

First thing that impressed me with the EPDM bid was the .060. We normally use .045 for residential in Texas. Thats on a hard deck (plywood,OSB). The .O60 is what is spec’d on commercial around here. If you tool around the net, you’ll find that Firestone says that EPDM is a 50 plus year product. I believe it.

The real odd thing about the EPDM bid is the labor warranty. This product when installed correctly, should be the last time you see your roofer for a long time. The one year warranty on labor is a little substandard. I see no reason why you shouldn’t ask for at least 5yrs.

EPDM is really cheap. TPO is good if you can afford it.

Thanks everyone!

APP vs EPDM at almost identical cost ??? Where’s the oddball in that equation ? I’m having a loss of comprehension understanding how they could be even close in price… No brainer… A 5-10 year roof or a 20-30 year roof for almost the same cost… Go EPDM and keep the trees trimmed way back, plus get more estimates for the same material… EPDM can be white or black and TPO can be any number of different colors… What stood out is the .032 mill edge, great long life product, almost unheard of in a residential application…

There are lots of flat roofing options and everyone has an opinion. There are no one size fits all solutions to low slope roofing, and for some roofers they think there is. Some guys ONLY install EPDM or ONLY install mod bit. We used to install alot of modified bitumen and we are getting away from it. We have always dabbled in EPDM, and still do, though it’s not our primary low slope offering it does have a place. When we began phasing out Modified Bitumen, we began to replace it with TPO. No we are replacing TPO with PVC. … ofing.html

Modified Bitumen? There is nothing wrong with the product. But lots of roofers start fires, even very highly respected and safe roofers. I don’t want to take that chance anymore and try as best as possible to always leave the torches in storage when ever possible. Also any roof will leak from seams and penetrations first, and that’s a proven fact. Modified bitumen has 3’ rolls, so seams every 3’. Furthermore consumers tend to think modified is modified is modified and that’s simply not the case. How can you compare a 10 year smooth black to a 20 year 4 ply granulated? They are not the same. I don’t sell cheap, I sell quality, I don’t sell 10 year roofs.

EPDM the membrane its’ self will last darned near forever. A 60 mil epdm is fairly durable and slightly puncture resistant, especially if there is a high density cover board. By the way, alot of guys install modified bitumen without a cover board (directly over wood) and this is a huge no no. We always install all our membranes with a cover board of some kind. EPDM is the easiest roof I’ve ever installed. However the adhesives in the seams tend to fail in 10-15 years. That’s why on warranted jobs, the manufacturers are requiring self adhering seam tape. It can get costly on small roofs. Plus EPDM is often black.

Why do I like Thermoplastic like PVC and TPO? When installed properly it’s the best I have found. But there is opinion, and some evidence, that TPO is an inferior product, prone to failure for various reasons. I’d still prefer install TPO over modified however. I tell my customers, “If you want a 15 year roof, let’s go TPO and if you want a 20 year roof let’s go PVC.” There is more to it than that, but that blanket statement seems to fit most of the roofs I look at.

Comparing estimates, scope of work and quality of materials will dictate price. Are both being torn off? What is being done to address insulation? Is ventilation a requirement, if so who is doing what? What are the system specifications, 10-30year depending on system and installation method? (Don’t compare a 10 year roof to a 30 year roof.) By far the details are the most important and often most neglected. What kind of edge detail? What kind of drainage? Are flashings being reused, replaced? If reused throw away the bid. If replaced, HOW? Get it ALL in writing. A standard proposal document I present to my home owners for flat roofs is generally 2-3 pages long spelling out exactly what we plan to do, how we plan to do it, and what products we plan to use. If you like you may post your proposals here for us to point out the differences. **They can’t be that simple, can they?! **

The APP estimate seems like he’s doing a 12 year roof with no cover board. No drip edge? Is he torching right to the wood?! $3 a sq ft is $96 per sheet for plywood.

Pricing is the LAST thing you should consider when comparing quotes. Again, Scope of work and Quality of material will dictate price. In other words look at what you are getting, not what you are spending.

Make sure each contractor is licensed if necessary in your municipality. Call the licensing board to make sure the license is valid. Make sure they have workmens compensation as well as General Liability insurance. Get a certificate with yourself named as the certificate holder. Check the BBB, while most contractors will agree the BBB is a friggin joke, one thing that can’t be disputed is their complaint history. When checking the BBB only look at complaint history, if they have had alot of complaints you may ask yourself if you want to gamble on being the next. Perform a simple google search for the company by name, perhaps a few keyword variations like “grumpy’s roofing company problems” and see if people are talking bad about the company. Also look for the estimator by name, you’d be surprised what you can find out about people on the internet. For example would you want to do business with someone who has a picture of them self smoking crack on their facebook page? Just sayin’ … ractor.htm

As for the pricing being so similar, pricing is often in the logistics on small jobs like this. I would expect any system to cost very similar on 6 squares of roofing.