Best approach for resurfacing flat roof?

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Msupsic

Marc S.
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Hello. We've got a 75 year-old flat-roof home in PA that is need of a new roof. Trying to figure out the best approach.

The roof was last done ten years ago, the roofing contractor used Certainteed stick-down (adhesive) modified bitumen. The product is starting to fail in some places, the ceramic surface is wearing off. The roof leaks, namely where it meets the outside walls or the chimney feature (see photos).

We've had several quotes done, with a range of materials. EPDM, TPO and lastly, torch-down.

Most quotes are for ripping everything down to the wood, replacing bad wood, adding insulation and new surface. I've also had several suggestions to cut the aluminum siding up 6" from the bottom so they can run the material further up the outside walls. This is the source of most of the leaks.

Here are the options I'm wrestling with:

Most expensive: EPDM and TPO
Rip everything down to the subroof, replace old wood, add pitched insulation, wider drain holes. Cut aluminum siding off at bottom and trim off.

Mid-priced: 2 ply Torch Down
Rip everything down, replace old wood, insulation, new drains and do a 2-ply torch-down.

Cheapest: 1 ply Torch Down
Leave current roof in place, and go over top with 1-ply torch-down

Any thoughts? Thanks.
 

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Snoonyb

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Torch down will work, however, what is the R-value of the existing insulation, and are you intending to upgrade it?
 

oldognewtrick

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If you have moisture under the existing surface, you will compromise the integrity of any roof system you install over it. Most municipalities will only allow for a total of two layers of roofing.
There is no material warranty from any manufacturer of EPDM when installed on a residence. It's a commercial product only.

Do it right, do it once, tear it off, replace any rotten decking, add insulation board if needed and have a qualified roofer install a complete system. That includes flashing, drip edge and make sure there's no areas pounding water. Pounding water after 48 hours can void any material warranty.
 

kok328

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I'd go with a Duro-Last roof. You have to be certified by the company to install/repair.
It was originally made as a swimming pool liner; so you can imagine it's durability and ability to withstand "ponding".
 

oldognewtrick

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I'd go with a Duro-Last roof. You have to be certified by the company to install/repair.
It was originally made as a swimming pool liner; so you can imagine it's durability and ability to withstand "ponding".
They are pricey.
 

WyrTwister

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Not trying to be a smart mouth . But truly , the best solution ( maybe not the cheapest ) is to put up trusses and a conventional roof .

God bless
Wyr
 

NeilG

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Not trying to be a smart mouth . But truly , the best solution ( maybe not the cheapest ) is to put up trusses and a conventional roof .

God bless
Wyr
As someone with an aging flat roof, I'd agree with this. I'm going to see what it would cost to put a sloped roof on my house.
 

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