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bcbud3 10-20-2013 03:16 PM

Torch on roof alternatives...
I currently have a low slope roof with torch on roofing. The time has come to get quotes for a new roof. What is the opinion on single-ply systems such as PVCs and EPDM rubber vs the asphalt torch on stuff..

If i do go with the torch on what things should i be looking for to be installed. A friend said i need the paper on sheathing, sub layer and then the top layer...does that sound right? He also mentioned something about bringing the torch on layer over top of the facia board not just up to the top of it (not sure if i explained correctly) before getting covered with the aluminum drip cap (not sure of proper name)...

Another concern i have is with lack of venting at the peak of the roof. I have enough at the bottom to allow the air in but not enough to let it out. I would like to get a ridge vent put in. I had an estimate coupe years ago and the installer described it as cutting a slot in the roof (about a foot wide? can't remember). Then building a small frame (i think 3-4" high vertically) to put on a ridge cap. Does the sound about right? Any other things to know or ask?

Thanks for help

Windows on Wash 10-21-2013 07:23 AM

I wouldn't personally do a torch roof in any application.

Single ply roofs are good depending on installed application and you might be able to metal on in some situations as well.

You don't vent flat roof with a ridge vent.

bcbud3 10-21-2013 06:55 PM

what would you recommend for a low slope roof?

Windows on Wash 10-22-2013 05:33 AM

Totally depends on the applications, roof design, surroundings, etc.

I like metal when I can specify it.

jagans 10-24-2013 12:56 PM

You need to be more specific than just Low Slope.

Is this a compact roof system? That is, do you have your thermal insulation in the roof system? (The roof System is from the deck up)

What is the exact makeup of the roof assembly (The roof assembly includes the structural members, air space below, plus the roof system)

As Eric (WOW) says, you have a lot of options. If you decide to use Modified Bitumen, I would use an SBS based system in two plies, and at least the first ply would be set in cold process adhesive, as a torch is a real good way to burn your house down.

Modified bitumen should always be installed in at least two plies of SBS Mod Bit, One glass reinforced, and one polyester reinforced, or two or three plies of Type IV glass felt in hot asphalt and an SBS Polyester Reinforced granular surfaced cap sheet.

It was never designed to be installed as a single Ply roof, but a lot of Hacks do it. :censored:

RVR 10-26-2013 09:24 AM

We like Poly Glass SA base, and top sheet for low pitch applications.
Self adhering peel, and stick.

bcbud3 10-26-2013 09:20 PM

had a couple of quotes now from what a couple of roofers and have been told it looks like my modified bitumen roof is in good shape. It was a brand that was originally from italy back in the day (25 years ago).

Two roofers have said it looks like it was applied directly to the plywood underneath. All have said there is no visible water damage or soft spots to worry about.

All roofers have given me quotes that include tearing old layer off and putting on 2 or 3 ply setups.

One roofer said that a new layer could be applied directly over top of the existing layer (some sort of primer to be put down first). He told me he could tear everything off down to plywood and apply everything again and charge me more (like all the others) but it was unnecesary. He said that any wrinkles in the roofing could be slit, nailed flat and new layer put over top making sure seams overlapped. He said he would still offer the same 10 year warranty for either installation method.

Any reason not to go with this? The original roof is 27 years old (no leaks) and gets constant sun, no trees or foilage on it.

AndyWRS 10-27-2013 10:39 AM

They can see it we can't, if they are telling you its in good shape then i see no reason to do anything. But 27 years is a long time, modbit around here doesnt last that long and we have a mild climate.

When its time to roof you should tear off all existing layers and start from scratch. Just torching a layer over the existing is not a new 2 or 3 ply system. If i was doing torch down i would do 3 ply, if your current roof is already 2 or 3 ply you may not be allowed to put 3 more. I am not sure if the building dept considers a 3 ply one or 3 layers of roofing. We are limited to two total here. It never comes up because we always tear off.

The peice of mind you will gain from tearing off and starting from scratch is worth the cost of the tear off.

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