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EPDM how to

2662 Views 12 Replies 7 Participants Last post by  Tom Struble
Firstly , I am a contractor and have been doing renos for the last 20 yrs so I do have a range of knowledge on houses. My situation is I have a rental cottage with a nearly flat (probably 1 / 12 pitch) roof 20 x 25 that is currently tar and gravel and seen better days. There is some soft spots that I need to fix and also tear off all the old roofing.Recently I scrounged from a commercial installation an EPDM roof that was up for 3 yrs before it was removed for an expansion of the building. I have a 1 piece no seams section big enough for the cottage roof and would only need to add one plumbing vent boot to the sheet.In its commercial instalation it was loose lay with a layer of drain rock but I have seen in residential it is glued down. Is there a reason or benefit to either system and if glued is it straight down to plywood or is there some other layer between it and the plywood.The last thing I want to do is skip an important step and have to redo all my hard work( I hate that)
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Skip, welcome to CT, please complete your profile, then go to the intro page and tell the guys a little about yourself and your proffessional exp, thanks GMOD:thumbsup:
Skip- Rocks are cheaper than bonding adhesive/ On the down side, if something pokes a hole in the rubber, lots a luck finding it.

Glue it if possible..... Benefits- won't shrink, easy leak repair, easy inspections,won't collect dirt,rocks are heavy...............etc.........
profile updated...
workorfish- so I don't need to worry about UV or other exposure then?
The roof is below three large pine and cedar trees and gets a good 6" of debris each year so no rocks would make it much easier to cleanup.
Good to go, good luck! NO wrinkles!!
Well I dove rite in and started to scoop the debris off. I completely shoveled it off 3 yrs ago and now it is almost 10" deep in some spots, lots of trees around it.It resembled a thick layer of peat and was surprisingly fluffy and most of it light.

I used OSB for me to walk on as it unfortunately seems to have several soft spots
I chopped into one soft area and found ship lap running across 2" x 6" ceiling joists(not 1 1/2 x 5 1/2). the ceiling is vaulted so on the bottom of this is vapor barrier and gyproc with fiberglass insulation. Not what I thought was there. My thoughts would be that I have to strip the ship lap, strap it (for cross ventilation) then new ply. I was considering adding a layer of rigid foam insulation as well to make it more efficient and reduce the cold(condensation) on the joists.
does that seem correct, any suggestions?

Once I reach my 15 posts I'll post pics of my progress:thumbup:
If the ship lap is shot, by all means strip it out of there. I'm not sure exactly what you're up to with strapping for cross ventilation. If there's no air gap above the insulation, it probably wouldn't hurt to create one. But in my area, we fasten the sheathing directly to the joists.

Once the sheathing's down, add a layer of fiberboard, secured with screws and stress plates (3" galvanized washers). The rubber is then glued down onto that surface. Any roofing supply company in your area should be able to set you up with what you need to complete the job; normally they're very helpful.
My thoughts would be that I have to strip the ship lap, strap it (for cross ventilation) then new ply. I was considering adding a layer of rigid foam insulation as well to make it more efficient and reduce the cold(condensation) on the joists.
Give the membrane a good look over before you apply it. Unless you were the one to take it off, who knows how it was handled. Holes can be patched easily as long as you can find them.

Get plenty of help when you go to set it, and if you have never done it before a 20' sheet can be tough to work. Might want to try a practice run at how to lay it down before you glue it up. Once it's down it won't want to move.
I've glued laminate down and its just as unforgiving about 2nd tries.
as to the strapping, I have always assumed in a vaulted area(no attic) moisture can get trapped in each joist area and have no exit which causes rot. Cross ventilation gives a way for moisture to travel to vents to the exterior and ensure it stays dry
Go to there are free training videos.

My preferred method is mechanically attached for single ply. It goes down quicker and cheaper than fully adhered. We haven't done any balalsted but have bid several. Ballasted goes down ultra quick and cheap and very very economical on large buildings, however not every building can support the weight so is not a good retro-fit choice.

installation of epdm over plywood is acceptable if the plywood is fastened using screws, soemtimes stainless are required. I am not a fan of this application and have only done it once. IMO install at least a 1/2" fiberboard if you are not looking for any R value. Or else if you do desire R value look into Polyisocyanurate.
build a peak over it:thumbsup:
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