EPDM parapet edge detail

[geraldthehamster]

I've tried to attach a poor drawing of a proposed edge detail for a paparet on an EPDM roof. Please could anyone tell me if this looks like a fair way to do it?

The roof and parapet and EPDM are installed. Wall is timber frame clad in OSB and breathable membrane. Battens, shiplap, fascia and any edge trim have yet to be installed (edge trim would be a metal one from an EPDM supplier). EPDM is stuck down all the way to the edge and overhangs loosely by about 100mm.

Air can enter at the bottom beneath the cladding, so I thought an air gap at the top would promote air flow. Alternatively it might be bad thing because of driven rain. What do people think?

Should I consider not having the fascia and just take the cladding to the top?
If anyone would do this completely differently, I'm open to suggestions.

Many thanks
Richard

 

[^woody^]

Buy the proper plastic edge and kerb trim. Its much easier and avoids those nasty right-angles which are prone to splits.

You do need an air gap, but consider an insect screen too.

Fascia should project to protect the cladding and cast water off it, the more the projection the better but no less than 50mm normally.

 

[freddiemercurystwin]

You should have a strip of epdm bonded over the top of the fascia and the parapet epdm to cover those holes you're about to make in the flashing and parapet epdm.

 

[geraldthehamster]

Buy the proper plastic edge and kerb trim. Its much easier and avoids those nasty right-angles which are prone to splits.

You do need an air gap, but consider an insect screen too.

Fascia should project to protect the cladding and cast water off it, the more the projection the better but no less than 50mm normally.

Thanks. I was going to use these, do you approve?

http://www.rubber4roofs.co.uk/shop/metal-edge-trim-rubber-roofing
http://www.rubber4roofs.co.uk/shop/metal-trim-corner-connector

Cheers
Richard

 

[geraldthehamster]

You should have a strip of epdm bonded over the top of the fascia and the parapet epdm to cover those holes you're about to make in the flashing and parapet epdm.

The edge of the EPDM that covers the roof and comes up over the parapet will be bonded over the top of the fascia, and the edge trim will go over that. The edge trim is meant to be fixed through with pins, that are supposed to be self-sealing, though I suppose I could glue the edge trim instead of pinning it. But I wouldn't want to put more EPDM on the top of the edge trim. I'm probably misunderstanding you completely.

Cheers
Richard

 

[freddiemercurystwin]

Well if you're comfortable that the fixings are self sealing then fine but I'd be doing this

 

[geraldthehamster]

Well if you're comfortable that the fixings are self sealing then fine but I'd be doing this

OK, point taken - perhaps I'll use some 6" flashing tape on the top of it. That diagram is for an asphalt system, though, if that makes any difference.

Cheers
Richard

 

[freddiemercurystwin]

My bad but the principle is the same:

Taken from the Firestone EPDM manual.

Though I acknowledge they do a fix on trim as you have originally proposed. But something riles with me when you go fixing dozens of fixings through a waterproof membrane. You only need one to fail and you have a problem.

 

[geraldthehamster]

My bad but the principle is the same:

View attachment 82833 Taken from the Firestone EPDM manual.

Though I acknowledge they do a fix on trim as you have originally proposed. But something riles with me when you go fixing dozens of fixings through a waterproof membrane. You only need one to fail and you have a problem.

It's a fair point, and it's straightforward to flash over it.

OK, so what I'm taking on board from you helpful chaps is a decent overhang on the fascia, consider an insect screen, and flash over the trim fixings. Other than that, what I have looks OK?

Cheers
Richard

 

[^woody^]

Have a look at the edge trims at www.permaroof.co.UK

The type I was thinking of, which I used at mine a few years ago seems to no longer be available - it was like a P in section with the straight bit fixed vertical down the fascia, and the square bit sealed on top of the roof edge. They do have a similar type though.

These look a lot better than messing with kerbs, timber and metal trims. And as FMT mentions, the fixing is not on the top, so no issues with potential failure.

 

[geraldthehamster]

Have a look at the edge trims at www.permaroof.co.UK

The type I was thinking of, which I used at mine a few years ago seems to no longer be available - it was like a P in section with the straight bit fixed vertical down the fascia, and the square bit sealed on top of the roof edge. They do have a similar type though.

These look a lot better than messing with kerbs, timber and metal trims. And as FMT mentions, the fixing is not on the top, so no issues with potential failure.

This looks similar to what you're suggesting:

http://www.rubber4roofs.co.uk/shop/sure-edge-kerb-trim-2-5m

I suppose there's no reason why the metal trim needs to be fixed through the top (unless it's pre-drilled). I prefer the look of the metal trim.

You said earlier:

Fascia should project to protect the cladding and cast water off it, the more the projection the better but no less than 50mm normally.

I couldn't achieve that with either of those trims, so I'd still need the timber fascia, no? The timber in my diagram is all associated with the cladding, rather than the EPDM per se.

Cheers
Richard

 

[^woody^]

You can pack a fascia out with some 6x1 rough tanalised timber, then fix a plastic fascia capping board, and then fix the edge trim.

This does away with the need to form an upstand/kerb, and keeps the EPDM flat removing potential for it to spilt, or debond and lift from the roof edge as it goes up and over that kerb.

 

[geraldthehamster]

You can pack a fascia out with some 6x1 rough tanalised timber, then fix a plastic fascia capping board, and then fix the edge trim.

This does away with the need to form an upstand/kerb, and keeps the EPDM flat removing potential for it to spilt, or debond and lift from the roof edge as it goes up and over that kerb.

Well, I don't think I need a kerb as such - I'm capping the edge of the parapet, which is already a pretty big upstand in its own right. And the reason for the timber fascia is that I'm not fond of uPVC on display. It sort of defeats the object of cottagey timber windows and wooden cladding, to slap a bl00dy great chunk of plastic on the top.

Cheers
Richard

 

[freddiemercurystwin]

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