EPDM corner flashing

[geraldthehamster]

I'm going to be helping a friend DIY an EPDM flat roof that will join a bungalow at the eaves. The bottom row of concrete tiles is in the way, so wil be removed where the flat roof intersects the bungalow roof. The plan is also to board over the rafters under the second row of tiles, and carry the EPDM up over it, under the existing roof felt, and replace the second row of tiles on top.

The flat roof does not go the full width of the bungalow, so the bottom row of tiles will be retained either side.

Can someone advise on the flashing detail for these corners? Can it be done in EPDM or should it be done in lead? If someone could describe how to do this, or point to a diagram, I'd be very grateful.

Cheers
Richard

 

[Mw Roofline]

You'll need to do it in quick seam formflash. Just google quick seam formflash corner detail and you should get a few YouTube videos. That's if I think I know what you mean.

 

[geraldthehamster]

You'll need to do it in quick seam formflash. Just google quick seam formflash corner detail and you should get a few YouTube videos. That's if I think I know what you mean.

Brilliant, thank you. I was trying to remember what that stuff was called.

So would I also board under the last bottom row tile that is alongside the flat roof, formflash that to the top and cheek of the flat roofed portion, then replace the tile on top?

Can formflash be fixed directly to OSB, or will it only bond to primed EPDM?

[Edit: I think I've answered that in the affirmative from one of the Youtube videos]

(I was waiting for someone to ask for pictures; my drawing is terrible but I can try if any of what I'm trying to describe isn't clear)

Cheers
Richard

 

[Mw Roofline]

Yes a pic would help, you CaN only formflash onto primed epdm

 

[geraldthehamster]

Yes a pic would help, you CaN only formflash onto primed epdm

So you have to use the Quickseam SA flashing if directly onto board, as in this video? Sorry, just want to make 100% sure to get the right products.

Cheers
Richard

 

[Mw Roofline]

Yes, I didn't know about that first SA flashing part. (I just sell the stuff I don't always see how the fitters do it)

 

[geraldthehamster]

Well, in case anyone is interested, we've done this job - L-shaped flat roof of about 25 m2, joining a higher sloping roof on one side, draining to a sloping lean to roof on the adjacent side, and having parapets to the other two sides. We have a very small number of minor blisters (not too noticeable), and the flashing could be neater, but generally I'm pleased with the result. I'm amazed how malleable the uncured Formflash (or rather, the equivalent from Rubbaseal) is. The only thing I'd do differently next time is use spray adhesive for the upstands that required contact adhesive, instead of glue from a tin. I don't think I've ever been so sticky.

EPDM sheet, flashings and adhesives worked out about £18 per square metre of roof.

Cheers
Richard