Is EPDM suitable for a part tiled part flat roofed dormer?


25 Feb 2010
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United Kingdom
I'm currently side extending and loft converting a bungalow on a, where possible, DIY basis. I have a couple of dormers to build, one has a relatively simple flat roof. The second has a largely tiled pitched roof with hip but to stop it extending above the ridgeline is topped with a small (approx 2x1m) flat roof. I'm considering using EPDM for both flat roofs primarily because the of the lack of joins needed and it looks relatively DIYable compared to torch on felts or GRP.

Question is: How would I create the transition from flat roof to the Redland 50 double roman tiles. I have seen pictures of this being done with felt being layered over the top row of tiles and then ridge tiles being bedded over the join leaving a couple of gaps to allow the flat roof to drain. Is this arrangement possible with EPDM, can you get it to adhere to profiled concrete tiles or would I need to transition to lead flashing 1st? Any ideas?
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Lead apron over tiles with flat roof drip detail on top of apron.
Thanks Alastair, If I understand that correctly I would end up with a visible flat roof 'hovering' above the pitched roof?

ideally I would like to hide the flat roof. Could I use the arrangement I have sketched below? Can you get EDPM to adhere to lead and would bedding ridge tiles over it damage the membrane? Is the formflash necessary?

You need to extend the roof deck as tight as possible to the tiles, so you have no sagging of the epdm.
The epdm can be glued ( contact adhesive ) direct to the tiles, or better still that has been mentioned, fit a lead flashing over the tiles.
Router out a step in the edge of the roof board, ( thickness of lead ) so as the epdm can sit over without any high spots.
You can bed ridge tiles on but, I would leave decent gaps if this is where the roof is draining of, the gaps could get blocked.
If you done a scallop finish on the front over lapping lead it would look okay without bedding on any ridge.
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EPDM will stick to new clean lead with bonding glue. Will the ridge tiles be seen? If not use a dry ridge system, nice and light and won't damage the epdm

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