EPDM flat roof transition to pitched roof

[Peter500]

I can't think of a good way to transition from a flat roof to a pitched roof. I found this article https://www.rubberroofingdirect.co....-roof-slopes-onto-the-flat-roof-fleece-backed, but would this design seems to have lost the gap between the trusses, so surely water could build up behind the batten?

The only other way I can think of doing this is with cross battening to maintain the gap, but I've already tiled the pitched roof on one side, so it would be a big change (or I would probably have issues with the ridge tile not sitting level etc.?

I'm planning to use Resitrix (heat welded EPDM) for the flat roof. The tiled part of the roof is large format tiles (gauge around 300mm) and the membrane is drapped between trusses. PIR Insulation is between the trusses but it's only 40mm as it's an unheated garage and it leaves a 25mm gap for the membrane. The side with the transition is also only 2 tiles, but the other side is much longer.

 

[Peter500]

I've done some Googling and thinking and came up with this idea . I haven't put the EPDM in the illustration, but it would cover the OSB and go under the eaves tray. The eaves tray would also have the added benefit of preventing the tiles from doing any damage to the EPDM.

I would probably put a bird guard along the front too. The only thing that worries me about the bird guard is that it would penetrate the rubber, so could cause a leak. What are people's thoughts on the bird guard here, and are they really needed?

Any other thoughts about the design? The illustration isn't perfect, I'd probably extend the OSB a little further, and of course, the underlay would sit on top of it.

 

[freddiemercurystwin]

Yes that's the gist, Google 'flat to pitched roof detail'.

 

[cdbe]

If you search "EPDM and pitched roof" on here there is a thread. I presume your concern (as was mine) is that the layboard stops the membrane/EPDM "sagging between the rafters/below the battens to allow a drainage path? In my case there was only one row of tiles on the layboard and as there isn't a fascia to carry the bottom end of the tile you need something (a packed up batten) - this will allow any water to drain. I think where others had higher up battens on the board they packed a little bit, eg with some lead.

 

[martygturner]

Follow the NHBC pitched roof abutment detail ... https://nhbc-standards.co.uk/2019/7...and-balconies/7-1-10-detailing-of-flat-roofs/

Its what the BC will be looking for.