Pitched Roof to Flat Roof, issue?

[Suffolk_J]

Afternoon all,

 

I've been reviewing our prelim drawings for our timber frame build, one area I'm looking at is how the pitched roof will meet the flat roof. Build is essentially a bungalow with mezzanine used for bedroom/dressing/bathroom. Plan is for warm deck with EDPM and extensive living roof but will the pitched roof effectively meeting the flat roof (attached) cause an issue? Can't visualise how it will work and initially thought there would be a drop down and the pitched roof would have independent guttering. I'd rather look ahead and change this now than deal with a bigger headache... if it is one!

 

Many Thanks.

[Mr Punter]

You would normally run some ply up the pitched section and continue the flat roof waterproofing up under the tiles.  In your case it will be quite a long up the slope way because you need insulation and build up for the green roof.  Not sure is you need a fall with the system you are using?  You could do with a detail drawing of this because you have quite a lot going on and need to make sure everyone understands how to make it work.

[Conor]

We built up 300mm of ply up the roof, flat roofer made a 300mm flashing for this and brought the roof covering to this. The roofing felt lapped over the flashing and in our case we had GSE roof trays meet it, but other wise you'd just bring your tiles/ slates down to the valley. 

 

The flat roof falls back to the valley and rainwater continues down the pitch roof to the gutter. Ours was a dormer

Edited September 6, 2021 by Conor

[Suffolk_J]

Thank you both, I think I'm comfortable enough that we can make this work without having to incur fees for changing the timber frame design. My key concern was if I'd missed something that would present a problem with no solution, as long as there is a viable and practical solution I can work through the detail.

 

Cheers.