Running a soilpipe through the roof void

Yukster · 3 Mar 2016

I would like to run a soil pipe through a pitched roof void so i would be grateful for your advice to help me work out if i can get it done and still have have enough room for insulation. The roof void is 180mm deep and the soil pipe is 110mm in diameter. How much gap do i need to leave for ventilation between the insulation and the roof tiles? Would 10mm be enough? if so that leaves 30mm of insulation over and under the soil pipe. Does that sound like it is enough?

Will.. · 3 Mar 2016

50mm required air gap.
I don't understand why you're running a soil pipe between rafters? Is it for venting purposes or does it form part of the 'wet' side of the system?

Yukster · 3 Mar 2016

Will.. said:
50mm required air gap.
I don't understand why you're running a soil pipe between rafters? Is it for venting purposes or does it form part of the 'wet' side of the system?

It is a part of the 'wet' system. My bathroom is on the first floor and my kitchen and extension is right underneath it. I am trying to find a route for the soil pipe from the upstairs toilet to the manhole outside so that it is out of sight. The alternative is to box the soil pipe in the space underneath the extension roof which will be unsightly so i'd like to avoid that if i could

chappers · 3 Mar 2016

just break the insulation over the pipe along it's length and add 50mm of ridged insulation under the ceiling ties of the extension

Yukster · 4 Mar 2016

chappers said:
just break the insulation over the pipe along it's length and add 50mm of ridged insulation under the ceiling ties of the extension

Thanks Chappers. Can you please explain a bit more. What is ridged insulation? is it something like Kingspan or Celotex? Are you suggesting to insulate above or under the soil pipe? Thanks

chappers · 4 Mar 2016

yeah celotex or kingspan,
Insulate your roof space as normal apart from where the pipe runs and only insulate under the pipe leaving your air gap above the pipe and then make up the insulation under the ceiling in the extension with 50mm

Yukster · 5 Mar 2016

Thanks! This is the drawing I plan to send to my bco for approval. Any comments welcome

chappers · 7 Mar 2016

should be fine, is the ceiling below already finished, if not just use 25mm insulated plasterboard to reduce any cold bridging you may get due to the reduced insulation around the pipe.

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Running a soilpipe through the roof void

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