Running CH pipework in insulated stud wall.

[dan1w]

I'm having my garage converted into a living room and connecting two rads up myself.

An insulated (xtratherm) stud wall is going up over the existing single skin brickwork and I was planning on running the pipework from the roof void down the wall.

The studs are 70mm and insulation 50mm. The builder wants to maintain an air gap behind the insulation and has a preference for the insulation being flush with the plasterboard. I intend to run 15mm copper and with clips that doesn't leave much of an air gap if any.

What's the done thing here? Running in front or behind the insulation? Also, due to windows the pipe runs potentially wouldn't be straight and running the pipework in front would put it at risk of getting drilled in the future, yet running it behind would mean having to puncture the insulation.

 

[John D v2.0]

Generally you'd want to run your hot pipes inside the insulation, otherwise you'll have to put decent thickness insulation on the pipes as they're most of the way to outside.
Same applies if they're above the ceiling insulation or below the floor insulation, but generally you'd have more space to wrap the pipes.
Things passing through the insulation isn't a disaster d long as you seal round it.