Insulating outbuilding

[Gjtrl855466]

I have a 4.3m x 3.4m outbuilding, single skin block & some brick. Floor has DPM under concrete, I’ve also done a DPL round corners & then self level. I have also gone round an drilled plenty of air vents.

The plan:
I have got plenty of 2x1 batten lengths so batten around room (DPM behind & 1inch off ground).
Sit 50mm PIR celotex 70mm screws ON TOP of batten creating cavity (air vents in use) with foil tape for joints.
Vapour barrier or vapour control layer? Over the top of celotex.
Foil backed plasterboard on top screwed on top with 80mm screws.
Keeping the 1 inch gap consistently throughout build.
Skirting with air vents on top.

Few questions, what kind of vapour barrier am I needing?
Also I have these kind of pillars that are proud to adjacent wall by 100mm best way to work around them?

Any feedback would be great

 

[foxhole]

What’s the heat source?

 

[Notch7]

How are you finished the building externally?

I don’t quite understand where the cavity is venting -why would you have air vents on top of skirting?


Im not clear about the order but it seems like you are putting battens on wall, then PIR which is fixed in place with screws - that won’t hold very well. Then VCL and foil back plasterboard.



Personally if it was me, I would put battens on the outside then clad so there’s a cavity outside, then put PIR tight to wall with 50 x 25 battens flat then plasterboard - which you could do anyway in my opinion, just use DPM up the walls first.

how are you detailing floor to wall junction as you will need to prevent any damp on wall getting across into floor - in a house with brick block the cavity extends below the floor by 225mm

 

[Gjtrl855466]

How are you finished the building externally?

I don’t quite understand where the cavity is venting -why would you have air vents on top of skirting?


Im not clear about the order but it seems like you are putting battens on wall, then PIR which is fixed in place with screws - that won’t hold very well. Then VCL and foil back plasterboard.



Personally if it was me, I would put battens on the outside then clad so there’s a cavity outside, then put PIR tight to wall with 50 x 25 battens flat then plasterboard - which you could do anyway in my opinion, just use DPM up the walls first.

how are you detailing floor to wall junction as you will need to prevent any damp on wall getting across into floor - in a house with brick block the cavity extends below the floor by 225mm

Hi mate,
So the brick vents would help allow moisture to escape from the cavity which I’ve created between the battens and Celotex. By continuing the 1 inch gap across the floor and adding some kind of vent between skirting allows fresh air in and out the cavity. Probably way OTT I know.

I will struggle to add the cavity on the exterior walls as whoever built the outhouse left about 700/800mm around the sides and back to the surrounding fences so not much room to work with…

Sorry I’ve not heard of detailing floor, there’s a DPM below the concrete?

 

[Gjtrl855466]

What’s the heat source?

I will be adding an electric rad.