My Garage Conversion

[dylsi]

When I moved into my current house four years ago the attached garage had been lined with plasterboard and the floor had been insulated and boarded (and DPC fitted). I assume the previous owner was going to convert to a habitable room.
This year I've had the garage door replaced with a window (see pics).
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Building Control was involved from the start, and the inspector required the wall below the window have insulation in the cavity and also behind the internal plasterboard. This was covered by the door-to-window replacement contract I had with the local window installers.
During the inspection, the inspector commented that he needed to know if there was insulation behind the plasterboard that lined the room (installed by previous owner) and also how much insulation was on the floor. Just my luck that the previous owner didn't install any insulation behind the plasterboarded walls, but had installed 2" of polystyrene insulation below 20mm interlocking flooring.
[GALLERY=media, 4905][/GALLERY] [GALLERY=media, 4906][/GALLERY] [GALLERY=media, 4907][/GALLERY]
How much insulation should there be behind the wall plasterboards (I have cavity walls and insulation in the cavity) and also how much should there be on the floor. I am thinking of using skirting radiators such as Thermalskirt or similar.

Thanks

 

[garyrayne123]

if the walls are cavity filled you shouldn't need to use insulating plasterboard.

Do you know cavity width and insulation specification.

If it is necessary to use insulating plasterboard then use a Gyproc Themaline or similar. 35-50mm should be ok as its only a thermal upgrade.


there are loads of options

You could also use a high performance insulation board like celotex and 12.5mm gyproc wallboard. I think a VCL will be required but not 100% on that.

More insulation in floor will be beneficial use a high performance board rather than EPS (however if BC are happy no need to fix)