How to install internal wall thermal insulation


1. Original wall
  • Solid non-cavity wall, north facing and cold to the touch
2. Adhesive applied to wall
  • The adhesive used is British Gypsum Dri-wall adhesive, mixed using a refina paddle mixer to a thick consistency. The wall is marked with pencil lines showing where the edge of each board will be so the adhesive can be applied in sections.
3. PIR Insulated 37.5mm plasterboard bonded to wall.
  •  The aluminium straightedge shown in the photo is used to tap the boards into position and keep them flat without any high or low spots. A spirit level held against the straightedge helps to ensure the boards are plumb against the wall. Plastic shims (not shown in photo) are inserted below each board to raise and support the plasterboard off the floorboards.
4. Joints taped using scrim.
  • The boards are also mechanically fixed to the existing wall using 120mm fixings, 3 on the top and 3 along the bottom of each board. The fixings are installed after the adhesive has set so as not to pull the boards out of plumb.
5. Two coats British Gypsum multi-finish plaster skim to finish.
  • The skirting was re-used and fixed with construction adhesive and counter-sunk 120mm fixings. Ronseal 2 part wood filler was used to cover the countersunk screw holes and a bead of decorators caulk run along the top of the skirting completes the job.


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