How cavity wall insulation extraction works
When it is done properly, extraction is a specialist job using industrial vacuum equipment. Checkatrade summarises a typical non-destructive sequence as follows (Checkatrade):
- Survey – confirm the insulation type and condition, and that extraction is actually needed.
- Drilling – small holes (often around 22mm) through external mortar joints at regular intervals, or removal of bricks at low level depending on the method.
- Extraction – industrial vacuum equipment pulls the material out of the cavity.
- Making good – holes filled and repointed to match the existing mortar; bricks reinstated where removed.
- Disposal – material removed from site. Standard mineral wool or bead usually goes to general waste; UF foam needs specialist disposal.
- Check – a follow-up inspection to confirm the cavity is clear.
How long does it take?
Checkatrade says whole-house removal usually takes between one and three days (Checkatrade). Drying time for damp plaster and any redecoration sit on top of that.
Can I do it myself?
No. Removal needs specialist equipment and training. DIY attempts risk leaving material in the cavity and causing further problems (Checkatrade).
After extraction
- Leave the cavity empty until walls are dry, if damp was present
- Ask about suitable refill options, or external wall insulation, only after diagnosis and drying
- Keep photographs and reports – useful for lenders, buyers and any guarantee file
Altering or disturbing insulation can affect guarantee validity. CIGA states the guarantee is not valid if the insulation has been altered or disturbed (CIGA). If you still have cover, speak to the installer or CIGA before instructing private extraction.