Is Your Old Cavity Wall Insulation Failing? Signs It Needs Extracting
Cavity wall insulation should be a fit-and-forget improvement. In most homes it is. But a minority of older installations — particularly blown fibre fitted many years ago, sometimes on walls that weren’t suitable — have started causing problems.
If your walls were filled and something doesn’t feel right, here’s what to look for.
Signs your cavity insulation has failed
- Damp patches on inside walls, often low down or around windows, that don’t come from an obvious leak
- Mould in corners of outside walls, especially in bedrooms
- Walls that feel cold to the touch even though they’re supposedly insulated
- Damp that’s worse after driving rain, particularly on the most exposed side of the house
- Bowing or staining on the outer brickwork in severe cases
Why it happens
The most common causes are:
- Wet insulation. Fibre that gets soaked by rain penetrating the outer leaf can bridge the cavity and carry moisture to the inside wall.
- Settlement. Over time some fibre slumps, leaving the top of the wall uninsulated and cold.
- Debris. Mortar and rubble left in the cavity during building can bridge it and wet the insulation.
- Unsuitable walls. Some properties on very exposed sites simply shouldn’t have been filled with that material.
Extraction and refill
Where the old material has failed, the fix is to extract it. Bricks are removed at intervals and the insulation is pulled out of the cavity, then the cavity is checked and cleared of debris.
Once the walls have had a chance to dry, the cavity can be refilled with a better-suited material. Our cavity wall insulation uses EPS bead, which doesn’t absorb water and doesn’t settle, so the same problem doesn’t come back.
If the outer brickwork is very porous or exposed, keeping it dry with a breathable ProPerla wall coating can also help protect the wall going forward.
Don’t assume it’s the insulation
Damp has plenty of other causes — failed pointing, blocked gutters, a bridged damp-proof course or condensation from poor ventilation. A proper survey looks at all of these, so you don’t pay for extraction when the real problem is a leaking downpipe.
Common questions
Is it a big job? It’s more involved than a fill, but it’s done from outside and doesn’t need anything moving inside.
Will the damp go once it’s removed? If the insulation was the cause, yes — walls typically dry out once the bridge is removed.
Do you cover my area? We’re based in Warrington and work across Widnes, Runcorn, St Helens, Newton-le-Willows, Golborne, Leigh, Culcheth, Lymm, Frodsham, Northwich and Greater Manchester.
Free survey for damp cavity walls
We’ll find out what’s actually causing the problem and tell you straight. Over 30 years’ experience, all work and materials guaranteed.
Call 073 5919 5156 or get a quotation today.
