How much does the average cavity insulation cost?

[LucidEnergy]

Seeing as people said £300-£500 for the loft, how much will cavity walls cost to insulate?

[Ecolocker]

It all depends on the size of your property. Cavity wall insulation can be fraught with potential issues if not done properly so doing it on the cheap could well end up causing you a wealth of issues down the line (internal damp being the most common and costly repercussion).
That said however, you can get it done fairly cheaply but the payback period is considerably longer than simply lagging or increasing the insulation in your loft and draft-proofing, I personally feel the figure of 19% saving on your energy bill that's generally quoted when talking about the benefits of cavity wall insulation is a bit high, and there isn't much evidence to support his figure because there are to many variables involved.

Normally you can expect a single wall to cost in the region of £300-£500, that said, it can be more if there is any remedial work needed to correct issues beforehand if the surveyor / installation team does not inspect the cavity thoroughly beforehand with a camera be very worried..

Hope that helps.

RB