What it is

For a suspended timber floor — floorboards over a void, common in pre-1950s homes — we fit insulation between the joists from below (via the void or cellar) or from above where boards are lifted, and seal the perimeter to kill draughts. For a solid concrete floor, insulation is added above the slab as part of a wider refurbishment. Either way the aim is the same: stop cold air and heat loss at floor level.

Why it matters for 2030

Ground floors can account for around a tenth of a home's heat loss, and suspended timber floors are notoriously draughty. Underfloor insulation is a fabric-first measure that improves both the EPC and comfort, and it pairs naturally with loft and wall insulation to lift a property over the band-C line.

Which homes suit it

Homes with a suspended timber ground floor and an accessible void or cellar are the easiest and best-value cases. Where there is no access the boards are lifted, which suits a void period between tenancies. Adequate under-floor ventilation is kept so the timber stays dry. Solid-floor insulation is usually only worthwhile during a larger renovation.

Grants that apply

Included under the Warm Homes: Local Grant for eligible tenants and ECO4 (to 31 December 2026), and zero-rated for VAT until 31 March 2027. Grant funding counts towards your £10,000 cost cap. Checked on the grants page.

How we do it

Coordinated to PAS 2035, installed to PAS 2030 by our accredited partner LAMTANS Engineering, lodged with TrustMark. Fixed price from our own book, as part of your free assessment.

Cold floors in an older let? The free 2030 Compliance Assessment checks the floor type and access and prices the work.