How to use the Cavity Wall Cost Calculator
- Enter wall area in m² (length × height, minus openings).
- Select outer leaf (face brick type), insulation option and inner leaf block.
- Add openings/lintels (count) and any finish allowance if required.
- Review totals (inc VAT) and export or copy the result.
Use this for budgeting. For tenders or specification-led work, request a QS estimate with BoQ, prelims, overheads and profit, and risk allowances.
Typical cavity wall costs (UK, per m²)
- Standard face brick + insulated cavity + 7N block inner leaf: £180–£260/m² (typical £220) including VAT
- Higher-spec facing (handmade/engineered) or coloured mortar: add £10–£35/m²
- Full-fill mineral wool vs PIR partial-fill: similar labour; material cost varies by spec and thickness
Rates include wall ties, DPCs, cavity closers and fixings. Exclude foundations, scaffold, structural steel, render/paint, and internal plaster/insulation unless selected.
Worked example: 20 m² cavity wall with one opening
Wall area 20 m² × £220/m² = £4,400 including VAT.
Add one standard lintel and cavity closers: £120–£220 depending on span/spec.
Indicative total: about £4,520–£4,620 including VAT, subject to brick selection and access.
What drives cavity wall cost
- Facing brick & bond: handmade or engineered bricks, specials, wide joints or feature bonds add labour and waste.
- Insulation spec: PIR vs full-fill mineral wool; thickness and lambda value affect material cost.
- Openings & lintels: more cuts, damp trays and cavity closers add time and components.
- Access & height: scaffold lifts, tight sites and winter working increase prelims.
Scope assumptions
Outer leaf 102.5 mm facing brick to standard mortar, insulated cavity with ties at specified centres, inner leaf 100 mm block, DPCs at abutments, cavity closers at openings, tidy down. Excludes foundations, slab, structural steel, internal plastering, services, decoration and external scaffold unless selected.