Insulation · Group G
Airtightness, thermal bridging and finishing — seal, insulate, ventilate.
Draught-proofing, airtightness, thermal bridges, acoustic insulation, fire-stopping and ventilation.
Overview
About airtightness, thermal bridging and finishing
Insulation works best in a home without draughts — and a well-sealed home needs the right ventilation to stay dry. This group covers the details that make the difference: draught-proofing, airtightness, thermal bridges, pipe and tank insulation, acoustic insulation, fire-stopping and ventilation.
Draught-proofing is a quick win for almost every home. The rest is usually done alongside a main insulation job, so the whole home works together.
Every service in group G
7 ways we can help
Thermal bridging fixes
Insulated lintels, reveal and cill insulation and thermal breaks that stop cold spots and mould.
Airtightness works
Membranes, tapes, grommets and sealants at joints, service holes and floors.
Draught-proofing
Sealing doors, windows, letterboxes, hatches, floorboards and unused chimneys — every home's quick win.
Pipe, tank and cylinder insulation
Pipe lagging, cylinder jackets, radiator reflector panels and loft tank insulation.
Acoustic insulation
Sound insulation in floors, party walls and ceilings.
Fire-stopping and cavity barriers
Cavity barriers and fire-stopping installed with EWI, cavity and loft works.
Ventilation with insulation
Trickle vents, extract fans, PIV or MVHR so a better-sealed home stays dry.
Prices
What airtightness and draught-proofing costs
| Measure | Mid-terrace | Semi / end-terrace | Detached | Bungalow | Flat / block |
|---|---|---|---|---|---|
| Draught-proofing | £250–£600 | £300–£800 | £450–£1,100 | £300–£800 | £200–£500 |
Indicative ranges for London and the South East, supplied and installed, including VAT, before grants. Updated 11 October 2026. A survey confirms your final price.
| Service | Typical range, installed |
|---|---|
| MVHR system with airtightness works | £6,000–£10,000 |
Indicative ranges for London and the South East, supplied and installed, including VAT. Updated 11 October 2026. A survey confirms your final price.
0% VAT on energy-saving materials
Insulation, solar panels, batteries and heat pumps installed in homes in Great Britain are zero-rated for VAT until 31 March 2027. Windows and doors are not included.How it works
Survey, check, install, guarantee
- 1
Survey
A surveyor visits, measures and checks the construction — borescope for cavities, moisture and ventilation for roofs — then confirms what suits your home and the final price.
- 2
Condensation risk and PAS 2035, where needed
Internal and external wall insulation and roof conversions get a condensation risk analysis for each build-up. Funded and whole-house jobs follow PAS 2035, starting with a retrofit assessment.
- 3
Install
We install to the manufacturer's or system holder's specification, with one named contact throughout. Scaffolding, making good and any building control are set out in your quote.
- 4
Guarantee and paperwork
You get the paperwork for what's installed — the guarantee from the relevant body or manufacturer, explained before you sign, plus any building control or competent-person certificates.
Grants and savings that may help
- ECO4Closes in 73 days
Up to fully funded; paid by energy suppliers per measure
Grant via local councils (£960m nationally in 2026/27)
- Social Housing Fund
Landlord-led bids
Saves 20% VAT
- Local schemes
Varies
Eligibility depends on your circumstances and is confirmed by evidence and the funder or council.
Grant schemes change often. Our 60-second checker uses the current rules and tells you plainly whether you're likely, possibly or not eligible — and we never call funded work free without saying it depends on eligibility.
Check my eligibilityQuestions
Airtightness and Draught-Proofing: common questions
Can a house be too airtight?
Not if it's ventilated properly. The rule is 'build tight, ventilate right': seal unplanned leaks, then provide controlled ventilation with trickle vents, extract fans, PIV or MVHR.
What's the quickest way to make my home warmer?
Draught-proofing doors, windows, floorboards, the loft hatch and unused chimneys is low cost, quick and makes rooms feel warmer straight away.
Why do I get mould on cold walls?
Mould grows where warm, moist air meets a cold surface — often at thermal bridges like lintels and reveals, or where ventilation is poor. Insulating the cold spots and improving ventilation tackles both causes.
Begin your project
Price your insulation in two minutes
Prices by property type, with grants and 0% VAT applied where they fit. A survey always confirms the final figure.