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County Antrim · Northern Ireland

Cavity insulation for new builds and extensions in County Antrim

Cavity insulation for new builds and extensions across County Antrim, survey-first: a written result for every wall and a fixed price before work. For new walls the cavity is insulated as it is built, using full-fill mineral wool batts or partial-fill boards fixed to the inner leaf.

Bricklayer building a new cavity wall with mineral wool batts between the block and brick leaves

Free survey in County Antrim

Tell us about the property and we will arrange a free survey and a fixed price.

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Cavity insulation for new builds and extensions across County Antrim

We cover 7 towns in County Antrim, including Belfast, Lisburn, Newtownabbey, Carrickfergus, Ballymena and more.

Exposure matters for every cavity wall. Parts of County Antrim face some of the heaviest wind-driven rain in the UK, especially exposed coastal and upland sites. Here the survey is stricter: some walls suit only certain certified systems, and some should not be filled at all.

For semi-detached and terraced homes in County Antrim, cavity barriers are fitted where your wall meets your neighbour's so the fill stays on your side. Where a County Antrim property has an extension or a conservatory, we check how the old and new walls meet, because that junction is often missed.

Building control in Northern Ireland

In Northern Ireland, inserting insulation into an existing cavity wall needs a building control application to your council before the work. We make sure the application route is agreed and confirmed in writing before any drilling starts.

Funding in Northern Ireland

  • The Affordable Warmth Scheme, run with the NI Housing Executive, helps owner-occupiers and private tenants with a total gross household income under £23,000; cavity wall insulation is a priority measure where suitable.
  • The NI Sustainable Energy Programme funds energy efficiency schemes through participating providers.
  • ECO4 does not apply in Northern Ireland.

Sources: Building Control NI: frequently asked questions; Belfast City Council: what are the building regulations; NI Housing Executive: Affordable Warmth Scheme; Utility Regulator: NI Sustainable Energy Programme.

Extensions that join an older house

Where an extension meets an existing cavity wall, the junction is a weak point. We can borescope and fill the existing wall at the same time so the old and new walls perform together.

What is included

  • Batts or boards to the specified U-value
  • Clean-cavity working
  • Trays, closers and stop ends as drawn
  • Coordination with your bricklayers
  • Photo record for building control

Cavity insulation for new builds and extensions prices in County Antrim

Cavity insulation for new builds and extensions guide prices
Cavity insulation for new builds and extensions guide pricesGuide price
Full-fill batts supplied and fitted, per m²£9–£16
Partial-fill boards supplied and fitted, per m²£14–£26

Prices are shown before any VAT; the VAT treatment for new-build work is confirmed on your quote. Guide ranges only: the fixed price is confirmed in writing before any work starts, and anything that could not be seen at survey is agreed with you first.

The steps for cavity insulation for new builds and extensions in County Antrim:

  1. Get in touch

    Online, by phone or WhatsApp, whichever suits you.

  2. Survey visit

    The surveyor checks each wall and looks into the cavity where needed.

  3. Your result in writing

    What we found, what it means, and a fixed price if work is needed.

  4. Booked work

    Carried out by the installer named on your quote, with their scheme registrations.

Last reviewed 19 October 2026.

Cavity insulation for new builds and extensions in County Antrim: questions

Do you cover all of County Antrim?

Yes. We cover 7 towns across County Antrim, including Belfast, Lisburn, Newtownabbey and Carrickfergus, and the villages around them. Island and remote addresses are surveyed by arrangement.

Is there VAT on cavity insulation for new builds and extensions in County Antrim?

Building a new home is usually zero-rated when supplied by the builder; supply-only materials are standard-rated. The VAT treatment is confirmed on your quote.

Are there grants for insulation in County Antrim?

In Northern Ireland, the Affordable Warmth Scheme helps eligible households with a gross income under £23,000. We cannot promise funding, but we will point you to the right official route.

Is my County Antrim home too exposed for cavity insulation?

Parts of County Antrim get some of the heaviest wind-driven rain in the UK, so the survey is stricter and some walls are better left unfilled. The survey records the exposure of each wall before recommending a material, or recommending against filling.

Cavity insulation for new builds and extensions in nearby areas

Book a free survey in County Antrim

Free survey with an install quote. Written result. Fixed price before any work.