Keep the Heat In. Keep the Bills Down.

Cavity Wall Insulation is one of the most cost-effective ways to improve your home’s energy efficiency — with minimal disruption and immediate impact.

Rear exterior view of a brick house featuring a modern paved patio area, a wooden pergola with seating, glass French doors, and a small brick outbuilding under a clear blue sky.

What is Cavity Wall Insulation?

Many Irish homes built from the 1930s onward were constructed with two external walls and a gap (cavity) between them.

Cavity wall insulation fills that gap with high-performance insulating material, helping your home retain heat, lower heating costs, and feel noticeably warmer — often immediately.
The result? Warmer walls, reduced heating bills, and a more comfortable home — all in a day’s work.

Why choose Cavity Wall Insulation?

Instant Comfort
Keeps heat inside and cold air out
Energy Savings
Cut heating costs by up to 25–30% beads
Eco-Friendly
Reduce carbon emissions and improve your BER
A close-up shot of a property surveyor in a white shirt inserting a diagnostic probe into a drilled hole in a red brick wall while checking a smartphone interface during a cavity wall inspection.

Is My Home Suitable?

We recommend a free survey to confirm suitability, but generally:

  • Homes built from the 1930s and early 2000s
  • Walls with unfilled cavity gaps (typically 50mm+)
  • External walls in good structural condition
  • Detached, semi-detached, or end-of-terrace houses

Homes with solid walls (pre-1970s) may be better suited to External Wall Insulation.

A BlueBuild technician wearing a protective respirator mask, safety glasses, red ear defenders, and a high-visibility vest operating a heavy-duty Hilti rotary hammer drill to core an openings in a concrete block wall.

Our Installation Process

Our expert installation is fast, clean, and typically completed in just one day.
Here’s how it works:

  • We carry out a detailed wall assessment to confirm suitability
  • Small, discreet holes are drilled in the external wall
  • High-performance insulation beads are injected to fully fill the cavity
  • All drill points are carefully sealed to match the original finish
A BlueBuild installer using specialized equipment to inject cavity wall insulation into a property.

Extraction & Removal of Old Insulation (When Required)

Not all homes have clean, empty cavities. Some contain old, poorly performing, or failed insulation — such as mineral wool, or degraded foam.

Before we install new insulation, our team can fully assess and remove unsuitable material when needed. This ensures:

  • The cavity is clean and unobstructed
  • New insulation fills the space evenly and effectively
  • Moisture issues caused by old insulation are eliminated
  • You receive maximum thermal performance from your upgrade

Our extraction service includes:

Cavity inspection using borescopes and thermal imaging
Professional removal of old or damp insulation
Safe disposal in compliance with environmental standards
Preparation of the cavity for fresh bead injection

If your home has cold patches, damp spots, or previously failed insulation, extraction may be the first step in restoring comfort and efficiency.

A smiling woman wearing a headset takes notes with a pen while looking toward her open laptop at a wooden desk in a bright office environment.

Northern Ireland Grants for Cavity Wall Insulation

Homeowners in Northern Ireland may be eligible for support through a range of government-backed energy efficiency schemes — helping to reduce or even fully cover the cost of installation.

Available support can include:

  • NISEP (Northern Ireland Sustainable Energy Programme) – including fully funded options for eligible households
  • Affordable Warmth Scheme for lower-income homes
  • Potential support through local council or energy supplier initiatives

Our team will:

Assess your eligibility during your free survey
Guide you through the most suitable funding options
Handle the application process where applicable

👉 Find out if you qualify for fully funded insulation on our Residential Grants page.

Frequently Asked Questions on Insulation for your home

We’ve answered some common questions to help you with any concerns

Not at all. It’s a low-impact process with no interior work needed. All holes are sealed to match your wall.

Installed correctly, cavity wall insulation can last for the life of the building — 30+ years.

That’s what our free survey is for. We’ll carry out wall inspections and even use a borescope if needed.

Yes — and it’s highly recommended for best results and full grant benefit.

Our Installation Process

1
1
Free Home Energy Survey

To check wall type and insulation potential

2
2
Grant Support

We prepare and submit your application

3
3
Non-invasive Installation

Using small drill points

4
4
Bead Injection

Insulation fills the cavity wall completely

5
5
Sealing & Cleanup

Wall finish restored to match original

Most installations completed in 4–6 hours.

Hear from Our Customers

Google Reviews
Rated 4.6 out of 5 stars on over 100+ reviews

Ready to Keep the Heat Where It Belongs?

Get professional, affordable insulation installed quickly — with grant support included.

• IAA -Registered Contractor
• Fully Insured & Certified Installers
• 13+ Years’ Experience
• Customer Satisfaction Guarantee