Energy and insulation

Cavity wall insulation

Pumping insulation into a cavity, where the wall is suitable for it.

Post a task Cavity wall insulation by county

Whether this needs a licence in Ireland

Ireland

No licence required

SEAI Registered Contractor (needed only for grant-funded work)

Taken from the statute below; not yet reviewed by a lawyer

Sustainable Energy Authority of Irelandwww.seai.ieChecked 11/10/2026

Cavity wall insulation: what the job involves

Blowing insulating beads or fibre into the gap between the two leaves of a cavity block wall through small holes drilled in the outside, then filling the holes. Most Irish houses built from the 1970s to the early 2000s have cavities that can be filled in a day.

Also asked for as: pumped insulation · bead insulation walls · cavity fill · wall insulation grant · SEAI cavity wall grant

How the job is usually done

Check that the walls are cavity walls and suitable: cavity width, existing partial fill, signs of damp, exposure to driving rain and the condition of the outer leaf.
Inspect the cavity with a borescope at several points and check that wall vents, gas flues and boiler vents will not be blocked.
Drill injection holes in a set pattern in the mortar joints or render around the house.
Inject the bonded bead or fibre so it fills the cavity from bottom to top, around windows and doors and up to the roof line.
Fill and colour-match the holes, and sleeve or check the wall vents so ventilation is kept.
Check for gaps with the borescope, and record the work for the system certificate and the grant.

Cavity wall insulation: what is included

Usually included

Survey and borescope inspection of the cavity
Drilling, injection and filling of the holes
Sleeving or checking wall vents and flues
The system installer’s certificate or guarantee

Usually not included — agree it separately

Repairs to cracked render or pointing found during the survey
Removing an existing failed fill
Painting the walls after the holes are filled
Extra ventilation in rooms that need it

Materials and who supplies them

Bonded polystyrene bead or blown mineral fibre with an NSAI Agrément certificate, supplied by the installer
Mortar or render filler matched to the wall
Vent sleeves where needed

How long it takes

Usually one day for a typical house; longer for a large detached house or where some walls need extra checks.

When to book

Best done in a dry spell, since drilling and filling render needs dry weather and the walls should not be saturated.

Cavity wall insulation: the rules in Ireland

What the official sources say, checked against them on the date shown. A summary, not legal advice — follow the link to read the rule itself.

For the grant, the work must be done by a contractor on SEAI’s register for that measure, and only after the grant offer is accepted — work started before approval is not grant-aided.
Applies to: the homeowner and the contractor
Sustainable Energy Authority of Ireland · hes.seai.ie · Checked 9 October 2026
The grant must be claimed within eight months of the offer, and a BER by a registered assessor is needed after the works before SEAI pays.
Applies to: the homeowner
Sustainable Energy Authority of Ireland · seai.ie · Checked 9 October 2026
Building work on a home is charged at the reduced VAT rate of 13.5% by a VAT-registered business, unless materials make up more than two-thirds of the price.
Applies to: the contractor
Revenue · revenue.ie · Checked 9 October 2026
Filling a cavity must not block the permanent ventilation that rooms with open-flued or solid-fuel appliances need; Building Regulations guidance on ventilation applies.
Applies to: the contractor
Building Regulations Part F (Department of Housing) · gov.ie · Checked 9 October 2026

Grants

SEAI cavity wall insulation grant
€1,800 for a detached house, €1,300 for a semi-detached or end-of-terrace house, €850 for a mid-terrace house and €700 for an apartment.
Who qualifies: Owners of homes built and occupied before 31 December 2010, using an SEAI-registered contractor, with approval before work starts.
seai.ie · Checked 9 October 2026
Enhanced rates and the Warmer Homes Scheme
Higher “enhanced” grant rates apply to first-time buyers who bought on or after 1 January 2025, people on qualifying welfare payments, and homes with a HAP or RAS tenancy. Homeowners on certain welfare payments in homes built and occupied before 2006 may get a fully funded upgrade instead.
Who qualifies: Owners who meet the scheme’s conditions; the fully funded route has a waiting list SEAI quotes at about 15 months.
seai.ie · Checked 9 October 2026
SEAI One Stop Shop
A registered One Stop Shop manages a whole-house upgrade to at least a B BER, handles the grants and deducts them from the price up front.
Who qualifies: Homeowners planning several upgrades together that bring the home to at least a B BER.
seai.ie · Checked 9 October 2026

What cavity wall insulation costs, and why

What jobs on Talqero came to

Not enough comparable jobs yet to publish a range here. Talqero shows a price range only once at least five comparable jobs, agreed prices or offers exist — a range from fewer would describe a handful of jobs, not the market. Post your job and compare the offers you get.

What affects the price

Wall area and the number of elevations
Cavity width and whether there is already a partial fill
Access: extensions, conservatories and tight side passages
Wall finish, since rendered and brick walls are drilled and made good differently
Vents and flues that need sleeving
VAT: building work on a home is charged at the reduced rate of 13.5% by a VAT-registered business — unless the materials come to more than two-thirds of the price, when Revenue’s two-thirds rule applies the goods rate to the whole job. Ask whether a quote includes VAT.

Paperwork to ask for at the end

The system installer’s certificate or guarantee, naming the product and its NSAI Agrément certificate
An itemised invoice and the SEAI declaration of works if a grant is claimed
A post-works BER for the grant

Safety

Bead can escape into rooms through gaps around pipes and sockets; keep children and pets out of rooms on external walls while injecting.
Rooms with an open fire, stove or gas appliance must keep their wall vents; never block them afterwards.
Walls facing heavy driving rain, especially on the west coast, need checking before any fill.

Cavity wall insulation: before you hire

Questions to ask a tradesperson

Are you on SEAI’s register for cavity wall insulation?
Which product will you use, and is it NSAI Agrément certified?
Will you check the cavity with a borescope before you start?
What guarantee comes with the fill?
How will you keep my wall vents working?

What you can do yourself

Not a DIY job: it needs injection equipment, a certified system and an installer approved for that product.

What to put in your task

What type of home is it?
Do you know what the external walls are built from?
Roughly when was the house built?
What is the outside of the walls finished in?
Are you applying for the SEAI grant?

Photos that help

Each side of the house, from far enough back to see the whole wall
Wall vents, boiler flues and meter boxes on the outside walls
Any cracks, damp patches or blown render
The edge of a window opening, where the wall thickness can be seen

Cavity wall insulation by county

Choose your county for cavity wall insulation close to home.

Energy and insulation

Need cavity wall insulation? Describe the job.

Post it once, free. Professionals near you reply with their own price and when they could start. You choose, and pay them directly.

Post a task

Questions about cavity wall insulation

Does cavity wall insulation need a licence in Ireland?

No licence is required for this work in Ireland (source: www.seai.ie). Ask instead for references and photographs of similar jobs.

How do I know if I have cavity walls?

Most block houses built in Ireland from the 1970s onward have a cavity. Measured at a window or door, a cavity wall is usually about 300 mm or more thick. An installer confirms it with a borescope through a small hole.

Can cavity insulation cause damp?

It can, if it is put into a wall that is unsuitable, badly pointed or exposed to driving rain. That is why a survey comes first and why certified products and approved installers matter.

Will it make a mess inside?

All the drilling is from outside. A little bead sometimes escapes through gaps around pipes or sockets, which is easily vacuumed up.

Often booked with cavity wall insulation

Insulation installers