Property suitability surveys
A check of wall construction, cavity width, rain exposure, existing fill and brickwork condition before any price is given or any hole is drilled.
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Cavity Wall Insulation Installers: Surveyed, Injected and Made Good
As cavity wall insulation installers we fill the gap between the two leaves of your outside walls so less heat escapes, but only after checking that your walls are suitable for it.
About 1/3of the heat lost from an uninsulated home escapes through the wallsSource: Energy Saving Trust
260mmbrick walls thicker than this usually have a cavitySource: Energy Saving Trust
0.55 W/m²KU-value threshold when an existing cavity wall is filledSource: Building Regulations Approved Document L
Loft & Insulation
Cavity Wall Insulation with EcoBuild Contractors
Most houses built in the UK from the 1920s onwards have outside walls made of two separate leaves of masonry with a gap between them. In many older cavity homes that gap was left empty, and air moving through it carries warmth straight out of the building. As cavity wall insulation installers, we fill that void with an insulating material, cutting heat loss through the walls without any change to the rooms inside.
Not every cavity should be filled, which is why our work starts with a survey rather than a drill. We confirm the wall type, measure the cavity width, assess how exposed the walls are to wind-driven rain, check for any existing fill and look closely at the condition of the brickwork, pointing and gutters. If your walls are not a good match, we will say so and suggest another way to insulate them.
When the walls are suitable, the installation itself is quick and done entirely from outside. Where appropriate we use blown mineral wool products such as Knauf Supafil, injected through small holes in the mortar joints and then made good. An average house is usually finished in a day. Some households may qualify for funding through government schemes; we can check whether you might be eligible, but it is never guaranteed.
What we do
Cavity wall insulation work we carry out
Borescope cavity inspections
A small inspection hole lets us look inside the cavity with a borescope to see its width, cleanliness and any rubble or old insulation.
Blown mineral wool insulation
Where suitable we use products such as Knauf Supafil, a blown mineral wool that fills the cavity evenly and still lets the wall dry out.
Party wall cavity barriers
On semi-detached and terraced homes a barrier is fitted at the boundary so the insulation stays inside your property and out of your neighbour's wall.
Air brick and vent sleeving
Air bricks serving underfloor voids, flues and room vents are sleeved through the cavity so the new fill cannot block them.
Brickwork and drainage checks
Cracked render, worn pointing, blocked gutters and leaking downpipes are flagged for repair first, because water getting into a filled cavity is the main cause of trouble.
Homes and commercial buildings
We insulate cavity walls in houses, flats and commercial premises, with the same suitability checks on every building.
Why it is worth it
Benefits of cavity wall insulation
Reduced heat loss
With the cavity filled, far less warmth escapes through the outside walls, and the inner face of each wall stays warmer to the touch.
Improved energy efficiency
Filled cavity walls are recorded on an Energy Performance Certificate and can lift your home's rating alongside loft insulation.
Potential heating cost savings
Because the heating has less lost warmth to replace, it runs for shorter periods, which can bring your energy bills down.
No disruption indoors
Everything happens from the outside, so there is no plastering, redecorating or moving furniture.
Is my house suitable for cavity wall insulation?
The first question is whether you have a cavity at all. Brick walls more than about 260mm thick, measured at a window or door frame, usually have one, and bricks laid entirely lengthways in a stretcher pattern are another sign. Solid walls are thinner and normally show a mix of long and short brick faces. Timber-framed and steel-framed houses can look like brick from the outside, but their cavities should not be filled.
Exposure matters just as much. Homes on hillsides, near the coast or with a wall facing the prevailing wind take a lot of wind-driven rain, and in the most exposed spots some fills are not appropriate. We also check that the brickwork is sound, the cavity is wide enough to fill evenly and clear of mortar droppings and rubble, and that the damp-proof course will not be bridged. If any of those checks fail, filling the cavity could draw damp across to the inner wall.
What can go wrong, and how we avoid it
Most complaints about cavity wall insulation trace back to a handful of causes: walls that were too exposed for the material used, damaged brickwork or gutters letting water in, rubble in the cavity bridging the two leaves, or vents that were covered over. Any of these can lead to damp patches on internal walls, often appearing a winter or two after the work.
Our survey is designed to catch those issues before installation, and the material is chosen to suit the wall. After the work, keeping gutters clear, repointing when the mortar wears and fixing cracked render keeps the outer leaf weathertight, which is the best protection for a filled cavity.
Our process
How the job runs
- Property suitability surveyWe confirm the wall type, measure the cavity width, assess exposure to driving rain, check for existing fill and inspect the condition of the brickwork.
- DrillingOnce any repairs are done and vents are sleeved, small holes are drilled in a set pattern along the mortar joints, never through the face of the bricks.
- Insulation injectionBlown mineral wool, such as Knauf Supafil where suitable, is injected through each hole until that section of the cavity is full.
- Making goodEvery hole is filled with mortar matched as closely as possible to your existing joints, and we confirm vents and flues are clear before we leave.
FAQ
Cavity Wall Insulation questions
How long does cavity wall insulation take to install?
An average semi-detached or terraced house is normally done in a day, sometimes in half a day. Larger detached homes can take longer.
What insulation do you put in the cavity?
For most brick cavities we use blown mineral wool, with products such as Knauf Supafil where suitable. The survey decides the material, because cavity width and rain exposure affect which fill is appropriate.
Do I need permission to fill my cavity walls?
Inserting insulation into a cavity wall is building work under the Building Regulations, so it has to be notified to building control. We make sure that happens, and listed buildings may also need consent from the council.
Could my cavity wall insulation be funded?
Some eligible households may qualify for funding through government energy efficiency schemes. We can check your circumstances, but funding depends on the scheme rules at the time and is not guaranteed.
Will my house look different afterwards?
Only very slightly up close. The drill holes are roughly the size of a coin and are filled with mortar matched to your joints, so they are hard to spot from the street.
Free, no-obligation quote
Get a free quote for cavity wall insulation
Tell us a little about your property and the work you need. Add a few photos if you can, it helps us give you an accurate price sooner.
Related services
Often booked with cavity wall insulation
Internal Wall Insulation
For solid-wall houses with no cavity. We line external walls from the inside with insulation, a vapour control layer and a fresh plaster finish ready to decorate.
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Loft Insulation & Boarding
Old insulation removed, new mineral wool laid to around 270 to 300mm, then a raised storage floor, ladder and hatch fitted so the loft works properly.
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Damp Proofing & Treatment
Damp surveys that find the real cause, then the right fix: damp proof course injection, penetrating damp repairs, replastering and cellar tanking for homes and businesses.
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