Insulation systems
External Wall Insulation
EWI systems that insulate solid walls externally and finish them in a warranted render topcoat.
External wall insulation is the most effective upgrade available to a solid-walled property. Around a third of heat loss in an uninsulated solid-wall house goes straight out through the walls, and because there is no cavity there is nothing to fill. EWI fixes insulation board to the outside face, wraps it in a reinforced basecoat and mesh, and finishes it in a render topcoat — so the wall gets warmer, the fabric stays inside the insulated envelope, and condensation risk drops.
The detailing is what separates a good EWI job from a callback. Reveals have to be insulated and sealed, the eaves and verge usually need extending to cover the new wall thickness, sills need replacing or extending, and every penetration needs a proper closure. We survey all of it before quoting, because the details are where the heat and the water actually get through.
When it is the right choice. Choose EWI on solid-wall, no-fines or non-traditional construction where you want a genuine thermal upgrade rather than just a new finish.
Specification at a glance
| Typical guide price | £135–£210 per m² supplied and installed |
|---|---|
| Applied thickness | 50-150mm insulation plus render system |
| Curing / drying | Staged, 7-10 days total |
| Guarantee | 25 years |
| Category | Insulation systems |
Guide prices are indicative only and exclude scaffold, stripping and repairs. Your written quote follows a free survey.
What is included
- EPS, mineral wool and phenolic boards
- 50mm to 150mm thicknesses
- Mechanical and adhesive fixing
- Reinforced basecoat with mesh
- Silicone or acrylic topcoat
- Window and door reveal detailing
- Eaves and verge extensions
- Fire-rated mineral wool options
- Cuts heat loss through solid walls
- 25-year system warranty
Get a quote for external wall insulation
Tell us about the property and we will call you back to arrange a survey.
Related services
What happens next
Four steps from enquiry to finished wall
Free survey
We visit, test the substrate, measure up and identify what caused any existing failure.
Written quote
An itemised fixed price with the system named, materials specified and scaffold included.
Booked in
An agreed start date, scaffold arranged, and a clear run of days set aside for your job.
Finished and guaranteed
Site cleared, scaffold struck, guarantee documents and system warranty issued.
Coverage
External Wall Insulation by county
We carry out external wall insulation across all 74 counties below. Pick yours to see local detail.
East of England
South East
South West
North West
North East
East Midlands
Yorkshire
London
West Midlands
Wales
Scotland
Northern Ireland
FAQs
External Wall Insulation — your questions
How much does external wall insulation save?
On a typical uninsulated solid-wall semi it commonly cuts wall heat loss substantially and makes the biggest single difference to comfort. Actual savings depend on the existing construction, heating system and how you use the house.
Will EWI make my house look different?
The walls become 70-200mm thicker, so reveals get deeper and the eaves usually need extending. Done properly it looks intentional; done cheaply it looks like a box.
Do I need planning permission for EWI?
Often not on a standard house, but you will if it is listed, in a conservation area, or if it alters the appearance significantly. We advise before starting.
Can EWI cause damp?
Correctly specified it reduces damp risk by keeping the wall warm. Problems come from poor detailing at reveals, sills and penetrations, or from using a non-breathable system on a wall that needed one.
How long before I can paint new render?
Through-coloured systems need no painting at all. Sand and cement should cure for around 28 days before masonry paint goes anywhere near it.
Do you take a deposit?
For most domestic jobs we take a deposit to cover materials and scaffold, with the balance on completion. Terms are set out clearly in the written quote.
Can you match my existing render?
Usually, yes. We colour and texture match as closely as we can, though weathered render never matches a fresh batch exactly — we will be honest about how visible a patch will be.
Thinking about external wall insulation?
Book a free survey and we will confirm whether it is right for your walls before you commit.