Group B · Cavity and internal walls
Bay, dormer and reveal insulation
Insulating bay walls, dormer cheeks and window reveals to remove cold spots.
Priced after survey
Bay, dormer and reveal insulation
Every job like this is different, so we measure first and give you a fixed written quote. The price depends on:
- The area and access
- What's there now and its condition
- The system and finish you choose
No obligation — your survey confirms what suits and what it costs.
- Best for
- Period homes, with window replacement
- Guarantee or standard
- Manufacturer's guarantee, confirmed in your quote
- Time on site
- Often a day or two, ideally alongside new windows.
- Typical price
- Priced after survey
What it is
What is bay, dormer and reveal insulation?
Insulating bay walls, dormer cheeks and window reveals to remove cold spots.
Best for: Period homes, with window replacement.
Who it suits
Which homes is bay, dormer and reveal insulation suitable for?
Is my home suitable?
Pick your property type for a straight answer on bay, dormer and reveal insulation.
Guidance only — every home is different, and a survey confirms what suits yours.
Houses
- Detached house
- Semi-detached house
- End-of-terrace
- Mid-terrace
- Townhouse
- Mews house and cottage
- Detached bungalow
- Semi and terraced bungalow
- Chalet and dormer bungalow
- Period home
- 1930s home
- Post-war and ex-council house
- Non-traditional / system-built
- Listed building or conservation area
- Farmhouse, barn conversion or rural home
- New build or self-build
Flats and blocks of flats
Commercial and public buildings
Usually suitable Depends — a survey confirms
Not usually suitable for 1 property type
- Park and mobile home — Park and mobile homes need specialist systems, which we arrange through a partner rather than standard measures.
Materials and brands
What we use
Insulating bay walls, dormer cheeks and window reveals to remove cold spots.
Insulation brands we work with
- Knauf Insulation (Earthwool, Supafil blown)
- Rockwool
- Superglass
- Isover
- Kingspan
- Celotex
- Recticel
- Xtratherm
- Steico wood-fibre
- YBS and Actis multifoil
The exact system and brand for your home are confirmed in your written quote.
Heat, bills and EPC
What it does for your heat loss, bills and EPC
An empty cavity lets heat pass straight through the wall. Filling it lowers the wall's U-value considerably, so rooms hold their heat for longer and the heating runs less — often one of the best-value measures on an EPC for homes with unfilled cavities. Solid walls lose even more heat; lining them inside gives a similar improvement, room by room.
See the EPC points and savings for your home in the EPC plannerU-value before and after, typical heat and bill saving, and EPC points — worked out for your property.Price
How much does bay, dormer and reveal insulation cost?
Priced after survey
Jobs like this vary too much for a fair online price, so we measure first and give you a fixed written quote — with no obligation.0% VAT on energy-saving materials
Insulation, solar panels, batteries and heat pumps installed in homes in Great Britain are zero-rated for VAT until 31 March 2027. Windows and doors are not included.What to expect
Time on site, disruption and approvals
Time on site
Often a day or two, ideally alongside new windows.
Disruption
Cavity work is done from outside through small drilled holes, which are filled and colour-matched afterwards. Internal wall insulation means clearing the rooms being done.
Planning and building control
Cavity wall insulation must comply with Building Regulations and is certified through a competent person scheme or building control. Internal wall insulation doesn't need planning, but listed buildings need consent.
Guarantee and standard
Manufacturer's guarantee, confirmed in your quote.
60-second grant check
Could a grant help pay for it?
Grant eligibility checker
About 60 seconds · plain results: likely, possibly or not eligible
Before we start
What type of property is it?
Questions
Bay, dormer and reveal insulation: your questions answered
Why are bay windows so cold?
Bays usually have thin walls, roofs and floors with little or no insulation, plus a lot of glass. Insulating the bay roof, walls and seat area removes a common cold spot.
What are window reveals and why insulate them?
The sides, head and sill of a window opening. When walls are insulated, uninsulated reveals become cold bridges where condensation and mould can start.
Is it best done with new windows?
Yes — replacing windows is the ideal time to insulate reveals and dormer cheeks, which is why we often do both together with LINX Glass.
Group B
More in cavity and internal walls
Cavity wall insulation
A borescope survey, then blown mineral wool or bonded bead injected into empty cavity walls.
Cavity wall extraction and refill
Failed, wet or slumped cavity insulation removed, wall ties checked, then refilled.
Cavity wall tie replacement
Replacing corroded wall ties, often found during cavity extraction.
Cavity survey only
Borescope and thermal imaging to show whether a wall is empty, part-filled or failed.
Party wall cavity insulation
Filling cavity party walls to stop hidden 'party wall bypass' heat loss.
Narrow and hard-to-treat cavities
Specialist bead or wool systems for narrow, stone-faced, exposed or high-rise cavities.
Begin your project
Ready to talk about bay, dormer and reveal insulation?
Tell us about your home and we'll arrange a survey, then a fixed written quote — no obligation.