Cavity insulation for new builds and extensions for Harwich properties
If your property is in Harwich or the CO12 district or nearby Clacton-on-Sea and Colchester, it is within our Essex coverage. It is around 37 miles north-east of Chelmsford.
Harwich properties with rendered or painted walls get a closer look at the outer finish, because cracked render can let rain behind it. If a wall in Harwich is not suitable, for example because of an undiagnosed damp patch or a very exposed gable, you are told so in writing with the reason.
Every elevation is judged on its own exposure. Much of Essex sits in the more sheltered driving-rain zones of the UK, which widens the choice of fill. Exposed elevations, coastal sites and high ground still get checked wall by wall.
In terms of approvals, in Harwich filling a cavity is notifiable building work and needs a building notice or competent-person self-certification.
Funding in England
In England, ECO4 runs to 31 December 2026 and Warm Homes: Local Grant supports low-income households through councils.
Sources: GOV.UK: extending the ECO4 end date, government response; GOV.UK: Warm Homes Plan.
What we work from
Your architect's or designer's specification and the energy calculation for the job. We match the product, thickness and fixing to that spec, keep cavities clean as the walls rise, and fit cavity trays, closers and stop ends where shown so the building control inspection goes smoothly.
What is included in Harwich
- Trays, closers and stop ends as drawn
- Clean-cavity working
- Batts or boards to the specified U-value
- Photo record for building control
Guide prices for Harwich
| Cavity insulation for new builds and extensions guide prices | Guide price |
|---|---|
| Full-fill batts supplied and fitted, per m² | £9–£16 |
| Partial-fill boards supplied and fitted, per m² | £14–£26 |
Prices are shown before any VAT; the VAT treatment for new-build work is confirmed on your quote. Guide ranges only: the fixed price is confirmed in writing before any work starts, and anything that could not be seen at survey is agreed with you first.
What happens next for a Harwich property:
Get in touch
Online, by phone or WhatsApp, whichever suits you.
Survey visit
The surveyor checks each wall and looks into the cavity where needed.
Your result in writing
What we found, what it means, and a fixed price if work is needed.
Booked work
Carried out by the installer named on your quote, with their scheme registrations.