External wall insulation · Hertfordshire
External wall insulation in Harpenden
If you're planning external wall insulation in Harpenden, start with a free survey: we measure, check the walls and confirm planning and building control for your address. Whole-house jobs and single elevations are both quoted in Harpenden; a cold gable or rear wall can be done on its own where it suits.
- Free survey in AL5 and nearby
- Guide price from £105 per m² + scaffold, 0% VAT
- Fixed written price before work starts
Free survey in Harpenden
Postcode, service and a phone number is all we need.
Part of every quote
- Covers tired brick, pebble dash or failing render with a new finish
- Work happens outside, so you can live at home throughout
- Installing wall insulation in homes is currently zero-rated for VAT until 31 March 2027
- Cills, pipes, vents, meter boxes and the roofline detailed as part of the job
What we look for in Harpenden
Surveys in Harpenden also cover the surrounding AL5 district and towns such as St Albans and Luton. Harpenden sits around 11 miles from Watford. The East of England has a mix of post-war estates, inter-war semis and older solid brick and flint cottages, with some system-built council homes on post-war estates.
Much of Hertfordshire sits in the lower wind-driven rain exposure bands, which keeps the choice of finishes wide — though hilltop, coastal and exposed gable walls can still need a tougher specification, so we check the actual site.
We plan EWI in Harpenden around the details that cause trouble later — cills, eaves, downpipes and the base of the wall above the damp-proof course.
- Postcode district
- AL5
- County or area
- Hertfordshire
- Nation
- England
- Nearby
- St Albans, Luton, Hemel Hempstead, Welwyn Garden City
England: planning and regulations
Planning in Harpenden follows England's national rules: similar-looking finishes on houses are usually permitted, while flats, commercial premises, conservation areas and streets under an Article 4 direction need an application.
Building control applies once more than half of a wall is insulated or re-rendered, or more than a quarter of the whole building envelope, and your written quote says how that's handled.
Which homes is EWI suited to?
EWI is mainly used on solid-walled houses (most homes built before about 1920), on post-war concrete and steel-framed houses, on homes where cavity fill isn't possible, and on bungalows and park homes. It also suits flats and blocks where the whole building is treated at once.
It is less straightforward where the walls face a pavement with no room to project, on listed buildings, or where planning rules want the existing brick or stone left visible. A survey picks these up before you commit.
External wall insulation prices in Harpenden
| Item | Guide price | Notes |
|---|---|---|
| EPS system with silicone render | £105–£145 per m²0% VAT | Most common choice for houses |
| Mineral wool system | £125–£170 per m²0% VAT | Non-combustible, vapour-open |
| Brick-slip finish over insulation | £185–£260 per m²0% VAT | Where a brick look is wanted |
| Three-bed semi, EPS + silicone (incl. scaffold) | £10,200–£17,7000% VAT | 80–100 m² of wall; depends on detailing and access |
Confirmed by a fixed written quote after survey. 0% VAT: installing insulation in a home is zero-rated until 31 March 2027, so these figures are the total; 5% applies from 1 April 2027.
How it works
Tell us about the property
Use the quote tool or form, or call. Photos help.
Free survey
We measure, check the walls and confirm approvals.
Fixed written quote
System, details, access, exclusions and VAT in writing.
Installation
Scheduled for suitable weather, with a clear programme.
External wall insulation in Harpenden: questions
Does EWI need Building Regulations approval?
In England and Wales, usually. Insulating more than half of a wall's area, or more than a quarter of the building's whole external envelope, counts as renovating a thermal element, so building control needs to be involved and the wall should reach about 0.30 W/m²K where that's practical. Scotland and Northern Ireland have their own building standards processes.
Does external wall insulation cause damp?
Not when it is specified and detailed properly. Problems usually come from poor detailing: no starter track above the damp-proof course, gaps at cills and penetrations, or a vapour-closed system on a wall that needs to breathe. The survey checks moisture, ground levels and the wall type before a system is chosen.
Can EWI go over pebble dash?
Usually yes. The dash is tested for adhesion and hollow areas; sound dash can be insulated over with additional mechanical fixings, while loose areas are removed first.
Do you cover Harpenden?
Yes — we survey and quote external wall insulation in Harpenden (AL5) and nearby St Albans, Luton and Hemel Hempstead, with a fixed written price before any work starts.