Retrofit and energy
External wall insulation for social landlords
Insulation boards and render systems on solid-wall and hard-to-treat homes, with detailing done properly.
External wall insulation (EWI) is a system of insulation boards fixed to the outside of a wall and finished with render or cladding. It is one of the main ways to improve solid-wall and non-traditional homes, which are common in social housing stock. Its success depends on detailing at windows, eaves, ground level and services.
How do we approach external wall insulation?
We install EWI systems on houses and low-rise blocks to the system holder's details and your design. On blocks of flats, fire performance of the whole wall build-up is designed and checked before anything is fixed, and the rules tighten with building height.
What is included?
- Survey of walls, services and details before design
- Moving services, downpipes, meters and fittings
- Insulation boards, mesh, base coat and render or brick-slip finishes
- Window reveal, cill, eaves and ground-level detailing
- Fire breaks and non-combustible materials where the design requires them
- Scaffold, protection and resident liaison
- Handover with system guarantee documents
What do we hand over at the end?
- Pre-works survey
- Stage photographs including hidden details
- System guarantee documents
- Funding scheme data where applicable
Who is this service for?
- Retrofit programmes on solid-wall and non-traditional homes
- Landlords tackling cold, damp hard-to-treat homes
- Main contractors on funded projects
Process
How does each job run?
Survey
Walls, services, ground levels and window positions are surveyed. Detailing is agreed before ordering.
Preparation
Services and fittings are moved and the wall is prepared.
Installation
Boards, mesh, base coat and finish are applied to the system holder's details.
Handover
Stage photos, guarantee documents and data your funding scheme requires.
Rules by nation
Which rules shape external wall insulation in each UK nation?
The legal duties sit with the landlord. These are the rules that set the timescales and standards we work to, as checked on 31 October 2026.
Warm Homes: Social Housing Fund Wave 3 (£1.29bn for 2025–2028, plus up to £295m more for 2026/27) requires delivery under PAS 2035/2030, TrustMark-registered installers and, for heat pumps and solar, MCS certification. The fund is closed to new applications. Separately, social rented homes must reach EPC C on one reformed EPC metric by 1 April 2030.
PAS 2035:2023 sets the whole-house retrofit process (assessment, coordination, design, installation and evaluation), and PAS 2030:2023 covers installation. Most government-backed retrofit schemes require both, with TrustMark lodgement. We confirm in writing, before appointment, how each measure in your scope will meet those requirements.
On blocks of flats the fire performance of the whole external wall is a design matter, and the rules on combustible materials tighten with building height. PAS 9980 is the code for fire risk appraisal of external walls of existing blocks. Government policy is for unsafe cladding on buildings of 18 metres and above to be remediated by the end of 2029, and 11–18 metres by the end of 2031.
Decent Homes Standard (England)WHQS 2023 asks Welsh social landlords to set a Target Energy Pathway for their homes by 31 March 2027, informed by a whole stock assessment.
PAS 2035:2023 sets the whole-house retrofit process (assessment, coordination, design, installation and evaluation), and PAS 2030:2023 covers installation. Most government-backed retrofit schemes require both, with TrustMark lodgement. We confirm in writing, before appointment, how each measure in your scope will meet those requirements.
On blocks of flats the fire performance of the whole external wall build-up is designed and checked before work starts, and the rules tighten with building height. We install to the design and do not substitute materials.
WHQS 2023 (Wales)Scottish social landlords work to EESSH2, which is under review. Interim guidance was issued in March 2026, and decisions on a Social Housing Net Zero Standard are expected by spring 2027.
PAS 2035:2023 sets the whole-house retrofit process (assessment, coordination, design, installation and evaluation), and PAS 2030:2023 covers installation. Most government-backed retrofit schemes require both, with TrustMark lodgement. We confirm in writing, before appointment, how each measure in your scope will meet those requirements.
On blocks of flats the fire performance of the whole external wall build-up is designed and checked before work starts, and the rules tighten with building height. We install to the design and do not substitute materials.
SHQS (Scotland)Retrofit funding in Northern Ireland is set by the Department for Communities and the Housing Executive's own programmes.
PAS 2035:2023 sets the whole-house retrofit process (assessment, coordination, design, installation and evaluation), and PAS 2030:2023 covers installation. Most government-backed retrofit schemes require both, with TrustMark lodgement. We confirm in writing, before appointment, how each measure in your scope will meet those requirements.
On blocks of flats the fire performance of the whole external wall build-up is designed and checked before work starts, and the rules tighten with building height. We install to the design and do not substitute materials.
Decent Homes Standard (NI)Guide prices
What does external wall insulation cost?
Rounded planning figures with their sources and VAT basis. Your price depends on the survey, your specification and the region. Use our programme budget tool for a regional estimate.
| Item | Unit | Guide range | Basis |
|---|---|---|---|
| External wall insulation | per house | £10,000–£18,500 | Published figure: FMB (March 2026: average £10,000 for a 3-bed semi); SHDF Wave 1 actual cost £18,395 per install. VAT basis: 0% (energy-saving materials). |
| External wall insulation | per m² | £85–£130 | Published figure: FMB, March 2026. VAT basis: 0% (energy-saving materials). |
Prices checked 31 October 2026. See all guide prices and regional factors.
Questions
External wall insulation: common questions
Can EWI be used on blocks of flats?
Often, yes. On blocks, the fire performance of the whole external wall is a design matter, and the rules on combustible materials depend on the building's height and use. We work to the design and do not substitute materials.
Does EWI cause damp?
Badly detailed EWI can. Most failures happen at window reveals, eaves and ground level, which is where we spend the most care.
Do residents need to move out?
No. EWI is fixed outside, although services and fittings on the wall need to be moved temporarily.
Is EWI eligible for funding?
It is commonly funded through social housing retrofit schemes. Funding conditions usually require PAS 2035 delivery and certified installers, which we confirm for your project in writing.
Related
Which services often go with external wall insulation?
Whole-house retrofit
Fabric-first upgrades planned as a whole: insulation, ventilation, heating and windows in the right order.
Learn more
Loft and cavity wall insulation
Loft top-ups, cavity fill and extraction of failed fill, with ventilation checked alongside.
Learn more
Brickwork, pointing and render repairs
Repointing, brick replacement, render repairs, lintels and cavity tie work on houses and low-rise blocks.
Learn moreFurther reading: Warm Homes: Social Housing Fund and EPC C