What Is External Wall Insulation
External Wall Insulation (EWI) is a system used to improve the thermal efficiency of buildings by adding insulation boards, mesh, primer, and render to the outer walls.
In cities like London and Wembley, where many properties were built before modern insulation standards, EWI is one of the most effective ways to save energy and protect walls from moisture.
👉 Visit our External Wall Insulation category to see adhesives, insulation boards, mesh, and renders from trusted brands Lakma and Tytan.
Why London Homes Benefit From External Wall Insulation
Thousands of London homes built before the 1980s lose a significant amount of heat through solid brick walls. Applying an EWI system can reduce heat loss by up to 45% and lower annual energy bills by £500–£800.
Key benefits of EWI for London properties:
- Improved energy efficiency and lower heating bills
- Reduced condensation and damp
- Enhanced appearance with new render finish
- Increased property value and EPC rating
Related reading:
- EWI vs Internal Wall Insulation – Which Is Better for UK Homes?
- Best Adhesives for EWI Installation in 2025
External Wall Insulation Costs in 2025
The average cost of external wall insulation in London ranges between £95 and £130 per m². Prices depend on insulation type, render finish, and wall condition.
| Property Type | Typical Wall Area | Estimated Total Cost | Installation Time |
|---|---|---|---|
| Small Terraced House | 80–100 m² | £8,000 – £11,000 | 5–7 days |
| Semi-Detached House | 120–160 m² | £12,000 – £18,000 | 7–10 days |
| Detached House | 180–220 m² | £17,000 – £25,000 | 10–14 days |
Want to know your exact project cost? Try our free External Wall Insulation Calculator.
The Best EWI Materials for the UK Climate
When choosing materials, focus on quality and system compatibility.
Below are the main components of a durable EWI setup:
1. Insulation boards:
Graphite EPS – excellent for energy savings.
2. Adhesive and basecoat:
Choose high-strength, flexible adhesive.
👉 Recommended: Tytan EWI Adhesive
3. Reinforcing mesh:
Provides structural stability and prevents cracking.
👉 Recommended: Penguin BM fibreglass mesh 160 g/m²
4. Render finish:
Silicone or silicate render ensures durability and UV resistance.
All materials can be ordered directly from Penguin BM, with fast delivery across the UK.
Example EWI System Setup for UK Homes
As a specialist supplier of external wall insulation materials, Penguin BM provides complete EWI systems designed for the UK climate. Below is an example setup commonly used by contractors and installers across London and the South of England.
| System Component | Recommended Product | Purpose |
|---|---|---|
| Insulation Board | Graphite EPS 100 mm or Mineral Wool | Provides thermal protection and sound insulation |
| Adhesive and Basecoat | Tytan EWI Adhesive | Bonds insulation boards to walls and forms the base reinforcement layer |
| Reinforcing Mesh | Lakma Fiberglass Mesh 160 g/m² | Strengthens the surface and prevents cracking |
| Primer | Lakma Totalgrunt Primer 12kg | Improves adhesion between the basecoat and the final render layer |
| Render Finish | Lakma Silicone Render (1.5 mm grain) | Decorative, breathable, and weather-resistant top layer |
EWI Funding and Grants in the UK
Several schemes support energy-efficient home upgrades in 2025, including external wall insulation.
Homeowners may qualify under:
- ECO4 – Energy Company Obligation program
- Local council initiatives in London boroughs
🔗 More details: UK EWI Grants 2025
Why Choose Penguin BM
Penguin BM is a trusted EWI materials supplier based in London, Wembley.
We provide full systems and technical support for installers and contractors.
Our advantages:
- Official distributor of Lakma and Tytan systems
- Trade pricing and fast delivery
- Technical advice for installation projects
- Local support and collection point in Wembley
📍 Address: 416 Ealing Rd, London, Wembley HA0 1JQ
📞 Phone: +44 075 1528 3453
✉️ Email: info@penguinbm.com
Calculator FAQs
How accurate is the External Wall Insulation Calculator UK?
Our External Wall Insulation Calculator UK is based on real UK coverage rates for insulation boards, adhesives, mesh and renders. Results are highly accurate for most projects, but we recommend adding a 5-10% waste factor.
What type of render is best for external wall insulation?
Silicone renders are the most popular in the UK due to their flexibility and water resistance. Compare options in our render guide.
How do I select the right adhesive?
It depends on your insulation boards and project conditions. Our guide on selecting the right adhesive explains when to use cement-based vs. foam adhesive.
Ready to Order EWI Materials?
Explore our full range of external wall insulation systems from Lakma and Tytan or get a free project estimate with our EWI Calculator.