Insulation: What Homeowners Should Know in 2026

A concise guide to insulation types, where to insulate first, common problems, and what to watch out for with spray foam. ## Where to Insulate First Heat loss in a typical uninsulated UK home: - **Roof/loft** — 25% of heat loss. Loft insulation is the single most cost-effective energy upgrade. - **Walls** — 35% of heat loss.

Cavity wall insulation is straightforward; solid wall insulation is more complex and expensive. - **Floors** — 10% of heat loss. Often overlooked but worthwhile during renovation. - **Windows/doors** — 20% of heat loss. Addressed by glazing upgrades. ## Common Insulation Types | Type | Best For | Typical Cost | |---|---|---| | Mineral wool (loft roll) | Loft spaces | £5–10/m² | | Blown fibre | Hard-to-access loft areas | £10–15/m² | | Cavity wall beads/foam | Standard cavity walls | £6–12/m² | | External wall insulation | Solid-wall properties | £80–120/m² | | Internal wall insulation | Where external is not possible | £40–70/m² | | Spray foam (open-cell) | Loft rafters, complex spaces | £20–35/m² | | Spray foam (closed-cell) | Specialist applications | £35–55/m² | ## The Spray Foam Question Spray foam insulation is effective when correctly specified, but it has created significant issues: - Some mortgage lenders refuse to lend on properties with spray foam in the loft - Removal is expensive (£3,000–£8,000+) - It can mask roof defects by preventing visual inspection of timbers - Open-cell spray foam is generally lower risk than closed-cell for loft applications **Always check with your mortgage lender before proceeding with spray foam.

** ## What to Ask an Installer - What U-value will the insulation achieve? - Will ventilation be maintained or improved? - Is a condensation risk assessment included? - What guarantee is offered and by whom? - Will Building Regulations notification be handled? --- ### What to do next If you are weighing up an insulation upgrade, EvoHome Improvements can help you understand the right option for the property, plan the project sensibly and, where appropriate, connect it with suitable independent installers or specialists.

EvoHome does not carry out the works directly. Start here: [/start](/start). You can also read more about how this service works at [/services/insulation-installation](/services/insulation-installation).