Insulation prices in the UK vary depending on the type of insulation, the size of your home, access, and whether any prep work is needed. This guide breaks down the most common insulation types, typical cost ranges, and what can push quotes up or down.

Average insulation costs by type

Below are typical “ballpark” ranges to help you plan. Real quotes depend on your property, region, and installer.

Insulation type	Typical cost range	Best for	Main price drivers
Loft insulation	£300–£1,500	Most homes with accessible loft space	Loft size, existing insulation, boarding, access/hatch
Cavity wall insulation	£700–£2,500	Homes with suitable cavity walls	Wall area, cavity condition, scaffold/height, material used
Solid wall (internal)	£4,000–£12,000+	Older homes without cavities	Room count, finishing/plastering, sockets/radiators moved
Solid wall (external)	£8,000–£25,000+	Homes needing major fabric upgrade	Scaffold, render/finish choice, detailing around windows/doors
Underfloor insulation	£1,200–£4,000+	Suspended timber floors	Access from below, lifting floors, area covered
Draught-proofing	£100–£600	Almost all homes	Doors/windows condition, chimney balloon, gaps/seals

What affects insulation quotes the most?

1) Your home size (area, wall height, loft depth)

More area usually means more materials and labour. Higher walls can also increase scaffold and access costs.

2) Access and prep work

Clear access can lower costs. Extra work like moving loft boarding, clearing stored items, fixing damp issues, or repairing wall defects can add to the quote.

3) Existing insulation and condition

If insulation is already present but uneven, compressed, or damp, installers may recommend topping up or removing and replacing it.

4) Property type and age

Older homes often need different approaches (for example solid wall insulation) and more care around ventilation and moisture management.

Which insulation gives the best value?

Solid wall insulation can be transformative for comfort, but it’s usually a bigger investment. Many homeowners start with loft + draught-proofing, then move onto walls/floors if needed.

Loft insulation costs

Loft insulation price depends on loft area, ease of access, and whether you’re topping up existing insulation or starting from scratch.

• Topping up is usually cheaper than a full replacement.
• Boarding the loft for storage adds cost (materials + labour).
• Hatch/ladder upgrades can be added if access is poor.

Cavity wall insulation costs

Cavity wall insulation is only suitable if your wall construction and cavity condition are right. Installers typically assess wall type, exposure, and any signs of damp risk before proceeding.

Solid wall insulation costs (internal vs external)

Solid wall insulation costs more because it involves major work. You’ll usually choose between:

• Internal wall insulation: reduces room size slightly, may involve moving sockets/radiators.
• External wall insulation: changes the outside finish, often needs scaffold, can improve weatherproofing.

Can I get insulation for free?

Some households can access free or discounted insulation through government-backed schemes delivered by energy suppliers or local authorities. Eligibility often depends on household circumstances and property efficiency.

How to get the best price (without compromising quality)

1. Get at least 3 quotes for the same measure and scope.
2. Check what’s included (prep work, waste removal, making good, guarantees).
3. Ask about ventilation (especially for older homes) to reduce condensation risk.
4. Start with the cheapest wins (draught-proofing + loft) before major wall work.

How to avoid insulation scams

• Be wary of cold calls offering “guaranteed free insulation”.
• Only use installers who provide written quotes and clear guarantees.
• Don’t pay large deposits without a contract and terms you understand.