Solid Wall Insulation Glasgow: Internal vs External, Costs & Grants 2026

Most Glasgow tenements and Victorian homes have solid sandstone walls without cavities. Solid wall insulation can cut heating bills by 35%, but internal vs external makes a big difference.

Does your Glasgow home have solid walls?

Check if your property needs solid wall insulation rather than cavity wall insulation:

Properties with solid walls

• Victorian tenements (most built 1850-1920 with sandstone solid walls)
• Pre-1920s villas and townhouses in West End, Pollokshields, Dennistoun
• Listed buildings (category A, B, or C)
• Properties in conservation areas built before 1920

How to check: Measure your external wall at a door or window. If it's more than 260mm (around 10 inches), you likely have solid walls. Alternatively, look at the brick pattern. Solid walls show headers (short brick ends) in the pattern, while cavity walls show only stretchers (long brick sides).

Internal vs external solid wall insulation

Internal wall insulation (IWI)

How it works: Insulation boards (typically 80-120mm thick) are fixed to internal walls and covered with plasterboard.

Pros:

• Cheaper: £8,000-11,000 for typical Glasgow tenement flat
• No scaffolding required
• No planning permission needed (even in conservation areas)
• Can be done room-by-room over time
• Doesn't change building exterior

Cons:

• Reduces room size by 100-150mm per wall
• Disruptive (rooms must be emptied, replastering, redecoration)
• Skirting boards, electrical sockets, radiators need moving
• Doesn't treat thermal bridging at party walls or floors

External wall insulation (EWI)

How it works: Insulation boards (typically 100-150mm) are fixed to outside walls and covered with render or cladding.

Pros:

• No room size loss
• Treats thermal bridging (wraps whole building envelope)
• Protects sandstone from weathering
• Improves appearance of roughcast tenements
• Can be done without moving out

Cons:

• More expensive: £10,000-16,000 for whole building
• Requires scaffolding (adds £2,000-4,000)
• Planning permission required in conservation areas
• Changes building appearance
• Usually needs whole tenement to agree (if shared ownership)

Costs for solid wall insulation in Glasgow

Internal insulation (2-bed tenement flat)

£8,000-11,000 - insulating external walls only

Internal insulation (3-bed terraced house)

£9,000-13,000 - larger wall area

External insulation (whole tenement building)

£80,000-150,000 - cost shared between flats (£10,000-20,000 per flat)

External insulation (detached house)

£12,000-16,000 including scaffolding

Annual heating savings

£300-450/year (Energy Saving Trust Scotland, 2026)

Payback period

18-30 years at full cost, 8-15 years with grants

Scottish grants for solid wall insulation

Home Energy Scotland Grant and Loan

All Glasgow homeowners can access:

• Up to £7,500 grant (no repayment)
• Up to £7,500 interest-free loan (repay over 10 years)
• Total funding: up to £15,000

Solid wall insulation qualifies as part of an energy efficiency package. You'll need a home energy assessment first (free through Home Energy Scotland).

Warmer Homes Scotland

Low-income households receiving benefits can get solid wall insulation completely free through Warmer Homes Scotland. Eligibility based on Universal Credit, Pension Credit, or other qualifying benefits. See full eligibility guide.

Glasgow City Council area schemes

Some Glasgow neighbourhoods have targeted external wall insulation programmes funded by Scottish Government. These schemes cover whole streets and may be free or heavily subsidised. Check glasgow.gov.uk or call Home Energy Scotland (0808 808 2282) to see if your postcode qualifies.

Solid wall insulation in conservation areas

Glasgow has 24 conservation areas where special rules apply. If your property is in a conservation area:

Internal wall insulation

• No planning permission required (internal changes don't need consent)
• Suitable for listed buildings
• Must use breathable materials in historic buildings

External wall insulation

• Planning permission usually required for front-facing walls
• Often refused on listed buildings (category A or B)
• May be approved for rear elevations (not visible from street)
• Check with Glasgow City Council before getting quotes

Best insulation materials for Glasgow sandstone

Glasgow's sandstone walls need breathable insulation that allows moisture to escape:

For internal wall insulation

• Wood fibre boards (breathable, good for historic buildings)
• Phenolic foam boards (thinner profile, good for small rooms)
• PIR boards with vapour control layer (best thermal performance)

For external wall insulation

• Mineral wool (breathable, good for exposed locations)
• EPS boards (expanded polystyrene, cheaper, widely used)
• Phenolic boards (thinner profile for conservation areas)

Avoid: Impermeable materials that trap moisture against sandstone (can cause damp and stone decay over time).

Is solid wall insulation worth it in Glasgow?

Solid wall insulation has a longer payback than cavity wall insulation but delivers bigger savings:

• Heat loss reduction: 35-45% reduction through walls
• Annual savings: £300-450 on heating bills
• Comfort improvement: eliminates cold walls, reduces condensation
• Carbon reduction: 1.5-2 tonnes CO₂ per year

With grants, payback drops to 8-15 years. For homeowners planning to stay long-term, solid wall insulation is usually worth it, especially combined with other improvements like double glazing and loft insulation.

Common questions

How much does solid wall insulation cost in Glasgow?

Solid wall insulation costs in Glasgow range from £8,000-11,000 for internal wall insulation (IWI) and £10,000-16,000 for external wall insulation (EWI) on a typical tenement flat or terraced house. Costs depend on wall area, access, and whether you're in a conservation area. Most Glasgow homeowners can access grants up to £7,500 through Home Energy Scotland.

Should I choose internal or external wall insulation?

Internal wall insulation is usually better for Glasgow tenement flats (cheaper, no scaffolding, no planning issues) but reduces room size by 100-150mm. External wall insulation is better for detached houses (no room loss, treats thermal bridging) but costs more and may require planning permission in conservation areas.

Can I insulate a listed building in Glasgow?

Yes. Internal wall insulation is usually acceptable for listed buildings as it doesn't change external appearance. External wall insulation is typically refused on category A and B listed buildings. Always get listed building consent from Glasgow City Council before starting work.

How long does solid wall insulation take?

Internal insulation takes 2-4 weeks for a typical flat (room-by-room approach possible). External insulation takes 4-8 weeks for a whole tenement building depending on scaffolding, weather, and access.