How to Insulate a Conservatory: Roof, Walls and Floors (Materials Guide)
Conservatories lose heat through the roof, walls and floor, which is why many feel freezing in winter and too hot in summer. This guide covers materials Insulation Warehouse Direct sells that people use when upgrading a conservatory — especially the roof — without claiming we install or that every conservatory can hit new-build Part L figures.
Quick answer
Most DIY and trade upgrades focus on the roof: rigid PIR boards, multifoil such as SuperFOIL SF19+, or a combination with a plasterboard or insulated-plasterboard ceiling, plus sealing gaps. Walls and floors can take insulated plasterboard or floor PIR where the detail allows. Always check structural load, condensation risk and planning/Building Control before you change a glazed roof. We supply materials only.
Roof options (materials view)
- PIR between or under rafters / roof structure: foil-faced boards from Celotex, Kingspan or Recticel. Thickness depends on the depth available and the U-value you are aiming for — use the PIR U-value calculator.
- Multifoil: SuperFOIL SF19+ is often chosen where depth is limited; follow the manufacturer’s air-gap and taping rules. See our SuperFOIL SF19+ guide.
- Ceiling finish: standard or insulated plasterboard on a suitable frame, with vapour control as specified.
Walls and floors
Solid dwarf walls can take internal lining with insulated plasterboard (fitting insulated plasterboard). Floors over concrete may take PIR under a screed or floating finish — see flooring insulation boards. Glazed walls are a different problem (glass performance, secondary glazing, blinds) and sit outside our range.
Moisture and overheating
Adding insulation without thinking about ventilation and solar gain can shift where condensation forms or make summer heat worse. Keep designed vents clear, follow VCL guidance, and read our moisture control guide. For dark conservatory roofs, shading and ventilation matter as much as insulation thickness.
Buying checklist
- Measure available depth in the roof and walls.
- Decide PIR, multifoil, or both as per your designer’s detail.
- Add foil tape for PIR joints (membrane tapes / Alpha foil tape on site).
- Order boards, membranes and plasterboard together to cut delivery cost.
Frequently asked questions
Can insulating a conservatory roof bring it into the heated house for Building Regulations?
That depends on how it is connected and what Building Control require. Ask them before you treat it as a heated extension.
Do you sell ready-made conservatory roof panels?
We sell PIR, multifoil and drylining materials — check product pages for what is in stock rather than assuming a proprietary roof cassette.
Do you install insulation, do surveys or help with grants?
No. Insulation Warehouse Direct sells insulation materials online. We do not install insulation, carry out surveys or handle grant applications. If you want it fitted, use a qualified installer, and for grants check the official GOV.UK energy schemes. We are happy to supply the materials your installer specifies.
Will multifoil alone stop summer overheating?
Insulation slows heat flow; shading and ventilation are still needed. Follow SuperFOIL’s published guidance for air gaps.
| Where | What we deliver | Delivery charge |
|---|---|---|
| England | All ranges | Free on insulation, plasterboard and drylining from £400 ex VAT. Celotex: £400 ex VAT minimum, free delivery. Access panels: £15 + VAT under £300 ex VAT, free from £300 |
| Mainland Wales and mainland Scotland | British Gypsum (including Gypframe), Celotex, Knauf and access panels | £400 ex VAT minimum plus £40 + VAT (access panels: £15 + VAT under £300 ex VAT, free from £300) |
| Scottish islands | Not delivered | – |
| Northern Ireland | Not delivered | – |
Browse PIR, SuperFOIL and insulated plasterboard. Company: Bay Drywall and Insulation Supplies Ltd (company no. 14473556), Unit 3 Babbage Court, Totnes Industrial Estate, Totnes, Devon TQ9 5JE.