How to Keep Your Conservatory Warm in Winter

Why Conservatories Are So Cold in Winter

A standard polycarbonate conservatory roof has a U-value of around 1.8 W/m²K — meaning it loses heat almost as quickly as you can generate it. For context, a well-insulated house wall might have a U-value of 0.3 W/m²K or lower. Heat pours out through the roof constantly, and no combination of space heaters and radiators can compensate efficiently. You end up spending a fortune on heating a room that's still too cold to use.

Glass roofs improve on polycarbonate but still typically achieve only around 1.0–1.2 W/m²K in double-glazed form. Even the best triple-glazed glass roof won't come close to the performance of a properly insulated solid roof.

Quick Fixes: What Helps Temporarily

If you're looking for ways to make an existing conservatory more bearable this winter, these can help at the margins:

• Thermal blinds — honeycomb-style blinds trap a layer of air between the blind and the glazing, reducing heat loss slightly; effective for glass walls but have limited impact on the volume of heat lost through the roof
• Draft proofing — seal gaps around doors, between the conservatory and the main house wall, and around older door and window frames; often low-cost and worthwhile regardless
• Electric infrared heaters — these heat people and objects directly rather than trying to warm the air, making a cold conservatory bearable for short periods; running costs are high if used frequently
• Electric underfloor heating — more expensive to install but comfortable and efficient for smaller conservatories; still loses much of its output through the roof if it isn't insulated
• Heavy curtain between house and conservatory — prevents cold from the conservatory affecting the rest of the house, but doesn't make the conservatory itself usable

The Permanent Fix: Replacing the Roof

For a poorly performing sheet roof, replacing it with a specified insulated tiled system can substantially reduce heat transfer. The 0.15 W/m²K figure applies to the specified installed roof build-up, not to the tile alone, and whole-room comfort also depends on glazing, ventilation and heating.

• Far better thermal performance — heat generated by your existing radiators or underfloor heating stays in the room rather than disappearing through the ceiling
• No cold spots — multi-layer insulation eliminates thermal bridging, the cold patches that form around structural elements in poorly insulated roofs
• Meaningfully lower heating costs — because the room holds heat efficiently, a much smaller heat source is needed to maintain a comfortable temperature
• Your existing heating is suddenly sufficient — in most cases, you do not need to install any additional heating; the same radiator or underfloor heating that was struggling before becomes more than adequate

Does It Make a Noticeable Difference?

Replacing a poorly performing roof with a correctly specified insulated build-up can reduce heat loss through the conservatory roof. The improvement depends on the existing glazing, ventilation, heating and how the room is used, so the proposed build-up should be assessed for the individual conservatory.

What About Condensation?

Condensation is common when warm, moisture-laden air reaches cold roof or glazing surfaces. An insulated roof build-up can reduce cold surfaces and condensation risk, but ventilation, heating, glazing and moisture sources still matter; no roof should be presented as a universal cure without assessing the room.

Will I Need New Radiators or Heating?

Heating needs depend on the conservatory size, glazing, insulation, exposure and intended use. A survey can establish the proposed roof build-up, but any heating change should be sized for the room rather than relying on a blanket radiator recommendation.

What Will It Cost?

A tiled roof replacement starts from £1,495. The final price depends on the survey, the conservatory and the agreed specification. See our full cost guide or request a free quote for an accurate figure based on your specific conservatory.