Why is my glass extension so hot?

Why it happens

• A lot of glass in one place. A wall of bi-folds or sliders is often the largest area of glass in the house.
• Glass overhead. Rooflights and lanterns take the sun when it's strongest.
• Orientation. Extensions usually face the garden, and gardens are often south or west facing.
• Hard surfaces. Stone, tile and polished concrete floors absorb heat during the day and release it in the evening.
• Limited ventilation. Large fixed panes and doors that are only opened in good weather leave the heat nowhere to go.

Your options

• Solar control film on the doors, rooflight or both, chosen to suit the glass.
• External shading, such as a canopy, louvres or a pergola, which may need planning permission.
• Blinds, including motorised blinds for rooflights.
• Better ventilation, such as an opening rooflight or trickle vents.
• Replacing the glass with a higher-performance solar control glass, which is effective but costly and disruptive.

If the extension is new

Film can usually go on new glass, but check your glazing warranty first and make sure the film is compatible with the glass. A good installer will check both.