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Ventilation

Loft ventilation: why your roof needs to breathe

Insulation and ventilation go hand in hand. Get the balance wrong and you risk condensation, damp and mould in the roof.

It sounds counter-intuitive, but a well-insulated loft still needs airflow. Insulation keeps the rooms below warm by keeping the loft space cold — and a cold space needs ventilation to carry away moisture, or that moisture condenses on the timbers and felt.

Keep the eaves clear

Most pitched roofs are designed to draw air in at the eaves (the low edges where the roof meets the walls). If insulation is packed tight into those corners, it blocks the airflow and traps damp air. We always leave a clear ventilation gap at the eaves, using baffles where needed.

Common ventilation mistakes

  • Bathroom or kitchen extractor fans venting into the loft instead of outside
  • Insulation stuffed into the eaves, choking the airflow
  • Airtight upgrades elsewhere in the house pushing more moisture into an unventilated roof
  • Gaps around the loft hatch letting warm, moist air rise into the cold loft

Getting the balance right

The aim is simple: insulate the loft floor well, keep the roof space ventilated, and stop household moisture getting up there in the first place. Done together, you get a warm home and a dry, healthy roof.

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