It depends on insulation position, underlay vapour resistance, ceiling airtightness and roof geometry. Follow the condensation-risk design and current regulations.
Airflow Components for Condensation Control in Roof Spaces
Warm, moisture-laden air can condense when it reaches colder parts of a roof. MacBlair stocks ventilation components for eaves, ridges and roof slopes, allowing airflow to be built into the condensation-control strategy.
Vent position and free area must follow the roof design. A cold roof often needs a clear path from low-level inlets to high-level outlets, while a warm roof and vapour-open underlay can use a different detail. Do not mix rules from unrelated constructions.
Keep loft insulation from blocking eaves vents, and match any roof membrane to the ventilation strategy. High-level components may integrate with dry ridge systems, while tile vents must fit the selected roof covering. Extractor ducts should discharge outside, not into the loft.
Roof Ventilation FAQ's
Low-level and high-level vents are positioned to move air through the required void. Complex roofs may need extra vents around hips, valleys or interruptions.
Yes. Use trays or barriers to keep the designed air path open at the eaves while maintaining insulation coverage.
Ventilation is one part of control. Indoor moisture, air leakage, insulation gaps and blocked ducts must also be addressed.
No. Moist air should travel through a sealed, insulated duct to an external terminal, following the fan and Building Regulations guidance.