It depends on room use, airtightness, occupancy and the existing system. Use current Northern Ireland Building Regulations and a ventilation design rather than adding random vents.
Passive Openings for Moisture and Air-Quality Control
Ventilation removes stale, moisture-laden air and provides planned openings for replacement air, cavity drainage and roof-space airflow. MacBlair stocks wall vents, weep vents, roof ventilation products and wall ducts for building and refurbishment work.
Each opening has a different job. Wall vents may provide background or permanent airflow, weep vents drain cavity trays, roof components manage condensation, and ducts carry air between a room appliance and an external terminal. Do not substitute one type for another because the face size appears similar.
Match free area, duct diameter and weather resistance to the design, and keep insulation clear of the airflow path. Coordinate building insulation without blocking openings, connect roof components to roof ventilation systems, and use compatible eaves and soffit details. Combustion air and extract systems need specialist sizing.
Roof Ventilation FAQ's
It can remove moisture, but heating, insulation, air leakage and moisture production also matter. Persistent damp needs its cause identified.
Free area is the effective open area available for airflow after grilles and screens are considered. It is smaller than the face dimensions.
No. Keep the designed route open with sleeves, trays or barriers while maintaining insulation around it.
Yes, moist or stale air should discharge outdoors through compatible ducting and a terminal, not into a loft, cavity or enclosed void.