Roof Void Ventilation

In cold climates snow can enter the soffit and ridge vents melt and potentially cause rot.

Roof void ventilation.

Roof voids must be ventilated in order to stop warm air condensing on cold surfaces. The outside air that s taken in disperses through higher parts of the roof. Duo pitch roofs greater than 200 pitch or greater than 10m span should have additional ventilation at the ridge to assist airflow through the roof void equivalent to at least a 3 mm wide continuous gap. Ventilation can be accomplished using various products and techniques.

To be sure your roof is getting enough ventilation there are simple calculations that you can follow. A roofing ventilation system works by pulling in air from intake vents that are placed on the lower part of the roof. Before we explore how to ventilate an attic space it is prudent to understand how much ventilation is needed. Airtrak assists specifiers builders and specialist contractors in helping them to meet the requirements of the building regulations in relation to the important issue of roof void ventilation and the control of condensation.

What is less straightforward is the ventilation of the roof void above. The air gap dimensions shown on the drawings are the minimum widths required for clear continuous ventilation air paths at the eaves. Water vapour can pass through most building materials and will permeate the roof space through plasterboard ceilings service holes downlight fittings and loft hatches etc. Most building codes require a ratio of 1 150 ventilation space to attic floor space.

Beyond the decreased capacity for insulation when venting the roof deck venting the roof deck or the attic has some other drawbacks worth considering. Condensation encourages rot and mould growth.