Roof Void Ventilation

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.

Roof void ventilation.

To be sure your roof is getting enough ventilation there are simple calculations that you can follow. The air gap dimensions shown on the drawings are the minimum widths required for clear continuous ventilation air paths at the eaves. In cold climates snow can enter the soffit and ridge vents melt and potentially cause rot. The outside air that s taken in disperses through higher parts of the roof.

Condensation encourages rot and mould growth. Beyond the decreased capacity for insulation when venting the roof deck venting the roof deck or the attic has some other drawbacks worth considering. 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. Inadequate venting causes moisture and heat to get trapped in your attic.

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. Roof voids must be ventilated in order to stop warm air condensing on cold surfaces. Ventilation of attic spaces is required by most building codes as well as by roofing material manufacturers and the national roofing contractors association nrca. Ventilation can be accomplished using various products and techniques.

What is less straightforward is the ventilation of the roof void above. Before we explore how to ventilate an attic space it is prudent to understand how much ventilation is needed.