Roof Ventilation Requirements Uk

Eaves soffits and fascias.

Roof ventilation requirements uk.

To meet the requirements set out by the government for thermal insulation roof ventilation may be a requirement in order to achieve the desired certification for the property. Swish ventilators for roof voids are covered by british board of agrément certificate no 91 2620. When used in accordance with the certificate swish ventilators will satisfy the following statutory requirements. Ventilation openings shall have a least dimension of 1 16 inch 1 6 mm minimum and 1 4 inch 6 4 mm maximum.

For example in the average house with a cold loft there should be a minimum of a 7mm continuous ventilation gap at eaves when using a vapour permeable underlay with a normal unsealed ceiling. A cold roof is a traditional loft space as seen in the vast majority of uk homes and other parts of the world. The types of ventilation covered includes mechanical passive stack background and purge rapid. To provide ventilation opening points can usually be provided on the following areas of a pitched roof.

This specifically relates to cold flat roofs which require ventilation because they are more susceptible to high levels of condensation developing on the decks and external tiling or cladding. A minimum 50mm free air path should be maintained between the top of the insulation and the underside of the roof decking. If ridge or eaves ventilation is not possible ventilation tiles can be used at high or low level to achieve the required airflow. The minimum requirements for cold roof ventilation are set out in bs 5250 control of condensation in buildings which takes into consideration span pitch and roof area.

Slating and tiling for pitched roofs and vertical cladding code of practice recommends that roof ventilation be provided in accordance with bs 5250. Enclosed attics and enclosed rafter spaces formed where ceilings are applied directly to the underside of roof rafters shall have cross ventilation for each separate space by ventilating openings protected against the entrance of rain or snow. This page deals with roof ventilation and roof ventilation problems or the fitting of roof ventilation to existing cold roofs. Bs 5250 sets out the minimum requirements for roof space ventilation.

25mm at eaves on each slope and 5mm at ridge. Warm roof ventilation specification for a simple duo pitch roof bs 5250 specifies sufficient ventilation as being. The wider the span the more free airflow is required in the roof space.