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Heating & Ventilation

Venting the Extension Where it Joins?


There is commonly a requirement to provide roof ventilation when extending a property. Where a flat roof extension is added to an existing building, provision is required at the attachment point (the roof/wall intersection) with corresponding ventilation opposite on the outer edge of the extension.

With an airflow rating of 25,000mm² per running metre, the Roof Abutment Ventilator from Cavity Trays of Yeovil provides a novel way of achieving compliance, and does so in a manner that is compatible with the damp protection measures demanded within the Building Regulations.

A timber upstand is fixed to the existing wall utilising vertical stand-off battens to maintain an airflow path between it and around the decking edge. The Type RAV-FL is secured by opening like a book and fixing via its pre-drilled holes to the top of the timber upstand. The remaining section of the ventilator is then closed so it finishes against the masonry where it also is secured through its pre-drilled holes. The ventilator is now in position and can be overdressed with the protective flashing of the obligatory cavitray at the appropriate stage in the building programme.

Ventilation at the opposite side of the extension can be provided by a choice of ventilators offered by Cavity Trays of Yeovil, pending whether a soffit, fascia or hidden flow path is preferred.

The expanding range of products offered by Cavity Trays to protect the building envelope offer the specifier new efficient construction options that are compatible and performance warranted.