Introducing or upgrading the ventilation of an existing roof is commonly an obligatory undertaking when the thermal insulation within the roof space is increased. To provide air entry and exit opportunities, ventilation apertures are introduced through the soffit on opposing sides of the property. Once established, air can flow into and out of the roof space (as long as the insulation laid within it is restrained from blocking the flow route where the converging roof timbers approach plate level).

After the soffit apertures have been drilled to provide 70mm holes, the installer may choose whether the Type CSV Circular Soffit Ventilators are fitted in a ‘see’ or ‘no see’ manner.

Type CSV ventilators have a deflecting louvred face, providing positive air entry and insect screening. Unlike standard grille ventilators, rotating the Type CSV so the louvres slope downwards towards the property masonry face results in the ventilation openings being almost hidden from view, when viewed from the ground. The soffit can maintain a continuous unbroken appearance.

Alternatively, fitted with the louvres facing the opposite direction – outwardly – provides a punctuated soffit appearance. The installer has a choice. The Type CSV is available in various colours and has one of the highest airflow ratings of 2,100mm², which means fewer need be installed to provide the required performance level.

Within the roof space the airflow path can be maintained by placement of Type REV Refurbishment Eaves Ventilators. When pushed into position the ventilator top flaps fold over to follow the roof line. The moulded flap shape maintains a void between it and the sloping roof via which air can flow unhindered. The roof insulation is then laid into the folded section.

Together the Type CSV + REV offer a rarely seen advantage when ventilating an existing roof.

Soffit ventilators...to see or not to see

Soffit boards - news from other companies

Soffit boards - companies

Sign up to receive the free BUILDING DESIGN bulletin