Back to basics: Ventilation for Pitched Roofs
Posted on 23rd September 2022
With the 2021 update of BS 5250: Management of moisture in buildings – Code of practice, there has been an increasing awareness of how higher levels of thermal insulation can result in increased levels of condensation in the roof space. It is therefore more important than ever to ensure that there are adequate sources of ventilation in the roof.
Hambleside Danelaw have produced this Back to Basics article in order to detail the types of roof ventilation currently available as well as how they can contribute to preventing condensation forming in the roof.
Now that ridge and hip tiles have to be mechanically fixed, the most common method of introducing ventilation to the roof space is to install a ventilated dry fix ridge and hip system, such as Hambleside Danelaw’s CON6+. These contain a specially designed roll-out component that is installed below the hip and ridge tiles. The CON6+ ridge roll allows for a minimum of 5,000mm² of airflow area per linear metre installed (actual 11,700mm²).
Hambleside Danelaw also manufacture two other ridge and hip kits. The CLAY6+ and the MONO6+:
The CLAY6+ is a dry fix ridge and hip system compatible with all commonly available clay and baby ridge tiles and provides a minimum of 5,000mm² airflow area per linear metre installed (actual 11,700mm²).
The MONO6+ is a dry fix ridge system which can be fitted to all roof pitches (subject to being used in conjunction with ridge tiles suitable for that pitch); and can be used with all commonly available mono ridge tile types. The MONO6+ has a minimum of 5,000mm² airflow area per linear metre installed (actual 5,850mm²)
Tile and Slate Ventilators
Tile and slate ventilators are installed as a direct replacement for the tiles or slates, often blending in with the roof surface to improve the appearance of the roof. There are a wide range and variety of ventilators available from various manufacturers, all compatible with different types of tiles, but all with varying ventilation areas. Tile ventilators are easy to install, and some can be used as terminals for soil pipes and extractor fans as well as ventilation of the roof space.
Most of Hambleside Danelaw’s tile and slate vents can be used with mechanical extraction from bathrooms, and all can be used for soil stack ventilation. Simply attach the flexi-pipe adaptor to the tile or slate vent and connect to the ductwork
The Danelaw product range has a wide range of compatibility, from single and double lap tiles to a range of different slate sizes To learn more about our ventilator compatibility, please refer to Hambleside Danelaw’s compatibility chart, which is available on the Hambleside Danelaw website.
Soffit & Eaves Ventilators
The eaves is the area where the roof meets the exterior wall of the building. It is usually a suitable place to install a form of ventilation, whether through a continuous over fascia, soffit or corbel ventilator strip or individual soffit ventilators that are often fitted retrospectively.
Continuous soffit strip vents are installed onto soffit boards and offer an excellent amount of airflow, with Hambleside Danelaw’s soffit vent providing 10,000mm2 of airflow per metre of vent installed. The fascia board usually carries the eaves gutter and is often used as the primary method of roof space ventilation.
The Importance of Ventilation
Allowing water vapour to exit the roof cavities by providing free flowing ventilation airways can prevent structural damage, decay and the growth of mould caused by moisture and wetness from excessive or repetitive condensation. BS 5250 highlights the importance of managing all sources of moisture in the building, and roofing ventilation is an important part of this strategy.
To learn more about ventilation requirements, take a look at the first Back to Basics article which can be found on the Hambleside Danelaw website.
Share this post: