A warm flat roof usually does not require ventilation. What space do I need to allow for the ventilation? To ensure sufficient ventilation, enough space must be provided to allow for the movement of air, preventing the risk of condensation forming within the roof.
What is an abutment vent?
The Abutment Ventilation System provides a continuous, unobtrusive, weathertight air path from the roof void to the outside, to comply with the requirements of the Building Regulations. The innovative design enables the system and leadwork to be installed far quicker than traditional methods.
What is a mushroom vent?
Mushroom roof vents – mushrooms are passive, meaning they work without electricity. They are 15” in size. Turbine roof vents – turbines are mushroom-shaped vents that spin with the wind currents and help to expel hot air from your attic. They do not require electricity so they are also passive.
How many vents should my roof have?
The general rule of thumb in these situations is of roughly one vent per every 300 square feet of attic area if the attic has a vapor barrier. If not, there should be one vent for every 150 square feet. You will need to have 1 square foot of vent area for every 150 square feet of attic space.
Do I need upstands for my flat roof?
The requirement for flat roof upstands is set out in the latest revision to the British Standard: BS 6229:2018 Flat roofs with continuously supported flexible waterproof coverings (Section 4.5). The code requires that: “At all abutments the waterproof layer should be turned up to a level not less than 150mm above the adjacent finished roof system.
How does ventilation work on a flat roof?
The installation of sufficient ventilation into a flat roof will ensure warmer air can rise from the living areas and find a way to escape outside without compromising the integrity of the structure. In turn, this will keep the roof’s temperature at a similar level to the level outside.
How much ventilation gap do I need for my flat roof?
Building regulations state that a ventilation gap of at least 50mm must be in place between the insulation and the underside of the flat roof deck. For both a warm and cold flat roof, a vapour control layer must be installed.
How do you install a vapour layer on a flat roof?
On a warm flat roof, the layer is installed underneath the insulation to stop moisture interacting with it through rising thermal pressure lower down in the building. For cold flat roofs, the vapour layer needs to be positioned underneath the insulation layer, on top of the room below to create an effective barrier.
