How To Vent A Warm Flat Roof

The fascia wood is screwed directly onto the end of the roof joists and there are no soffits to put a vent into.

How to vent a warm flat roof.

A warm roof is defined as being when the all or the majority of the insulation is above the joists or deck. That s not to say that roof ventilation is only valuable in the winter. In general the roof structure is better protected from the more extreme scales of hot and cold weather. Roof is flat fibreglass so no over fascia vents like you would do with pitched roof.

In general it is suited to external outbuildings. If you have any questions or need any advice feel free to drop a comment below and he will endeavour to reply. I need to vent the 50mm gap above the ceiling insulation on a cold deck flat roof. The major difference between the warm flat roof and the cold flat roof has to do with the air flow between the roofing timbers known as joists that help to hold up the roof.

He has come across just about every type of flat roof in existence. A warm roof and a cold roof. The lower cost of installing a cold roof is usually one of its main advantages. This video shows the key features of a flat roof cold deck construction and how to draw the details to a scale of 1 10.

On flat roofs with an overhang it is possible to install continuous soffit vents tied into a continuous ventilation baffle between the rafters. Steven has been working on london s flat roofs for over 30 years. I am skeptical that soffit vents on each end of a rafter spacing. However in many situations the insulation may need to be primarily or entirely below the flat roof membrane and between the roof joists if so what are the best options.

In the warm flat roof construction there is insulation packed into every possible space where air can flow. But unlike a more steeply pitched roof there is no low soffit vent and higher ridge vent to set up a convective ventilation current. Unvented flat roofs a technical discussion flat roofs have often been built with the insulation all on top of the vapor closed drainage plane as this avoids dew point condensation issues inboard of the roofing. It will also prevent warm air from drifting into the roof void.

I only know that during the last building regulation inspection. The roof itself is therefore kept warm. They work with multi layer and three layer roofing systems helping to reduce the build up of moisture. In the summer differences between your roof temperature and the outside air can still cause condensation especially interstitial condensation or water trapped in the layers of your roof.

By majority the rule of thumb is that in a domestic house not flats approximately a third of. Vents ensure that a roof will be the same temperature as the air outside of it.