Warm Roof No Ventilation

Without adequate ventilation moisture rises with the hot air and forms condensation on the inside of the roof deck.

Warm roof no ventilation.

Venting prolongs the life of the roof. There is enough exit ventilation space to match the amount of soffit ventilation inlet. Roofers use a circular saw to cut a long slot along the roof ridge if there isn t one then cover it with a plastic flap as shown or a flexible vinyl matrix. In buildings where there is no roof venting anyway and where ventilation is difficult or impossible to achieve an un vented well insulated hot roof can provide a high r value ceiling and may be the second best alternative to preventing ice dam related leaks in cold climates.

No ventilation is required for these types of roofs. Openings along the sides allow air out of the attic cooling the space and lowering your air conditioning bill. If ridge or eaves ventilation is not possible ventilation tiles can be used at high or low level to achieve the required airflow. 25mm at eaves on each slope and 5mm at ridge.

Consequently the article concludes that the concept of venting a flat roof is no longer safe and instead don t vent the flat roof and install a smart vapor retarder inboard. A warm deck roof is where the insulation is placed on top of the rafters joists and the roof covering is then placed over the insulation. Warm roof ventilation specification for a simple duo pitch roof bs 5250 specifies sufficient ventilation as being. This moisture is released into the air inside the house from bathing cooking plants laundry and other causes.

The article notes that the ventilation cannot overcome the significant humidity drive into the flat roof structure caused by small air leaks. The building envelope is tight enough to prevent warm moist air from escaping from the building interior into the roof assembly. The roof assembly has enough insulation and it is properly installed. An unvented roof assembly is possible only if you keep the roof sheathing warm enough to prevent conditioned air from condensing against it.

When the condensation forms on the roof deck it begins to rot the wood. I am about to turn my garage flat roof into a warm roof i have a seperate thread discussing this task in the roofing section with the primary goal of having no ventilation whatsoever as i will be building a decoupled room inside this sealed garage shell to use as a music recording studio so every single hole becomes a compromise for sound isolation.