How Much Ventilation Does A Flat Roof Need

Let owens corning roofing help you calculate exactly how much ventilation you will need for a healthy and balanced attic with our 4 step ventilation calculator.

How much ventilation does a flat roof need.

A cold roof or hot roof. Hot roofs have the roof deck then insulation then the roofing material. Enter square footage calculate or enter the square footage of the attic or area to be vented. Choosing the correct ventilation solution for a flat roof will play an integral role in extending a structure s lifespan.

How much ventilation does a flat roof need. Federal housing authority recommends a minimum of at least 1 square foot of attic ventilation evenly split between intake and exhaust for every 300 square feet of attic floor space. While hardly anybody agrees on the best roof ventilation system everybody agrees some roof vents do hardly any good at all. Proper attic ventilation consists of a balance between air intake at your eaves soffits or fascias and air exhaust at or near your roof ridge.

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. 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. The majority of roofing experts agree that ridge vents are the most effective and cost effective roof vents available. It makes sense as all of us know that the most humid rooms in the house like the bathroom and kitchen need it.

You only need ventilation in a cold roof. All things being equal wind driven turbine vents also known as a whirlybird roof vent do move more air than flat vents but only when the wind blows. However we rarely think like that for roofs even though they undoubtedly require ventilation. No insulation is on top.

Flat roof vents have no moving parts to break or squeak but don t vent as much air as wind driven vents. Many people falsely assume that their roof doesn t require ventilation. I have roof vents so i have roof ventilation. How much ventilation does a flat roof need.

Ventilation is not needed in a warm roof. It s unavoidable that the thermal temperature in the roof space will bear the brunt of the heat generated in the living spaces below. It depends on where the insulation is installed. Any type of roof from tpo to epdm can be either hot or cold.

Take for example ridge vents.