How Much Ventilation Does A Flat Roof Need

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.

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. 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. Take for example ridge vents. I have roof vents so i have roof ventilation.

How much ventilation does a flat roof need. You only need ventilation in a cold 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. Ventilation is not needed in a warm roof.

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. A cold roof is where all of the insulation is placed either between and under or completely under the joists or deck. While hardly anybody agrees on the best roof ventilation system everybody agrees some roof vents do hardly any good at all. A cold roof or hot roof.

The majority of roofing experts agree that ridge vents are the most effective and cost effective roof vents available. Hot roofs have the roof deck then insulation then the roofing material. Many people falsely assume that their roof doesn t require ventilation. Any type of roof from tpo to epdm can be either hot or cold.

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. However we rarely think like that for roofs even though they undoubtedly require ventilation. It depends on where the insulation is installed. No insulation is on top.

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. Enter square footage calculate or enter the square footage of the attic or area to be vented. Flat roof vents have no moving parts to break or squeak but don t vent as much air as wind driven vents. In this way the roof itself is kept cold.

The answer depends on the type of roof you have.