How Much Roof Ventilation

Ventilation of attic spaces is required by most building codes as well as by roofing material manufacturers and the national roofing contractors association nrca.

How much roof ventilation.

So i ll start by saying something that might sound controversial but really isn t. Dangers of too much ventilation. The two main dangers associated with too much ventilation involve roof damage and increased utility bills. Attic ventilation works on the principle that heated air naturally rises primarily utilizing two types of vents.

As a certified licensed home inspector it is not correct to say too much ventilation is bad for an attic unless rain moisture is getting in. A wind turbine catches the wind and spins a fan which pulls hot air outside. 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. Then aim for about 1 sq.

With a power switch or a thermostat installation an attic fan can be turned on to let hot air from the attic out. The building code lets you reduce that by half under some conditions but more roof ventilation is usually better. 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. Before we explore how to ventilate an attic space it is prudent to understand how much ventilation is needed.

A vented attic where insulation is placed on an air sealed attic floor is one of the most underappreciated building assemblies that we have in the history of building science. Intake vents located at the lowest part of the roof under the eaves allow cool. Ventilation can be accomplished using various products and techniques. The open area of a vent is sometimes listed on the roof air vent as nfva net free vent area.

In of vent opening per 150 sq. Air vent 1320 cfm weatherwood galvanized steel electric power roof vent. If not measure the size yourself. To keep air flowing your roof needs just the right amount of attic ventilation.

So much information has been devoted to the subject of roof venting that it s easy to become confused and to lose focus. 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.