How Much Ventilation Does A Roof Need

Hot roofs have the roof deck then insulation then the roofing material.

How much ventilation does a roof need.

The majority of roofing experts agree that ridge vents are the most effective and cost effective roof vents available. So much information has been devoted to the subject of roof venting that it s easy to become confused and to lose focus. It depends on where the insulation is installed. Enter square footage calculate or enter the square footage of the attic or area to be vented.

All you need to know about attic ventilation understand the pieces and parts that contribute to quality attic ventilation so that you can better cool down the space and prevent roof damage all. I have roof vents so i have roof ventilation. Hvi recommends vent selection and placement such that 60 percent of the vent net free area is provided by intake vents placed at the under eave area and 40 percent of the vent net free area is provided by exhaust vents on the roof at the ridge or high in the gable area. Ventilation can be accomplished using various products and techniques.

Before we explore how to ventilate an attic space it is prudent to understand how much ventilation is needed. Calculate 20 per cent more for 7 12 to 10 12 pitches and 30 per cent more for a pitch that is 11 12 or greater. 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. A cold roof or hot 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. If the slope of your roof is greater than 6 12 you will need more ventilation to reflect the extra volume of attic space. Many people falsely assume that their roof doesn t require ventilation. How much ventilation does a flat roof need.

Ventilation of attic spaces is required by most building codes as well as by roofing material manufacturers and the national roofing contractors association nrca. 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. It makes sense as all of us know that the most humid rooms in the house like the bathroom and kitchen need it. While hardly anybody agrees on the best roof ventilation system everybody agrees some roof vents do hardly any good at all.

Take for example ridge vents. 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. Any type of roof from tpo to epdm can be either hot or cold. So i ll start by saying something that might sound controversial but really isn t.