How Far Apart Should 3 Roof Vents Be Placed

It should be noted that these vents which expel warm moist air from the bathroom and food prep areas of the home need their own ducts and vent hoods which direct air to the home s exterior.

How far apart should 3 roof vents be placed. 2 snow guards per valley every 10 feet of roof. Thus if your attic is 450 square feet you need roof vents equaling 3 square feet. In this case their height will be determined by your system. Calculate the total vent area needed.

Different forms of high and low level ventilation are used as well apart from the soffit vents and ridge vents pictured. A 50 x 30 attic would have a total area of 1 500 sq. For example if you use 16 inch by 8 inch soffit vents each vent is 128 square inches. Multiply the length of the attic times the width in feet to find the attic area then divide by 150 to find the total square feet of vent space needed.

As a general rule your roof needs 1 square foot of vent area for every 150 square feet of attic space. Ft divided by 150 equals 10 sq. Fairly simple stuff fresh air in old stale air out. Builders refer to this as the 1 in 300 rule and it requires that the total venting space should be at least shared equally between the soffit and roof vents.

Next divide the square footage of vent space required by the square footage of soffit vent you have selected. If there are gaps around the roof penetration or valley points cut extra sections of furring to fit. When finished there should be a row of furring strips stretching from one end to another with the top edge aligned at the peak. Roof ventilation this picture represents what is considered to be the best way to ventilate a roof space.

Length x width of attic in feet 150 total sq. One square foot equals 144 square inches so the standard 16 inch by 8 inch soffit vent is 0 89 square feet. Pick out your soffit vent size and determine the square footage of the vent. They should be divided equally between inlet and outlet vents and they can be used in any combination that will work with your roof s design.

Up to 45 psf ground snow load. The supply vents which push air through the duct work must be placed properly. The federal housing authority fha requirement for attic venting is 1 square foot of venting for every 300 square feet of attic space. Many have duct work in crawlspaces so the registers are placed in the floor.

Divide this by 144 to calculate how many square feet each vent is. You need to have an equal number of vents located at the bottom of the attic or under the roof easement as you have at the top of the attic near a gable or ridge. Place it two feet apart from the first row. These vents and ducts should never share space with the roof vent and air should never be vented directly into the attic.

Attic systems may use registers placed in the ceiling instead. 3 12 up to 4 12 pitch.