Calculating Attic Size

The formula above gives an approximate value of the cfm needed for an attic fan.

Calculating attic size.

Measure the length and width of the attic floor space to be ventilated. So draw up a simple cross section showing the outside wall a rafter set at the correct pitch and a floor system. Calculate or enter the square footage of the attic or area to be vented. On a ladder beside the roof place the level a foot or so up the roof hold it level and measure from the 12 inch mark on the level s bottom straight down to the roof.

Make sure to measure in the center at the attic s highest point. How to size attic exhaust vent fans for your home attic size. 8 inches and you have an 8 in 12 pitch. Attic fan size cfm 0 7 x sq ft area of the attic formula 1 the size of an attic fan is calculated in terms of cfm.

Divide this number by two. Cfm cubic feet per minute is a measure of the amount of air the fan moves in a minute. Pitch measurement method 2. 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.

This calculator is to be used as an estimating tool only. If this distance measures 4 inches you have a 4 in 12 pitch. It s the covering on the uppermost part of the building or shelter which gives protection from pets or animals and weather notably rain or snow but heat also sunlight and wind. Next we need to calculate the 5 and 8 ceiling lines.

How to calculate the cubic feet of an attic. Click the button to calculate the depth in inches and pounds of total insulation required for this job. Input length width and desired r value of the area to be insulated. Measure the width of your attic in feet.

I ll do this on the right side of the house which is a 12 12 pitch. To determine the size of your attic multiply the width by the length of the attic floor in feet. This attic ventilation calculator computes the size and number of solar powered attic fans to achieve the proper ventilation for your attic. Attic truss room size calculator a rooftop is part of a building envelope.

Measure the height of your attic in feet. Measure the length of your attic in feet. Click to see full size image.