Roof Square Footage Per Downspout

Pitch measurement method 2.

Roof square footage per downspout.

The 6 in 12 pitch factor 1 1 multiplied by 1 000 yields an effective area of 1 100 square feet. If this distance measures 4 inches you have a 4 in 12 pitch. A house in chicago has a roof whose actual drainage area is 1 000 square feet. For a 5 inch k style gutter the square footage should be up to 5 500 sq ft and for a 6 inch k style gutter the square footage should be upto 7 900 sq ft.

Intensity lasting calculated roof area intensity lasting calculated roof area 5 minutes drained per 5 minutes drained per downspout area downspout area in hr mm hr sq ft sq m in hr mm hr sq ft sq m sq in 100 sq mm sq in 100 sq mm 7 4 187 160 2 30 10 4 265 110 1 70 7 1 181 170 2 40 9 9 251 120 1 70 1 8 46 660 9 50 3 1 77 390 5 70. One foot of 5 k style gutters holds 1 2 gallons of water. 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. To do that simply multiply drainage area calculated earlier by roof pitch factor and rainfall intensity.

Gutters come in a wide range of materials the cost depends on which you choose. A square inch of downspout can drain 1 200 square feet of roof during a rain with an intensity of one inch per hour. 8 inches and you have an 8 in 12 pitch. Primary cause for water spillage is debri in the gutter.

A large roof is going to move a lot of water which means the downspout locations may need to be adjust to compensate. One foot of 6 k style gutters holds 2 0 gallons of water. Metal gutters vary in price from 6 to 12 for aluminum and 9 to 20 for steel to 25 or more for high end copper. Labor costs vary based on the type of underlay at 0 15 to 0 22 per square foot.

Vinyl gutters cost 2 to 5 per linear foot. For the vast majority of rains gutter and downspouts sizes considerably less than recommended will do the job. Roof area the locale s rainfall intensity and gutter capacity determine how many square inches of downspout are needed. Therefore this roof should be equipped with 6 inch k style gutters.

It doesn t take many sticks leaves or needles to impede the proper flow of water in the eavestrough. Multiplying that number by the local maximum rainfall intensity 6 8 inches per hour yields an adjusted square footage of 7 480 square feet. There is a range of different solutions for roofing underlay some are tacked or stapled while others are self adhesive ranging in price from 0 18 to 0 49 per square foot for materials only. Size downspouts to fit the gutter.

Doubling the number of downspouts halves the required capacity for each. Two hundred feet of gutter can cost anywhere between 660 and 4 500. Multiplying that number by the local maximum rainfall intensity 6 8 inches per hour yields an adjusted square footage of 7 480 square feet.