Then use the chart below to see what size gutter you need.
Gutter sizing roof slope factor.
Maximum rainfall conditions will be used to determine downspout size ï it is decided to drain the building with 4 downspouts located at each corner of the building.
Please lower the maximum spacing between downspouts to see this effect.
The steeper a roof s pitch the more windblown rain it can collect.
You can measure pitch with a 2 foot level and a tape measure.
Pitch or steepness also is a factor.
Then use the information below to see what size gutter you need.
In plastic k style 5 inch guttering will drain up to 5520 ft 6 inch up to 7960 ft.
An expansion joint will be installed in each gutter between the downspouts.
If a roof s various drainage areas call for different size gutters go for the biggest one.
The plan area of this building is 8500 sq ft 790 sq m.
A roof of 1 200 square feet in size will collect more water than one that is 600 square feet.
If a roof s various drainage areas call for different size gutters go for the biggest one.
Smacna s new downspout and gutter sizing calculator enables the user to manually enter the design area of the roof or use the design area wizard for the calculation.
The building is 100 x 85 ft 30 5 x 26 m with a double pitched roof having a slope of 6 in ft 152 mm m ï the slope is toward the 100 ft 30 5m side.
Sizing the gutters multiply the drainage area by the roof pitch factor and rainfall intensity to find out the adjusted square footage.
Adding additional downspouts will require less gutter and downspout volume resulting in smaller gutters downspouts.
The gutter and downspout size required is highly dependent on the amount of gutter and the spacing of the downspouts.
Multiply the surface area by the pitch factor to find the rain collection area for your roof and you can buy the right size guttering.
Locate the roof pitch slope factor for the pitch of your roof by consulting a roof pitch chart or using the following values.
Water will run off faster from a very steep roof than from one with a gradual slope.
Total roof area also affects runoff.
Sizing the gutters multiply the drainage area by the roof pitch factor and rainfall intensity to find out the adjusted square footage.
This wizard makes it easy to calculate the roof design area by providing various shape calculations and the calculation for vertical walls area per international plumbing code ipc.
Roof pitch is very important for right roof gutter sizing.
An inch of rain is not much but it if falls in half an hour it could flood a gutter.
Since the slope is 6 in ft 152 mm m factor 1 10 is used table 1 1 making the design area 9350 sq ft 868 sq m.
Thus each of the four downspouts will serve a 2338 sq ft 217 sq m area.
