Gather some basic weather information to calculate the proper size for gutters and downspouts for a house.
Calculate size of gutters.
Adding additional downspouts will require less gutter and downspout volume resulting in smaller gutters downspouts.
Then use the chart below to see what size gutter you need.
Now architects engineers designers and contractors can easily and accurately size downspouts and gutters according to the specifications in smacna s architectural sheet metal manual 7th edition 2012.
The downspout and gutter sizing calculator is located on the tools cad and apps page of the smacna website.
To choose the right size gutters for a building that doesn t already have them you can quickly calculate the drainage area of the roof and adjust for pitch and rainfall to find the adjusted square footage.
Calculate the area of a roof to work out how much guttering is required.
Multiply the drainage area by the roof pitch factor and rainfall intensity to find out the adjusted square footage.
15 m is a practical maximum gutter length to be served by a downspout.
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Downspouts also come in different sizes such as 2 3 inches and 3 4 inches in size.
5 inch 5 520 square feet.
An inch of rain is not much but it if falls in half an hour it could flood a gutter.
Multiply the drainage area by the roof pitch factor and rainfall intensity to find out the adjusted square footage.
Total roof area also affects runoff.
Please lower the maximum spacing between downspouts to see this effect.
If a roof s various drainage areas call for different size gutters go for the biggest one k style.
Then use the information below to see what size gutter you need.
To limit the effects of thermal expansion in gutters 50 ft.
Simplified app for android phones.
6 inch 7 960 square feet.
The total rainfall and how rapidly it falls will affect the runoff from the roof.
Calculations are based on level gutter capacity as experimentally determined by the national institute of standards and technology nist.
You only need a ladder chalk tape measure level paper and pen.
When you are completing a gutter replacement the first point to note is that gutters come in different sizes.
Overflow calculator for eaves gutters.
They can be 4 5 or 6 inches.
The gutter and downspout size required is highly dependent on the amount of gutter and the spacing of the downspouts.
Downspout sizes must not exceed the bottom width of the gutter.
So for a roof that is 5 m long with a height of 4 m and the roof width is 8 m which makes the half roof width 4m we can calculate the effective roof area like this.
