Measure your gutter across the top from the back where the gutter meets the home to the outer edge.
Calculate rain gutter size.
If a roof s various drainage areas call for different size gutters go for the biggest one k style.
Rainfall intensity is measured in a 5 minute interval translated.
The downspout and gutter sizing calculator is located on the tools cad and apps page of the smacna website.
Measuring existing gutters 1.
Downspout sizes must not exceed the bottom width of the gutter.
The steeper a roof s pitch the more windblown rain it can collect.
Calculate the area of a roof to work out how much guttering is required 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.
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.
15 m is a practical maximum gutter length to be served by a downspout.
Water capacity values of a gutter downspout system is calculated using the height head of water a gutter can hold the outlet orifice size of the downspout and the quantity of downspouts used.
Find the width of the gutters.
Measure the height of.
Then use the chart below to see what size gutter you need.
The saf perimeter systems gutter downspout capacity table click to enlarge relates downspout size to gutter sizes.
5 inch standard k style gutter shop 5 gutterbrush.
Multiply the drainage area by the roof pitch factor and rainfall intensity to find out the adjusted square footage.
See photos below most residential gutters will measure approximately 5 inches across the top with the actual opening being approximately 4 5 inches.
In response smacna s technical resources department has created a free downspout and gutter sizing calculator.
How to calculate gutter and downspout capacity step 1.
To limit the effects of thermal expansion in gutters 50 ft.
Box gutter with rain water head at end of box gutter.
5 inch 5 520 square feet.
Find the rainfall intensity for your locale.
Multiply the drainage area by the roof pitch factor and rainfall intensity to find out the adjusted.
Run the tape measure from 1 corner of the gutter as far as you can go toward.
Measure the roof to get the watershed area the area from which water will run off.
Measure the length of each gutter run.
6 inch 7 960 square feet.
Adjusting for pitch and rainfall.
Calculations are based on level gutter capacity as experimentally determined by the national institute of standards and technology nist.
Multiply length peak to.
Place a sturdy 20 ft 6 1 m ladder on 1 side of your house so that you can reach.
