Standard Roof Gutter Sizes

If you are worried you will need a larger gutter than the standard 6 inch it s important to talk to your roofer about your maximum rainfall intensity the pitch of your roof and the drainage area square footage.

Standard roof gutter sizes.

Welcome to gutter supply your online reference for gutters gutter machines gutter guards and accessories. Roof pitch is very important for right roof gutter sizing. Then use the information below to see what size gutter you need. The downspout and gutter sizing calculator is located on the tools cad and apps page of the smacna website.

Downspout sizes must not exceed the bottom width of the gutter. Simplified suitable for flattish roofs with little or no vertical faces or steep roofs draining to one side of box gutter only or any roof if you are in a hurry and make the necessary allowances for all catchments. They can be 4 5 or 6 inches. Calculations are based on level gutter capacity as experimentally determined by the national institute of standards and technology nist.

Box gutter with rain water head at end of box gutter. You can measure pitch with a 2 foot level and a tape measure. Downspouts also come in different sizes such as 2 3 inches and 3 4 inches in size. 5 inch 5 520 square feet.

Hold one end of the level against the roof level it and then measure the distance between the roof and the underside of the level at its midpoint which. The steeper a roof s pitch the more windblown rain it can collect. If a roof s various drainage areas call for different size gutters go for the biggest one k style. Downspout sizes are based on table 1 3 dimensions of standard downspouts page 1 4 of the architectural sheet metal manual 7th edition.

Multiply the drainage area by the roof pitch factor and rainfall intensity to find out the adjusted square footage. Downspout sizes must not exceed the bottom width of the gutter. Multiply the drainage area by the roof pitch factor and rainfall intensity to find out the adjusted square footage. 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. Outlet sizing and spacing your gutter system will perform its best when a proper outlet size is chosen to drain a given roof area. Common in half round gutters the 6 inch isn t the largest size gutter available but for most homes it does the job. 5 inch 5 520 square feet.

6 inch 7 960 square feet. When you are completing a gutter replacement the first point to note is that gutters come in different sizes.