Roof Slope Gutter Clearance

The distance below the projected roof plane varies with pitch.

Roof slope gutter clearance.

The angle of a roof on a house is referred to as the roof pitch. 12 in 12 or higher 1 3 9 in 12 to 11 in 12 1 2 6 in 12 to 8 in 12 1 1 4 in 12 to 5 in 12 1 05 flat to 3 in 12 1. Weather bureau records the maximum rainfall that could possibly happen in a 5 minute period in inches per hour for various regions. The steeper a roof s pitch the more windblown rain it can collect.

Start at the highest point with the back of the gutter as high as it will go up against the bottom of the slate or tile or galvanised iron roof. Water will blow in there and rot the timber facia. If the gutter slope isn t properly positioned it will pool in the system and spill over the sides. The general rule is to slope the gutters at 1 4 th inch per 10 feet of gutters.

If the slope is slanted too sharply the gutters can t function at full capacity. Generally a contractor that drains a gutter onto a lower roof will say that it is an industry standard whereas a contractor that rants against it will say that it s not best building practice. It s usually expressed as a number that looks like a fraction such as 1 12 for a very shallow roof or 18 12 for one that s very steep. Slope the gutter down form there towards the spout.

This means the downspout end of the gutter should be set 3 4 of an inch lower than the other end. For a steeper 7 in 12 pitch 1 2 in. You can measure pitch with a 2 foot level and a tape measure. Required clearance of gutter below extended roof line roof pitch clearance below extended roof line 0 in 12 2 in 12 1 3 in 12 5 in 12 6 in 12 8 in 12 9 in 12 or greater.

Below the projected roof plane. 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 gives you a 12 inch run. Roof pitch is very important for right roof gutter sizing. The numbers indicate the rise of the roof over it s run.

For a 1 12 roof for every 1 foot it rises vertically it runs 12 feet horizontally. So it s a matter of what the home inspector or contractor considers acceptable. As a general rule gutter slope is set at 1 4 inch per 10 feet of guttering. For example if you have 30 feet of guttering the calculation is 1 4 x 3 0 75 i e.

Roof pitch roof pitch factor. And for a 12 in 12 pitch 1 4 in. There is no building code citation that forbids a gutter from draining onto a lower roof. For a gently sloped 5 in 12 pitch place the front lip of the gutter 3 4 in.