To get started measure the side of the house directly under the gutter to determine its length in feet.
Gutter pitch angle.
If you have a length of gutter that is more than 35 feet long the center point should be the highest elevation and each side should pitch down toward the downspouts on either end.
A good guideline is that the pitch should cause a decrease somewhere between 1 to 2 inches over a 40 foot run.
Technically speaking the slope also called the pitch of the gutters is the amount by which the gutters slant downward along the path of the water flow.
Gutter can be run level for appearance but addition downspout will be necessary see section on proper gutter and downspout sizing.
If the run requires two sections of gutter overlap them by 8 inches and use a 3 8 inch long self tapping stainless steel screws or pop rivets in two rows of four each to join them.
This allows the water to flow gently but.
Place the line spirit level on the string.
As a general rule gutter slope is set at 1 4 inch per 10 feet of guttering.
Gutters should be placed below the extended roof line so that snow and ice can slide clear.
If the gutter continues around a corner cut the appropriate angle typically 45 degrees on that end.
If the length of the gutter is 10 5 metres 35 feet the amount of slope required is 1 25 cm 1 4 inch multiplied by 1 metres 3 5 feet which when rounded up is 2 5 cm 1 inch.
There are two factors that go into determining gutter position on the eave the pitch of the gutter and the roof slope.
Gutter should be pitched 1 16 or greater per foot for proper drainage.
For example if you have 30 feet of guttering the calculation is 1 4 x 3 0 75 i e.
For example for every 10 feet of gutter they need to drop 1 2 inch from the high end to the downspout.
This means the downspout end of the gutter should be set 3 4 of an inch lower than the other end.
Measure from the roof edge at both ends of the gutter if you want to be sure.
As long as there is enough slope the water will naturally run out.
Gutters need to be pitched at a 5 degree angle.