Gutter installation should follow a couple basic rules.
Minimum gutter pitch.
Even though they look level from a distance gutters should be pitched slightly from one end to the other.
This brings up another important rule to keep in mind.
So if you have a 25 foot section of guttering you should set the downspout end of the gutter 5 8 of an inch lower 1 4 x 2 5 5 8 than the other end.
Gutters must be pitched so water will flow to the downspouts.
For a 30 foot gutter thats 1 7 8 inches of crown and ive never done that much.
This means the downspout end of the gutter should be set 3 4 of an inch lower than the other end.
Calculate the gutter slope by dividing the length of the gutter needed by 10.
To ensure that gutters drain properly make certain they slope inch for every 10 feet toward a downspout.
For example if the gutter is 16 feet long the end near the down spout must be 1 inch lower than the starting end.
Next place a ladder at the left side of the house and measure from the roof down to the gutter.
Had to edit my post as 1 8 is way too much.
But the correct answer is it depends.
In theory if your gutters are dead level the ice and mud wont be very deep.
Multiply the number of feet by 1 16 inch to determine the total slope the gutter requires.
For gutter runs longer than 40 feet it s best to pitch the gutter down from the middle to a downspout at each end.
Gutters should slope an inch or two for every 40 feet.
The rule of thumb for this slope is a vertical 1 2 inch for every 10 feet of.
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.
All guttering must slope toward the nearest downspout.
Plus it looks nicer on the facia.
Most contractors tend to set the slop at one quarter inch per ten feet of guttering.
The minimal slope needed for proper gutter drainage is 1 25 cm 1 4 inch for every 3 metres 10 feet of gutter.
Working out gutter slope as a general rule gutter slope is set at 1 4 inch per 10 feet of guttering.
If the pitch is too gentle water will just fill up in the gutters until it overflows and a too sharp pitch isn t aesthetically pleasing.