Measure the depth of the eave overhang from the edge of the roof not the gutter straight back to the outside wall.
Gutter to roof line.
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But houses with big steep roofs or those located in climates prone to heavy downpours may need wider gutters and extra downspouts to keep rainwater from overflowing.
Water will blow in there and rot the timber facia.
Gutter placement people usually think that gutters should be placed right on the roofline.
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.
Below the shingles on the high side of the gutter run.
Amerimax contemporary 4 in x 5 875 in white half round gutter end with drop.
For every 10 feet of gutter from this measurement and mark this distance at the low end of the gutter run.
Slope the gutter down form there towards the spout.
When installing gutters set the proper slope by driving a nail 1 2 in.
Mount the gutter so that the edge without the downspout is slightly higher than the end with the sleeve.
If the gutter is tilting away from your house it could be causing an overflow particularly during heavy storms.
For example if you have 30 feet of guttering the calculation is 1 4 x 3 0 75 i e.
Amerimax 5 5 in x 10 in brown k style gutter end with drop.
The pitch and tilt of your gutters make all of the difference.
Gutters should be hung where a straight edge laying on your roof shingles can easily extend over the front lip of the gutter this is the proper installment location for the high point of the gutter.
2 your gutters aren t positioned correctly.
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This is incorrect because rainwater pulls back up on the underside of the roof and it drips down under the roof.
Attach the gutter strip to the fascia or roof edge with nails and gutter straps.
In almost every instance gutter installers take the path of least resistance and shove the gutter right underneath the roof shingles instead.
Five inch k style gutters or 6 inch half rounds the most common residential sizes are able to handle the rainfall on most houses in most parts of the country.
In turn rainwater will run behind gutters that hang too high deteriorating the fascia boards along the way.
If the eave overhang is 12 inches deep multiply the roof line measurement determined in step 1 by 4.
If the eave is between 12 and 24 inches deep multiply the roof line measurement by 5 3.
This means the downspout end of the gutter should be set 3 4 of an inch lower than the other end.
The pitch of gutter heading towards a downspout can also cause overflow if it s too steep.
If the run is long you may need flashing to cover the exposed part of the facia.