When it comes to gutters, size matters. Did you know that there is more than one size gutter? That’s right. While from the street, and even up close, gutters may appear to be a single standard size, there are actually slight size differences. And if you want your gutters to effectively handle water flowing off from your roof, it is important that the right sized gutters are installed on your home.
Gutter Sizes
There are two standard gutter sizes for residential homes: 5-inch gutters and 6-inch gutters. These two sizes tend to effectively handle the water flow on most homes throughout the country. If you live in an area prone to heavy rainfall or your home’s roof is quite steep, however, you may need even larger gutters, such as 7-inch or 8-inch.
Determining the Appropriate Size Gutters for Your Home
To ascertain what size gutters should be on your home, a few calculations are required. So that you end up with the ideal gutters, we recommend retaining a gutter professional, like Superior Gutters. When we are asked to come assess the project, our team of experienced pros takes everything necessary into account so that we can advise you on the right sized gutters to do the job right.
If you would like to figure out the correct gutter size on your own, follow these steps:
1. Calculate the square footage of the gutter drainage area.
If you have a simple roof style, you figure out the square footage for each slope. If you have a roof with more than one roofline or if you have a hip roof, you will need to do calculations for each roof surface with a drainage area.
2. Determine the pitch of the roof.
Once you have calculated the square footage, you then need to account for the roof’s pitch. You will need a level and tape measure. There are two ways to calculate roof pitch: outside on the roof itself or inside your attic. To calculate it from outside, go on to the roof. You will need to determine the run of your roof by measuring up one foot from the base. Now you need to determine the rise. To do so, place the level at this one-foot measurement. Once the level is even, measure from the bottom of the level to the top of your roof. To measure your roof’s pitch from inside, you will need to access your attic and measure your rafter lengths. Place your level at the bottom of the rafter and when the bubble is centered, mark the spot at 12 inches. You will then need to vertically measure from the level to the rafter. These measurements will provide you with the number of inches your roof rises every 12 inches.
3. Now use your calculations to determine your roof pitch factor.
As an example, if your rise is six inches, your pitch will be 6/12, meaning for every 12 inches of your horizonal run, the roof rises six inches. Now see how your rise and pitch matches the list below to figure out the pitch factor:
4. Select gutter size.
To find the gutter size, multiply the drainage area (the square feet you calculated in number one above) by the roof pitch factor from the table above. If you live in an area that frequently gets heavy rainfall, you will also want to multiply this number by rainfall intensity. To determine rainfall intensity, consult with the US Weather Bureau to find out how much rain could fall in a five-minute period measured in inches per hour.
If your square footage is up to 5,500 square feet, you can use a 5-inch K-style gutter. Up to 7,960 square feet can use a 6-inch K-style gutter. If your square footage is more than that, you should consult a gutter professional about whether you should install 7 or 8-inch gutters or simply add more downspouts.
If you live in the Bergen County, New Jersey or Rockland County, New York area and need to install new gutters, or feel you may need larger gutters, give us a call.
