How To Tell The Size Of Gutters Your House Needs

How To Tell The Size Of Gutters Your House Needs


One square foot of your Denver or Fort Collins home’s roof can shed more than a half gallon of rainwater per inch of rainfall, according to conservationist site Graywater Action. That means a 2,000-square-foot home could drain more than 28,000 gallons of water a year. Your home’s gutters are essential to keeping your home high and dry. How big should those gutters be?

5 or 6 Inches?

Though gutters are available in many styles and designs, by far the most popular residential gutter is the K-style gutter, so called because its profile resembles the letter K. This gutter is available in either a 5-inch model or a bigger, 6-inch design.

If you do your own online investigation, you will find many claims for how much more rainwater a 6” gutter can handle than its smaller version: 40 percent, 50 percent, 60 percent. Nobody seems to know.

This difference (in water capacity) is tough to pin down for four reasons. The amount of water a particular gutter size and style can handle varies with:

  • The house roof’s pitch — This is the angle of the roof relative to the horizontal ground.
  • The rate of rainfall — as measured in inches per hour, from information available from the National Weather Service.
  • The rate of ground absorption — Gutters are not sealed bowls; they connect to downspouts and then either to French drains or your yard.
  • The roofing material on your home — metal roofs shed water faster than shingle roofs.

A steeply pitched roof sheds water faster than a low-slope roof. Rainfall intensity also affects gutter performance. Hard, packed ground absorbs rain slowly, so the collected rain may back up in your French drains, downspouts and gutters. It can also spill over your gutters, ruining your landscaping and fascia boards.

Still, no matter how you measure it, a larger gutter can handle significantly more rain than a 5-inch gutter. The “6-inch” designation refers to width and height; both are a full inch larger than the 5-inch profile, and that translates to much greater volume. 

Do You Need Bigger Gutters?

You can make your own observations about your home’s gutters from the safety of your yard. After a rain, do you see streaks of dirt and debris caused by overflowing gutters? Is the ground adjacent to your exterior walls soft, mushy, or muddy? Your gutters may be too small. 

Other things to check:

  • Wet, cracked, or damaged foundations — This one problem is very bad and worth immediate action; wet and weak foundations literally undermine the value and safety of your house
  • Ruined landscaping — Signs of gutters overflowing include damaged bushes and shrubs, soaked sod, and battered flowering plants
  • Rotten or damaged fascia boards — Using an extension ladder, you can carefully test the strength of the horizontal trim boards the gutters attach to; if these boards (your fascia molding) are damaged or rotten, your gutters are overflowing and are too small
  • How steep is your roof’s pitch? — The greater the angle (useful for shedding snow), the faster rainwater will flow into gutters
  • Metal, tile, or shingle? — Metal roofs are naturally slicker than tile or shingle, so they shed water very fast
  • Downspouts — Your home may not have enough downspouts; you need at least one for every 40 feet of gutter run, though even some stretches of gutter (under 40 feet) benefit from two downspouts at opposite ends

The decision to replace smaller profile gutters with 6-inch gutters cannot be taken lightly, but in some instances it should be — must be — taken to preserve the value of your home. Weak foundations spell disaster.

Not only do you have to weigh practical considerations, you have to think about the visual difference the larger gutters will make on your Denver or Fort Collins-area home. 

Who Can Tell?

Climbing an extension ladder is about as precarious a stunt as any homeowner should perform. For expertise in assessing your home’s gutters, contact a local gutter service contractor. Your local gutter contractor can evaluate your home’s current gutter system, checking several areas:

  • Size of gutters
  • Integrity of gutter connections
  • Strength of gutter fasteners to the fascia
  • Roof pitch
  • Number of downspouts
  • Correct slope of gutters

If you have a frank discussion with your gutter specialist, you can choose from a number of options. Your gutter contractor may recommend cleaning the existing gutters and installing gutter guards to provide maximum carrying capacity. Or, you might get a recommendation to go with new, seamless, 6-inch gutters.

With so much at stake (weak foundations are an extremely pricey problem), your gutter contractor is a great resource to help with a very important decision.

For your home in the Denver and Fort Collins areas, Red Diamond Roofing can provide a full range of roofing and exterior services, including gutters, painting, and siding. Contact us today to see what we can do for you!

Posted in Residential
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