No two buildings — or gutter systems — are exactly alike. Whether it’s a shopping mall or country club, a large estate, or a neighborhood home, every guttering project has specific needs. And though 5- and 6-inch gutters are industry standards, factors ranging from architecture to geography can affect decisions about proper sizing.

“Start by looking at the roofline,” advises Brian, owner of Gutter Brothers Seamless Gutters. “When you see the number of squares of shingles, it will tell you how many gallons of water can come off of the roof during a storm. The bigger the roof the more water it will generate.”

Since gutters exist to drain water away from buildings, then estimating the amount of water a gutter must potentially carry is a key to determining the correct size for the trough. In addition to the size of the roof, “Slope is another important factor to consider.” His own rule of thumb is 6-inch gutters for most commercial projects and 5-inch for most residential jobs. Yet different conditions may require an adjustment in gutter size.

A third consideration is the downspouts. “You should worry more about your downspout sizes rather than your gutter size,” advises owner Brian DeHart of Gutter Brothers Inc. Happily, he points out, the first chapter of the Sheet Metal and Air Conditioning Contractors National Association (SMACNA) gutter manual “has in detail the maximum rainfall for locations around the country, so that you know how many square inches of rainfall to plan for each downspout.”

In addition to considering the architecture of a structure, Brian advises installers to keep in mind the rainfall in their respective markets. “Before sacrificing the look of a home by installing a gutter that seems twice the size of the 5-inch style,” he notes, “ask yourself, ‘Am I in an area like Florida that regularly gets downpours? Or in an area like the Northeast which might get one or two torrential rainstorms per a year?’”

Some Fascia boards may not be able to support a larger gutter system.

IF YOU HEAR ANY OF THESE PITCHES YOU MAY WANT TO QUESTION THE CONTRACTOR’S MOTIVES.

SALES PITCH

SIX-INCH GUTTER WILL LET THE LEAVES AND OTHER DEBRIS WASH RIGHT DOWN THE DOWNSPOUT WITH NO NEED FOR COVERS.

IN REALITY

A LARGER GUTTER ACTUALLY WILL HOLD MORE DEBRIS THAN A STANDARD FIVE-INCH GUTTER AND IS NOT SELF-CLEANING.

SALES PITCH

FOR THOSE TORRENTIAL  DOWNPOURS 6-K STYLE GUTTER CAN HANDLE A LARGER VOLUME OF WATER THAN 5-K STYLE GUTTER.

IN REALITY  

SIX-INCH GUTTER CAN BE OVERWHELMED AND OVERFLOW. Gutters are not made to hold water, they are made to catch water and send it away Quickly

SALES PITCH

SOMETIMES A SALESPERSON MIGHT SAY THEY ARE EXPERTS IN EVALUATING YOUR ROOF AREA AND PRESCRIBING A 6″ GUTTER AS THE CURE-ALL TO YOUR PROBLEMS

IN REALITY

YOUR HOME WAS ENGINEERED BY AN ARCHITECT AND APPROVED BY AN ENGINEER BOTH OF WHOM HAVE EXTENSIVE EDUCATION AND TRAINING IN THE DESIGN AND CONSTRUCTION OF BUILDING PRODUCTS AND THEIR SUITABLE USES. SO IF YOUR HOME WAS ORIGINALLY FITTED WITH A 5-K STYLE GUTTER, IT’S MORE THAN LIKELY THAT THE ARCHITECT SPECIFIED A 5-K STYLE BECAUSE IT WAS ADEQUATE FOR YOUR ROOFS PITCH, YOUR HOMES STYLE, AND THE NUMBER OF RAINFALL EXPECTATIONS FOR THE AREA YOU LIVE IN.