The good news: Gutters come in all shapes, colors, and prices, so you can easily find a match for your style of house and budget.
Unfortunately, figuring the right sizes of the gutters and downspouts for your roof involves some head-banging mathematical formulas.
Not to worry. This guide will put you on the path to gutter glory. If you’d like to do your own calculations for sizing your gutters, we’ll help you through it.
Basic Types of Gutters
Let’s start with shapes. There are two basic types, and they’re referred to by the shape of their cross section. Both types come in five-inch and six-inch widths.
1. K-style gutters have flat bottoms and backs, and the front side of the gutter usually has a decorative shape, such as a curve or ogee, that mimics crown molding. You can choose from many styles.
2. Half-round gutters are exactly what the name suggests: half-round tubes. These are often found on older, historic homes.
In general, K-style gutters have twice the capacity of their half-round cousins of the same width, and cost up to 50% more per linear foot.
Gutter Materials
Residential gutters are made from various metals, including:
Aluminum
- Most widely used material
- Lightweight and easy to install for DIYers
- Won’t rust
- .032- or .027-gauge thickness recommended for long-lasting duty in regions with snow
- Comes in various colors and can be painted
Cost of materials if you DIY: $2 to 3 per linear foot (6-inch K-style) including downspouts
Cost of pro install (materials and labor): $4 to $9 per linear foot
Copper
- Exceptional beauty
- Won’t rust
- No need to paint; will develop a patina over time
- Needs pro installation; seams and joints must be welded
- Used primarily on high-end residences and historic restorations
- Pricey
Cost of pro install (materials and labor): $12 to $25 per linear foot (six-inch K-style)
Seamless Aluminum
Seamless (or continuous) gutters are made at the job site. A truck with a spool of flat aluminum pulls up to your home, and the fabricator uses a gutter-forming machine to custom make whatever gutter length is required. There’s no hauling of long gutters. About 70% of all gutter installations are the seamless type.
Installing seamless gutters:
- Eliminates many seams and reduces chances of leaks
- Costs slightly more than regular aluminum gutters
Cost of pro install (fabrication and materials): $5 to $11 per linear foot (6-inch K-style)
Steel
- Strong
- Galvanized steel resists rust, but longevity is an issue; may start to rust after five to 10 years
- Many color options; can be painted
- Heavy and not recommended for DIY
- Can be pricey
Cost of DIY materials, including downspouts: $4 to $6 per linear foot (six-inch K-style)
Cost of pro install (materials and labor): $8 to $10 per linear foot
Vinyl
- Lightweight and inexpensive; good for DIYers
- Not many colors to choose from
- Color susceptible to fading from UV sunlight
- May crack in severe cold
- Won’t support ladders placed against them
Cost of DIY materials, including downspouts: $1 to $2 per linear foot (six-inch K-style)
Cost of pro install (materials and labor): $3 to $5 per linear foot
Zinc
- Durable and long-lasting
- No need to paint; will develop a patina over time
- Needs pro installation; seams and joints must be welded
- Used primarily on high-end residences and historic restorations
- Expensive
Cost of pro install (materials and labor): $10 to $24 per linear foot, six-inch half-round (K-style not available in zinc)
Downspouts
Downspouts come as either round or square, in widths from three inches to six inches. The most common sizes are rectangular:
- Two inches by three inches
- Three inches by four inches
Decorative varieties, such as spiral shapes, are available.
The size and number of downspouts you’ll need depends on the capacity of your system.
Rule of thumb: You need one downspout for about every 30 to 40 linear feet of gutter. To increase the capacity of your gutter system, add more downspouts.
How Much Gutter Do You Need?
Figuring gutters sizes and capacities is a complex brain-freeze equation involving the size and slope of your roof and the average maximum rainfall your area can expect. We recommend leaving the calculations to your gutter installation professional.
For the most part, you won’t go wrong with a five-inch, K-style gutter. “A five-inch gutter is pretty standard and will handle rainfall just about anywhere in the country,” says Bill Sheetz, owner of Lake Cook Exteriors in Palatine, Ill. He uses them on “almost all our installations.” And he specs oversized (three-inch-by-four-inch) downspouts to ensure good drainage.
Sheetz says a six-inch gutter has almost twice the capacity of a five-inch, but cautions that in cold climates, larger gutters run the risk of getting weighted down with ice, which could damage the gutter system. Moving to a six-inch gutter increases costs by about 25%.
For those of you who are self-reliant DIYers determined to do the calculations, these step-by-step instructions will take you through the process.
Or try this online gutter and downspout calculator.
Related: Downspouts with Style