ESSENTIAL KNOWLEDGE
The purpose of gutter and leader (downspout) systems is to collect rainwater from the roof and direct it away from the building foundation by means of leader extensions, splash blocks, or underground drain lines.
An improperly functioning gutter and leader system can contribute to water and ice backing up against fascias and under roof shingles, can damage soffits, and can discolor or deteriorate siding materials. Faulty gutters and leaders can also lead to soil erosion adjacent to buildings and serious water and foundation displacement problems in basements and crawl spaces.
Unfortunately, gutter systems take more abuse from extreme weather conditions, particularly ice and snow, than any other component of the building envelope. They are also subject to damage from ladders and being stepped on, as well as from falling treel limbs and debris.
Gutters should be sloped a minimum of 1 inch for every 40 feet of run. Standing water may indicate a sagging or incorrectly pitched gutter.
Gutters are often sized according to the roof area they drain.
- Five-inch-wide K-style gutters are the residential industry's standard.
- Six-inch-wide K-style gutters are used for larger roofs.
- Half-round gutters are typically sized 1 inch wider than K-style to provide the equivalent capacity.
Therefore, 6-inch half-round gutters are equivalent to 5-inch K-style. Four-inch-wide K-style and 5-inch half-round gutters (with equivalent capacity) are rarely used except for small roofs.
Wider gutters may be required for certain hard surface roofing materials, such as slate and tile, or used on steeply-pitched roofs, to prevent water from shooting over the gutter. Gutters should be positioned tight against roofing materials and the fascia.
In heavy snow areas, snow guards should be used to prevent gutter tear-off. Vertical leaders (downspouts) are used to capture and distribute rain water to storm drainage systems, or by means splash blocks, to areas away from the building's foundation walls to prevent the build up of water in the soil and possible resulting structural or basement moisture problems.
Leaders are typically rectangular and of the same material as the gutter to prevent destructive galvanic actions. Connections between gutters and leaders and leaders and storm drains require continuing maintenance to assure the drain is free of leaves and debris and the connection has not become loose. Other maintenance points include the connections of leaders to the building.
Leader diameters are sized according to the roof area they drain. A rule of thumb used in the industry is that a 2-by 3-inch leader will suffice for a 600 sq. ft. roof and a 3-by 4-inch leader for 1,200 sq. ft. The typical leader size for a 5-inch K-style gutter is 2 by 3 inches, but 3 by 4 inches is preferable because it is less likely to become clogged and is easier to clean out.
Before 1960, most gutters were made of wood or metal in a "half-round" shape. During the 1960s, roll-formed metal gutter technology was introduced that allowed metal gutters to be made lighter and less expensively. Initially available primarily in galvanized steel, roll-formed gutters are now available in copper, aluminum, galvanized, and painted steel. |
Gutter profiles (above) include half-round and square, but the K-style (also called formed, Ogee, or OG) predominates because it is visually compatible with recently-built housing and adds interest to simple fascia details. Recent developments in truck-mounted roll-forming equipment have allowed gutter installers to form continuous, seamless metal gutters to fit site-measured field dimensions and individual roof profiles. |
Other than keeping gutters clean of leaves, pine needles, and debris, gutter maintenance usually involves refastening hangers that have become unfastened, repairing broken hangers, or adding new hangers where hanger spacing was excessive. Hangers come in a variety of types, including hanger and strap, hanger and bracket, spike and ferrule, and concealed hanger (below). |
The spike and ferrule, because it fastens through the gutter, is more apt than other hanger types to pull out of the fascia due to expansion and contraction of the gutter.
Concealed fasteners are becoming increasingly popular because they are easy to install, are not visible, are relatively strong, allow the gutters to expand and contract, and come in a variety of sizes and configurations with different screw and nail attachment details. Other maintenance and repair items include keeping gutter and downspout screens in place, refastening leaders, and maintaining splash blocks or connections to underground drains. Gutters deteriorate over time -- wood gutters need to be oiled, metal gutters may need local repairs.
At some time, usually when new roofing is required, the gutters may have weathered to the point where they are not functioning, are unsightly, or have significantly deteriorated. The choice of a replacement will be dictated by the appearance, value, physical characteristics, and age of the existing house.
- ADVANTAGES: Repairs are generally easy to make and are cost-effective if the damage is localized.
- DISADVANTAGES: When gutter systems show widespread deterioration and become unsightly, they should be replaced in their entirety.
INSTALL NEW WOOD GUTTERS AND LEADERS
Wood gutters are still a favorite for some traditional homes.
Typically available in a 4 by 6 inches in clear fir, gutters can also be milled from cedar or redwood. One supplier, Blue Ox Millwork, offers redwood gutters in any one of 16 standard patterns or can customize to suit.
The company recommends a scarfed joint with both sides of the splice beveled 1 /4 inch on the inside to allow a depression to be filled with butyl or other high-quality sealant. The sealant can be cut out and replaced when it fails (Below). |
The interior leg of a gutter should be 1 /8 to 1/4 inch higher than the outside leg in order to spill water outward. Blue Ox recommends that, in lieu of lining gutters, a product called Chevron Shingle Oil be used in the gutter's interior. This product will prolong gutter life by reducing the weathering while at the same time allowing the gutter to breathe.
Other products, including single-ply roofing membranes, are available that can be used to line new or deteriorated wood gutters. One of these, Deck Seal(r), a SBS rubberized asphalt membrane, as offered in 1.5-, 3.5-, and 6-inch rolls (see Product Information).
Leaders, which can be copper, black iron, or PVC, are attached to the gutter by means of a nipple screwed into the gutter's interior. Some traditionalists recommend boxing (enclosing) the leaders with wood to conceal the metal leader.
- ADVANTAGES: Appropriate for more traditional housing or where the "shingle style" predominates. A strong, straight material that provides a crisp edge detail. Properly maintained, fir can last 50 years or more and redwood twice that. The front face can be painted to match adjacent trim.
- DISADVANTAGES: May not be readily available in some areas. More costly initially than other alternatives (redwood gutters are approximately $10 to $12/ lineal ft. for 4 by 4 inches (used on West Coast) and $16 to $18 for 4 x 6 inches (plus $175 set up). Fir gutters are approximately $10/ lineal ft. Gutters and leaders require maintenance to prevent wood from drying out and checking. Heavier than other gutter materials. Not typically the choice for non-custom housing.
INSTALL NEW STEEL GUTTERS AND LEADERS
Steel gutters and leaders are available in a variety of styles, including K-style, square (box gutters), and half-round. Available materials include electroplated and hot-dipped galvanized and Galvalume(r) (approximately 55 percent aluminum, 45 percent zinc by weight).
Finishes also include plain galvanized, baked enamel, modified siliconized acrylic and polyester, and fluoropolymer coatings such as Kynar. Gauges run from a lightweight 28 ga. to heavier 24 ga., with 26 ga. being the most typical. |
Gutter assemblies include "stick" systems of components sold through lumber yards or home centers (above) with typically 10-to 20-feet gutter lengths, for installation by homeowners or small contractors, as well as seamless systems provided by installers with truck-mounted roll-formers.
While both stick and seamless systems can work satisfactorily, seamless systems have fewer joints, are apt to leak less, and are faster to install. Stick systems are, however, apt to be less expensive on single houses or small projects.
- ADVANTAGES: Steel is stronger than aluminum at equivalent thickness and contracts one-half as much. Some newer coating systems allow limited guarantees up to 50 years. Steel is popular in Northern states with snow and ice conditions.
- DISADVANTAGES: Some galvanized finishes have a limited life span (5-10 years). Hot-dipped galvanized gutters are preferred over other galvanized finishes, but are not recommended for maritime environments unless the coil has been pre-coated. Galvanized finishes are rarely cleaned or primed properly and when field painted, the paint can fail prematurely.
INSTALL NEW K-STYLE ALUMINUM GUTTERS
Aluminum gutters and leaders are by far the most popular gutter systems. Available in a variety of styles, including K-style, half-round, and a K-style modified to replace a fascia board (below).
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Coatings include baked enamel, polyester, and acrylic. Gutter thicknesses run from a lightweight 0.019 to a heavier 0.032 inch, often specified on higher-end housing. The most typical thickness is 0.027 inch. Thicknesses below 0.027 inch are sometimes used on low-end housing and are available through price-sensitive home centers for the do-it-yourself markets. Aluminum gutters are available "stick" style and seamless, with the latter being more common, especially on larger projects.
"Stick" systems are frequently offered in greater thicknesses than seamless (0.032 versus 0.027 inch) and are stronger. The benefit of seamless systems is the lack of joints (which are points of potential leaks if not maintained). Concealed hangers are becoming more popular because they are invisible and allow the gutter to expand and contract. Expansion and contraction at bracket support types that surround the gutter can lead to discoloration and wear at those points.
Spike and ferrule fittings are sometimes unsightly due to sloppy installation, and can pull out of the fascia from the significant movement of aluminum resulting from temperature swings.
- ADVANTAGES: Widely available. Low cost, and relatively easily maintained. Comes as both "stick" and seamless in many color options. Easily installed. Long-term warranties on coatings are common.
- DISADVANTAGES: Expands twice as much as steel and 50 percent more than copper. Less strong than steel or copper. Can be dented (especially in lighter thickness) more easily than other gutter materials.
INSTALL NEW K-STYLE COPPER GUTTERS
Copper has been a traditional gutter material for institutional buildings and large houses and continues to be popular for high-end custom housing.
Typically specified in 16 or 20 ounces, K-type or in half-round styles up to 8 inches wide, copper is available in "stick" as well as seamless systems. Copper has also been used as sheet flashing in "boxed" or built-in gutters (below). |
Typically allowed to weather naturally, copper develops a blue-green coloration resulting from the formation of a protective copper oxide patina. Lead-coated copper gutters are also available from some suppliers for those preferring a grey color.
According to the Copper Development Association, copper gutters are affected by the acids in red cedar shingles only to the extent that the acid may retard patination. Pitting of the gutter will not occur if recommended details are followed (see Further Reading).
Copper joints and connections are usually soldered, providing continuous surfaces, which limit the potential for leaks.
- ADVANTAGES: Considered a quality, premium product. An appropriate material for historic preservation projects. Copper patina blends well with many roofing products. Low maintenance, does not require paint. Will not rust and is well suited for maritime environments.
- DISADVANTAGES: Significantly more costly than alternative materials. Requires skilled installers for cutting and soldering of joints and transitions. Not a normal choice for other than custom applications.
INSTALL NEW HALF-ROUND COPPER & ALUMINUM GUTTERS
Half-round gutters were the traditional gutter style on homes built before 1950 and remain a popular choice on historic renovation projects, traditional renovations, and new upscale custom housing.
The simple lines of half-round gutters compliment heavily textured materials such as slate, shakes, and tiles. Where crown moldings exist in lieu of fascias, half-round gutters are hung from the roof. Where fascia exist, fascia brackets are used to attach gutters.
One company, Classic Gutter Systems, sells specially designed oversized 5-or 6-inch half-round gutters made of heavy weight 20 ounce copper and heavy weight .032 aluminum. |
They supply an extremely durable hanging systems as well as heavy weight cast brass and aluminum functional brackets in decorative and plain styles (above). These are lag bolted with stainless-steel lags into the fascia board. A full line of accessories, decorative components, and screens is also available.
- ADVANTAGES: Half-round gutters are the most efficient gutter shape and least affected by ice and snow. Appropriate for both historic rehabilitation and new construction, both contemporary and traditional. Attractive and durable.
- DISADVANTAGES: Higher initial material cost than some other gutter products. Approximately $2.25 to $2.75 for aluminum and $5 to $5.50/ lineal foot for copper (not including hardware direct from Classic Gutter Systems). Not generally used on non-custom housing.
INSTALL NEW VINYL (PVC) GUTTERS
Originating in Europe, vinyl gutter systems have a small but growing following, largely among do-it-your-selfers.
One U. S. company, Plastmo, has been the leading supplier of vinyl gutters in Scandanavia since 1959. Gutters can run the gamut from flexible to quite strong depending on the material's thickness, that runs from 0.062 to 0.089 inch.
Its great appeal is its snap-together simplicity and the limited number of tools required to cut and assemble it. Vinyl gutters are available in K-style, contemporary (" U" shapes), and half-round styles.
One small manufacturer has a half-round gutter system that can be emptied from the ground by means of a hooking device that engages a gutter that rotates on its support brackets allowing leaves and debris to fall out (see Product Information).
- ADVANTAGES: Strong and resists dents. Will not rust, chip, or peel. Lightweight and low maintenance. In use for over 35 years. Available direct from some manufacturers and at most home centers. Effective in corrosive environments. Low cost. Easy to assemble. Can be painted if necessary.
- DISADVANTAGES: Gutter stock is only available in 10-foot lengths. Visually different from more traditional gutter systems. Basically a do-it-yourself technology, with most gutter contractors committed to aluminum and/ or steel because of their investment in those systems. Perceived by some to be a lower-end product. Limited number of colors.
REPLACE/ PROVIDE GUTTER SCREENS/ GUARDS
A variety of products are available to retard the build-up of leaves, twigs, dirt, and asphalt roofing granules in gutters. Historically these have been galvanized or vinyl-coated metal or plastic screening material, but recently a host of "gutter guard" products has emerged.
These products range from slotted or perforated vinyl or metal extrusion to nylon mat filters. Additionally, some manufacturers and distributors of roll-forming equipment and metal coils have produced gutters that include protective hoods. One manufacturer, Englert, Inc., fabricates and sells through franchised dealers a 0.032-inch aluminum gutter called Leaf Guard(r) that incorporates a hood (below). |
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