Installing Gutters

Here are the essential parts of a gutter. Make a rough drawing of your gutters and downspouts to help you remember all the parts you will need, including corners, straight connectors (or couplings), endcaps, drop outlets, brackets, downspout sections, couplers, and elbows.

On the fascia at the farthest point from the downspout, measure down from the drip cap 1/2 inch per 8 feet of gutter run or as recommended by the manufacturer. Snap a chalk line along the fascia and use a level to check the line for proper slope. Or use a line level to snap a level chalk line, measure down from it, and snap a guide line as shown. (Alternatively snap a line marking the bottom of the gutters.)

Attach a drop outlet at the low end of the chalk line where you want the downspout to be. Depending on the location of the downspout, you might be able to simply add a cap to the drop outlet or you might need to attach a short length of downspout and then a cap.

Attach any outside corners, aligning them with the chalk lines. Make sure they slope down toward the downspout. Drill pilot holes and drive screws into framing members if possible. Attach inside corners in the same way.

Attach the gutter brackets to the fascia; for extra strength drive long screws into rafter ends. Align the tops of the brackets with the sloped chalk line. Install three or four brackets for every 10 feet of gutter. (With some gutter types you will to first install the brackets onto the gutters and then attach the gutters.)

Measure the length of a run (from end to end or from an end to a corner), taking into account how far a gutter will insert into a corner fitting. Cut one of the gutters to length as needed and dry-fit all the gutter sections and the connectors. Once you are sure of the length, disassemble the parts. Apply seal lubricant to the rubber seals of the joints.

Some systems attach together using cement, also called solvent, because it actually welds the pieces together (much as you would join PVC pipe). Dry-fit all the pieces and make sure they are the right lengths, then apply adhesive and join the parts. Once they have fully cured, the joints will be as strong as the plastic.

Slip the joints onto the gutters. Be sure to align them correctly so water will flow easily downhill. You may choose to assemble an entire run on the ground or just assemble some of the parts, install them onto brackets (next step), and assemble the rest of the parts in place against the fascia.

Working with a helper, position a workable length of gutter onto the drop outlet, brackets, and perhaps a corner. Check the alignment, then push the pieces together.

Drive screws through each gutter connector and into the fascia using the screw hole provided.

To cut a vinyl gutter, use a chop saw, a hand miter saw with miter box, or a hacksaw (shown). After cutting, use a knife or putty knife to scrape away all the burrs so the cut end can seat fully into a fitting.

Where a downspout needs to be offset from the end of a run, install a bracket near the end of the fascia. Cut a short section of gutter, attach an endcap, and attach to the drop outlet.

To measure for the length of downspout that reaches to the house wall, attach a 45-degree downspout elbow to the drop outlet. Hold another 45-degree elbow against the house. Slip a downspout section onto the second elbow and mark where it needs to be cut so it fits into the first elbow.

Cut the downspout sections to fit and attach them to the fittings using lubricant or cement, as needed. Leave about 1/4 inch at each joint for expansion. Attach the downspout to the house near the elbow by slipping on a downspout bracket and driving two screws into siding or trim.

The elbow at the bottom of the downspout should be about 6 inches above grade or at the right height so the downspout extender (next step) will be sloped at a rate of at least 1/2 inch per foot.

At the bottom install a length of downspout resting on a plastic or concrete splash block. To further direct water away from the house, use a flexible extender.

Manufacturers recommend a downspout every 20-30 feet. If a run is longer than that, consider installing a downspout near the middle. Install the gutters on each side so they slope down to it.

If you live in an area that gets heavy rain or if your old gutters sometimes back up, consider installing high-flow drop outlets and extra-wide downspouts.