An enormous quantity of rainwater falls on your roof. Without a rain gutter, it all gets dumped right next to the foundation. The most popular gutter options are aluminum and vinyl systems. Of those two, a vinyl system is probably the easiest to install and the sturdiest. Vinyl systems are typically available in white or brown, but can be painted with 100 percent acrylic latex paint. (Note: Painting them eliminates the maintenance-free benefit.) They are available in two or three profiles, with internal or external (hidden or visible) mounting brackets.

There are two standard widths - 4-inch for roofs up to 750 square feet in area, and 5-inch for larger roof areas. It's better to err on large side if you live in areas subject to downpours or if gutters are likely to become clogged with leaves; and increase the number of downspouts above the minimum guidelines of one per 30 to 40 feet. If you live in snowy/icy areas, also go above the minimum recommended number of hangers. The roof must have an effective drip edge so water will drop into the gutter. Several manufacturers offer a combination leaf-guard/drip-edge. To determine the area of a roof plane, multiply length times width - but don't walk on a roof to get the distance from peak to eaves. Just count the number of roof courses and multiply by the exposure.

Tools and Materials

Ladders
Tape measure
Chalk line
2-foot spirit level
Goggles
Drill/driver and bits
Fine-tooth saw
Gutter system

Before You Begin: Ask your supplier for an estimating and installation guide so you can generate a shopping list. Round up a couple of ladders that will allow you and a helper to work comfortably at the roof edge -- measuring and installation are both two-person tasks. Ideally a gutter should be pitched 1/16 inch/foot for drainage. But the outer top edge of the gutter ideally should line up with the roof plane and, therefore, be level. Most people prefer a level installation, which will drain better and looks better. It's your call.

1. Establish a Level Line: Place a straightedge flat on the roof and so it extends about 6 inches over the roof edge. Hold a drop outlet in position against the fascia and slide it up until the outer edge contacts the straightedge. Mark the location of the mounting holes with a pencil. Do the same at the other end of this roof section. Stretch a chalk line between marks; check that it is level; and snap a line.

* Tip: The drip edge should extend 1 to 2 inches beyond the fascia. If there's too much roof overhang, pad out the gutter with wood blocks on the fascia; if there's too little, extend the drip edge.

2. Install Corners: To pitch a gutter, measure the length of the roof section. Position any corners on the guideline and secure them to the fascia with rust-resistant screws (here an inside corner is shown). If your fascia is angled, or if there are exposed rafter tails and no fascia board, manufacturers supply special accessories or hangers that allow the gutter to be installed at the proper angle. the end where you'll put the drop outlet, lower the line1/16 inch for every foot of length. Then snap the guideline.

3. Install Drop Outlets: Similarly, align and fasten all the drop outlets at the planned locations. You'll need one outlet for every 30 to 40 feet of gutter. This one is at the end of a run. On a very long-run roof edge, you might choose to install an outlet at each end. Then either install the gutter level or pitch it from a high point in the middle.

4. Install Brackets: Install brackets on the fascia spaced between 30 and 36 inches apart (24 and 30 inches apart, if you live in an area that gets heavy snow). Align each bracket with the guideline and fasten it with a rust-resistant screw. An external bracket is shown here; you may choose to use hidden brackets, which are also secured with screws.

5. Install Gutter Sections: Starting at an end or corner, snap a 10-foot gutter onto the brackets. Attach a connector to the end of the gutter (left). This style hooks over the back of the gutter; then it is wrapped around the gutter, snapped over the front edge and screwed to the fascia. Install each additional gutter section and connector this way until you are less than 10 feet from the end of the run.

6. Cut Gutter to Fit: Measure to determine the proper length for the last section of gutter. Transfer the measurement to a 10-foot section of gutter (upside down), and use a fine-tooth saw such as a backsaw to cut it to length. If you have a miter box, use it to guide your cut. When you complete the cut, file off any burrs and install it. Wear goggles when cutting.

7. Attach End Caps: Lubricate the seal and attach an end cap on the drop outlet (left). If there is a drop outlet or an open gutter at the other end of the run, install an end cap there, too. Repeat the above procedures until all the gutters are installed.

8. Install Elbow on Drop Outlet: Cut a short piece of downspout (or use a special bushing supplied for this purpose). Install it between the drop outlet and a 45-degree elbow.

9. Complete Offset: Attach an elbow to the top of a short downspout and hold it against the wall so the open ends of the two elbows face each other. Then measure the length of downspout for the offset, and the length of downspout(s) to extend from the elbow to just above the ground. Cut the downspout lengths, install the elbow between them and attach that assembly to the elbow on the outlet.

10. Optional Elbow: If you live in an area where leaves are likely to land in your gutter and if your downspout is connected to a closed drain that could get clogged, consider using this special elbow instead of a standard one. The angled grate forces leaves out the front opening but allows water to continue on its path.

11. Attach Downspout to Wall: Secure the downspout to the wall with a bracket at the top (near the offset) and at the bottom. On downspouts over 10 feet long, use a downspout coupler to join the sections of downspout and install a bracket at that location, too.

12. Attach Diverter: Install a 45-degree elbow at the bottom of the downspout to direct water away from the house. Then attach a hinged plastic diverter to the elbow to carry the water a few feet away. Alternately, attach a length of downspout to the elbow or let the water drop from the elbow onto a concrete or plastic splash block. Install the remaining downspouts and enjoy the rest of your weekend.

Written by Roy Barnhart, home improvement expert, Fairfield, CT.