Evaluate and plan the project
Gutter replacement, which involves installing your own rain gutters can save you substantially over professionally installed gutters, but there are a few pitfalls to watch out for. Inspect the fascia and soffit (Fig. B) for signs of rotted wood, which will need to be replaced before you put up the rain gutters. Many houses have a trim board or crown molding nailed to the fascia just under the shingles. You’ll have to either remove this as we did or add a continuous strip of wood under it to create a flat plane for the gutters. In either case, prime and paint bare wood before you hang the gutters.
Draw a sketch and measure your house
Fig. A shows an example of a rain gutter system for a typical house. Record the length of the rain gutter runs and mark the downspout locations. Then count up the inside and outside corners and end caps (note whether they are right or left ends). Measure the height of downspouts and add 4 ft. to each for the extension away from the house at the bottom. Each downspout requires three elbows. There are two types of elbows that turn either to the front or side of the downspout. Most installations require only front elbows, but occasionally you may need a side elbow, usually to turn the downspout extension sideways. Here are a few planning tips:
Locate downspouts in unobstructed areas where water can be directed away from the house. Avoid locations with obstacles like electric meters, hose bibs or sidewalks.
Place downspouts in inconspicuous locations if possible.
Install oversized 3 x 4-in. downspouts on gutters that drain large roof areas or if you live in an area with torrential rains.
Slope long gutter runs (40 ft. or more) down both directions from the middle and put a downspout on each end.
Buy special roof hanger mounting straps for houses without fascia boards or for fascias that aren’t vertical.
Gutter Parts and Mounting Details
Measure the horizontal rain gutter runs and downspouts and identify the parts you’ll need.
Cut the front and back sides with a tin snips. Bend the gutter and cut the bottom.
It’s much easier to join sections on the ground than to work from the top of a ladder. Photos 1 – 8 show how. Instead of butting parts together and covering the joints with a seam cover as recommended by the manufacturer, lap all seams from 2 to 4 in. Then caulk and rivet them together (Photos 3 – 5). We’ve shown joining a gutter section to a corner. Use the same process to join two sections of gutter, except overlap the pieces at least 4 in. When you’re splicing gutter sections, plan ahead to leave the best-looking factory-cut end on the outside if possible. Also lap the rain gutters so the inside section is facing downhill to prevent water from being forced out the seam.
Where a gutter ends, cut it to extend about an inch past the end of the fascia board to catch water from the overhanging shingles. Then attach an end cap with rivets and seal the joint from the inside with gutter sealant.
Gutter Replacement: How to Install Gutters
Photo 6: Mark the downspout outlet
Mark the center of the downspout outlet on the bottom of the gutter. Center the outlet, flange side down, over the mark and trace around the inside. Cut a V-shaped notch with an old chisel as a starting hole for the tin snips. Place two short scraps of 2×4 side by side under the gutter to support it while you chisel the notch.
First measure from the corner of the house to the center of your chosen downspout location. Double-check for obstructions. Transfer this dimension to the gutter and cut in a downspout outlet (Photos 6 – 8). This method takes a few minutes longer than using one of the short gutter sections with a preinstalled outlet, but it eliminates two seams and looks much neater. You can make this cutout with a duckbill tin snips, but a special offset snips like we’re using (available from hardware stores and home centers) is much easier for beginners.
Gutter Replacement: How to Install Gutters
Photo 9: Mark the gutter slope
Set the proper slope by driving a nail 1/2 in. below the shingles on the high side of the gutter run. Measure and record the distance from the bottom of the fascia board to this nail. Subtract 1/4 in. for every 10 ft. of gutter from this measurement and mark this distance at the low end of the gutter run. Drive a nail at this mark and stretch a chalk line between the two nails. Align a level with the string to check the slope. The bubble should be off-center toward the high side. If it’s not, adjust the string until the bubble indicates that you have the proper slope. Finally, snap the string to mark a line on the fascia board.
The number and size of downspouts determines how fast your gutters will empty. Sloping them helps eliminate standing water that can cause corrosion and leak through the seams. Slope each gutter run down toward the downspout about 1/4 in. for every 10 ft. of gutter. If your fascia boards are level, you can use them as a reference for sloping the gutters. Check this by holding a level against the bottom edge. If they aren’t level, adjust the string line until a level aligned with it shows a slight slope (Photo 9). Snap a chalk line to indicate the top of the gutter. Then straighten gutter sections as you screw them to the fascia by aligning the top edge with the chalk line (Photo 10).
Flashing protects your fascia and soffit from water damage
With gutter replacement, you can prevent water from running behind your gutters by installing a metal gutter apron flashing under the shingles and over the back edge of the gutter (Photo 11). If your home center or hardware store doesn’t sell prebent flashing, ask an aluminum siding contractor or local sheet metal fabricator to bend some for you. Ideally the flashing should be slid under both the shingles and the roofing paper or ice and water barrier. If this isn’t possible because the ice and water barrier is stuck to the sheathing, or there are too many nails and staples along the edge of the roofing paper, then just slip the flashing under the shingles (Photo 11). If the flashing you’re using is too short to reach down over the back edge of the gutter, slip an additional strip of sheet metal flashing under the bent flashing and over the gutters.
With the gutters screwed to the fascia, it’s a simple job to install the hidden gutter hangers (Photo 12). Install hangers every 2 ft. to support the gutters and strengthen the front edge. The hangers are designed to slip over the back edge of the gutter, but since we’ve covered this edge with flashing, just hold them level and drive the screws through the flashing and gutter back into the fascia. The large screws included with the hangers we used are a little tricky to get started, especially through steel gutters and flashing. Spin them at high speed without applying much pressure until the screw tip bites into the metal. Then lean on the drill and drive them into the fascia.
A special crimper tool eliminates downspout frustration
Photos 13 – 16 show how to install the downspouts. We’re using standard 2 x 3-in. downspouts, but the procedure for oversized 3 x 4-in. ones is the same. Assemble the elbows and downspout tube with the crimped ends facing down to prevent water from leaking out of the joints. Use sheet metal screws rather than rivets so you can disassemble the downspouts to clean them if necessary. Pros prefer prepainted 1/4-in. hex head screws with very sharp points, called “zippers” because they’re easy to install. We found these screws in the aluminum siding section of a home center, but a gutter supplier would be another good source.
You can cut downspout tubing with a 32-tooth hacksaw blade, but the pro we talked to uses a circular saw with a standard 24-tooth carbide blade. A power miter box also works great for cutting both gutters and downspouts. Use an old blade, though. Protect yourself from flying bits of metal with goggles, leather gloves, jeans and a long-sleeve shirt.
Each length of gutter and every elbow is squeezed, or crimped, on one end to allow the pieces to fit together, one inside the other. Since 10-ft. lengths of downspout are only crimped on one end, you’ll have to crimp one end of any cutoff piece to make it fit inside the next elbow or downspout section. If you only have one or two downspouts to install, you can use a needle-nose pliers to twist crimps into the end. But an inexpensive crimping tool will save you tons of time and frustration (Photo 14).
Finish the gutter job by easier to hang the downspouts. attaching the downspouts to the wall. If you can’t find U-shaped brackets, make them from sections of downspout (Photo 15). They look better than the bands that wrap around the outside and make it easier to hang the downspouts.
Gutter maintenance is the key to long-lasting gutters
Clean leaves from your gutters twice a year, or hire a company that specializes in gutter cleaning and maintenance. You’ll extend the life of your gutters and eliminate problems like backed-up gutters and plugged downspouts.