Joining gutter sections together is a fairly simple job. When installing metal gutters, the process involves overlapping the two pieces and riveting them together. PVC or vinyl gutters are designed to snap together easily but may require the use of gaskets or a sealant to ensure a waterproof connection. Standard gutters come in 10-foot sections, so you'll need to connect sections of gutter to span longer areas. You can instead opt to have gutters made to a custom length, but this costs a lot of money and is generally unnecessary. Metal gutters are easiest to install when all of the sections in a run are assembled on the ground before mounting. This is much easier than attempting to do the work while on a ladder. Vinyl gutters, however, are joined after they are hung.

gutter system
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Metal and vinyl gutters require different joining techniques.

Metal Gutters

Step 1

Measure the total run of the gutter length you need. If you have a straight-run gable roof, measure from shingle to shingle, and then add 1/2 inch to each side for a slight overlap. For outside corners, measure from corner to corner. If you have inside corners, subtract 5 inches. This will leave room for the inside box miter. To this total length, add 4 more inches to the length—This is for an overlap at the interior joined seam — it will make the gutter stronger in that area.

Step 2

The first gutter piece (and maybe the second and even a third piece), will likely be full 10-ft. lengths, but the last piece in the run will need to be cut with a hacksaw or tinsnips. Measure and cut this gutter piece with a hacksaw or tin snips. Remember that the total length of the gutters when put together will equal the length you need, plus 4 inches for each interior seam.

Step 3

Connect the sections of gutter, overlapping the middle seams by 4 inches. Put the best-looking gutter edge or the gutter with the factory cut on the outside.

Step 4

Apply gutter sealant where the two sections fit together. You need a tight seal so water doesn't leak through.

Step 5

Secure the gutters with pop rivets or stainless steels screws at the sides of the joined sections. Never put rivets on the bottom because they could cause the gutter to leak. Allow the gutter sealant to dry according to the manufacturer's directions. Your gutter is now the correct length and ready to install.

Vinyl Gutters

Step 1

Measure the amount of gutter you need just as you would for metal gutters. You need not allow for overlap on vinyl gutters, as the joiners will butt the edges of each gutter together.

Step 2

Install your gutters. When you get to a seam, simply hang the two gutter sections as close together as you can, butting the ends against each other.

Step 3

After installing your gutters, clean each seam using a rag dampened with alcohol. Wipe down the inside of a gutter joiner, as well.

Step 4

Apply a generous amount of plastic cement or sealant to the interior of the gutter joiner piece and then press it onto the freshly cleaned gutter seam. Position the joiner so that the seam is as close to the joiner's center as possible. Make sure the joiner snaps firmly into place. Repeat this process until all your seams are joined.