Gutters are an important part of your home's "water management system" that helps keep moisture out of your basement. Proper drainage and correct grading of your property are the other components. Gutters can be made of all kinds of materials like steel and aluminum, or even unique and expensive materials such as copper. No matter what they are made from, gutters are designed to capture water running off your roof and direct it away from your foundation.
Vinyl gutters do a fine job of channeling water, and have some added advantages in that they're inexpensive and can be installed by the average homeowner, hopefully with at least one helper.
Designing Your Gutter System
To catch the water running off your roof, gutters need to be positioned so that the edge of your roof is approximately over the middle of the gutter. With the gutter is positioned properly, it will catch any water coming off the roof, whether it's streaming off as a result of a big downpour, or barely trickling off from a shower. Gutters also need to be sloped slightly from end to end, so water flows downhill to the downspout and eventually away from your home.
Figure out how you want your gutters to direct the water flow; this determines the specific pieces of gutter connectors you'll need. Have the downspout emptying onto a hard surface like a driveway that's already sloped to drain water away. You don't want to have the water going into a naturally low spot, and you probably don't want to direct it towards your neighbor's foundation, either.
Measure your roof. Vinyl gutters generally come in 10-foot sections. Combine this measurement with your layout to determine the specific pieces you will need for your job.
Installing the Gutters
Start at the end of the gutter away from the downspout location and measure down 1/2 inch (or the distance recommended by your gutter manufacturer) and make a mark. Move to the downspout end and measure down the same distance and mark it. These two marks should be level with each other.
Remember, gutters need to slope downhill, so at the downspout end, measure down from your mark 1/16" for every foot of run (or 5/8" for every 10 feet) and mark that position. Snap a chalk line between the lower mark (at the downspout end) and the single mark at the far end. The chalk line will be your reference line for installing the gutter components.
Working from your ladder, install the components of the gutter system - corners and drop outlets (be sure this is at the lower end of the run). Also, install the mounting brackets or hangers, positioned every 24 or 30 inches (follow your manufacturer's specifications). Be sure to use rust-resistant screws and align the components with your reference line.
Snap individual sections of the gutter into the hangers and join the sections with connectors. Again, follow your manufacturer's directions to allow for expansion and contraction of the vinyl. Use a hacksaw to cut sections to lengths less than 10 feet when needed to finish a run.
Install elbows to the bottom of the drop outlet, then measure, cut and install sections of downspout to the base of the drop outlet and fasten it securely to the side of the house. Another elbow and a short section of downspout directing the water flow away from your foundation complete your installation.