How to Install Vinyl SidingUpdated: Feb. 28, 2023
Get professional-looking, watertight results with these residing techniques.
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- A full day
Working with vinyl siding
Don’t let the fact that you have vinyl siding installation deter you from that repair or remodeling project. If you want to shift a window, replace a door or even put on an addition, you can remove, alter and reinstall vinyl siding much more easily than any other type of siding. In this article, we’re going to demonstrate how to rework the siding around a new set of windows.
We’ll show you how to remove it, and learn tips for installing vinyl siding new parts. We’ll also show you how to cut vinyl siding, fit it and nail it back up. Most important, we’ll show you how to make the installation watertight.
While we’ll cover the basics, we won’t cover every detail you might run into with your own project. Most manufacturers offer complete instructions; ask for them wherever vinyl siding is sold.
Working with vinyl doesn’t require special skills, but you do have to understand the system. The only special tool you’ll need for reworking areas is an unlocking tool, often called a zip tool. (You’ll need a snap-lock punch if you intend to cover new areas.) You’ll probably need new vinyl siding trim pieces. We bought two types-J-channel to go around the new, larger windows (Photo 9), and undersill trim (see “When to Install Undersill Trim.”). You may also need additional siding.
Best Way to Cut Vinyl Siding and Installation
Vinyl siding installation is designed to hang loosely on the sheathing so that it can expand and contract with temperature changes. To prevent the relatively thin panels from buckling, observe these fitting and nailing rules.
- Leave a 1/4-in. gap at all ends. The siding slides behind vinyl siding trim pieces that hide the gap and the cut end.
- Lock the panel into the one below it, then gently snug it up before nailing. Marking the position of each piece before you remove it (Photo 2) will help you reposition the siding without stretching it.
- Center the nails in the nailing slots and drive them, leaving 1/16 in. to 1/8 in. of the shank exposed (Photo 14). The vinyl must be free to expand and contract.
Remove the siding
Photo 1: Unlock siding using a zip tool
Slide the zip tool under the butt edge of the siding, hook the locking edge and pull down. Then slide the tool horizontally along the lock to release it. Lift the unlocked siding to expose the nailing hem of the siding piece below. Draw a line on the wall along the top of each siding course before you pull the nails.
The beauty of vinyl is that you can remove a piece anywhere on the wall. Locate the piece you want to remove and unlock the one above it with the zip tool (Photo 1 inset). It might be tricky hooking the zip tool onto the locking edge if your siding is tight. Try starting at an end or look for a loose spot. Sometimes you can unzip it just with your fingers. If you’re having difficulty with a particular lock, try moving up a course. New vinyl siding is quite flexible, especially in warm weather, but older siding becomes more brittle with age, so work carefully.
It should be easy to slide a flat bar behind the nailheads since they’re not driven tight (Photo 2). Don’t slide the flat bar behind the siding itself. You’ll risk breaking it. You may have to bow each length of vinyl to release its ends from the trim moldings, and you may have to slide short pieces up or down past the window to release them from the J-channel.
Building paper and window flashing
Photo 3: Install the flashing under the window
Level and tack the new window in place then cut a piece of aluminum flashing to width so it extends from the new window to overlap the nailing hem of the siding below. Slide the top edge under the window fin, then nail off the fin with roofing nails.
Photo 4: Install flashing next to the window
Slide 5-in. wide vinyl siding flashing under the window’s nailing fin. Make sure it laps over the bottom flashing at least 2 in. and extends 2 in. above the window’s top. Nail off the window.
Building paper is an important part of the wall’s waterproofing. It’s a barrier to any water that may work its way behind the siding, so be sure upper pieces lap over lower ones. Tape any tears or holes with housewrap tape (available at home centers).
Flashing is critical for a watertight window or door. Aluminum works best with vinyl. Buy a 10-in.wide roll of aluminum (at home centers), and cut it into 5-in.wide strips for the top and sides of the window. The width of the bottom flashing will vary. It must go under the window nailing fin and lap over the nailing hem of the vinyl siding (Photo 3). This will direct water to the front of the siding.
When you’re done flashing the window, stand back and imagine water running down the wall. Start above the window and visually check that all building papers and flashing lap over the piece below it so water can’t run behind.
Install J-channel around the window
Photo 6: Notch the J-channel
Cut a section of new J-channel 2 in. longer than the width of the window. Mark out a notch 1 in. in from each end and deeply score the inner cutting line with a utility knife.
Photo 7: Finish the notches with tin snips
Make the last two cuts with snips. Bend the tab back and forth to snap it off (see Photo 8).
Photo 8: Install J-channel under the window
Position the J-channel under the window. Cut and position an undersill trim if necessary (see ‘When to Use Undersill Trim.’). Drive roofing nails every 8 to 10 in. through the middle of the slots. Don’t drive them tight. The vinyl siding trim pieces should slide back and forth slightly.
Photo 9: Cut J-channel for the sides of the window.
Cut the side J-channel 2 in. longer than the height of the window. Make the miter cut on the bottom with shears. Cut a 1-in. notch on the top end as you did on the bottom J-channel. Lap the side over the bottom as shown. Drive roofing nails every 8 to 10 in. to secure it.
Photo 10: Cut J-channel for the top of the window.
Cut the top J-channel 2 in. longer than the window width. Cut and bend the profile shown (see detail) on both ends. Lap it over the sides as shown and nail it into place.
You have to wrap the window with vinyl J-channel to divert water and to cover the ends of the siding (Photo 9).You’ll probably have to buy new strips for this. Start with the bottom piece and work up to the top (Photos 6 – 10). Make sure the pieces overlap to keep out water.
Mitered corners give a clean and finished appearance. Be extra careful to fit the top channel correctly over the side pieces (Photo 10) because a lot of water can run over these joints.
When to Use Undersill Trim
Because the siding is beveled, the cut edge under a window may end up about 1/2 in. out from the wall. If it falls 1/4 in. or less away, add the undersill trim to lock it in place (shown). If it falls more than 1/4 in. away, skip the undersill trim and simply rely on the J-channel.
If you’re working over foam sheathing, place a piece of plywood between the foam and flat bar to avoid crushing the foam.
Install vinyl siding
Photo 11: Mark the cuts for siding under the window
Position the siding to be notched below the window. Mark it on each side of the window, allowing an extra 1/4-in. gap on each side for expansion. Measure from the locking tab of the siding below to the undersill trim to determine the depth of the notch.
Photo 12: Cut the siding to fit under windows.
Cut through the nailing hem with shears, then score deeply along the rip line with a utility knife. Bend back the piece to snap off the notch.
Photo 13: Install the notched siding
Position the notched piece under the window, sliding it into the undersill trim and pushing the butt edge against the locking tab in the lower siding course to snap it in place. Make sure the top edge is on the layout line, then drive roofing nails at each stud.
Photo 14: Don’t nail the siding tight against the wall
Drive nails so that the exposed shank equals the thickness of two layers of siding (1/16 in. to 1/8 in.). Don’t drive nails all the way in.
Photo 15: Install vinyl siding over the window
Measure and notch the top piece over the window. If necessary, put a butt joint above the window to make it easier to install these final pieces. Lock the piece to the one below it, then nail it into place.
Maneuvering long pieces of vinyl into place can be tricky. Push one end of longer pieces into the trim, then bow the siding slightly and guide the other end into the trim.
Then slide it up and snap the butt into the locking edge of the piece below. Feed the shorter pieces alongside the window into the channel at the top of the window, and slide them down into position. Installing the piece above the window (Photo 15) was especially tricky because it was also the last piece (it would have been easier to remove one more course above).
We had to cut the piece and put a joint directly above the window. Then we cut a long length of extra siding to complete the row. Be sure to overlap butt joints 1 in. This method wouldn’t work if you had to splice in new vinyl, because the colors wouldn’t match.
Matching your siding
Remove a piece of siding and identify it. Take it to a siding retailer or distributor. They’ll identify the brand and style and should be able to direct you to the right source. Unfortunately, vinyl siding fades with age, so an exact color match may be impossible.
Be sure to save and reuse all the siding you remove. The vinyl siding trim pieces aren’t as critical. If you have to add new siding, position it in an obscure spot, like the base of a wall or behind the garage. In fact, you may want to re-side an entire wall with new vinyl. Don’t forget to check out our guide on replacing vinyl siding.
Required Tools for this Project
Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.
- Pry bar
- Speed square
- Stud finder
- Tape measure
- Tin snips
- Tool belt
- Utility knife
Required Materials for this Project
Avoid last-minute shopping trips by having all your materials ready ahead of time. Here’s a list.
- Aluminum flashing
- Building paper