How to Install Vinyl Siding Over Existing Vinyl Siding and Is It a Good or Bad Decision?

Remove the old J-mold, vinyl corners, prying them off with a nail bar. Pull nails that remain in the boxing beneath.

Pull off the bottom strip of vinyl siding along with the starter strip beneath it. To remove the bottom piece of siding, use a vinyl siding removal tool, sometimes called a zip tool. Wedge the tool between the bottom piece of siding and the piece directly above it, sliding the tool from side to side to separate the interlocking edges.

Snap vertical chalk lines on the existing siding over the location of the wall studs. Use a stud finder to locate the studs, which should be 16 inches apart.

Install 1/2-inch wood cleats around doors and windows and at the top of the wall where you removed the old J-mold. Install new J-mold on top, in the same configuration as the molding you removed.

Attach two 1/2-inch wood cleats vertically along the boxing where you removed each old vinyl corner. Position each cleat about 1 inch from the actual corner of the house. Install the new vinyl corners on top.

Nail a 1/2-inch-by-3-inch treated board along the bottom of the wall where you removed the starter strip. The bottom of the board should be flush with the bottom of the existing sill plate.

Install a new starter strip on top of the treated board, with the bottom of the strip 1/2 inch below the bottom edge of the treated board.

Snap the bottom of the first siding strip over the lip of the starter strip. Slid the strip into the corner mold, leaving a 1/4-inch gap between the end of the siding strip and the corner for future expansion.

Secure the siding strips with two 1/2-inch roofing nails, but do not drive the heads of the nails deeper than the nailing flange. Vinyl siding hangs, it does not attach tightly to the wall. Because you’re installing new vinyl over existing vinyl, it’s even more important to keep the heads of the nails from going too deeply. Drive one nail into the nailing flange over every chalk line.

Overlap the next siding strip in the row about 2 inches. The tops of the nailing flanges are about an inch shorter than the siding on each side, and they will meet when you overlap the strips correctly.

Measure each strip at the end of a wall, or where it meets a door or window, and cut it 1/4 inch shorter to allow expansion room at the end. The beginning and the ends of the strips will tuck under the new J-mold to conceal the cut ends.

Continue measuring, cutting and installing siding strips all the way up to the top of the wall, and then cut the uppermost strip of siding lengthwise to fit the remaining space. Slide the cut side up and under the J-mold.