When you purchase your siding, make sure to pick up an instruction booklet. Though each brand comes with its own directions, the requirements and techniques for installing both aluminum and vinyl are pretty much the same. The surface to which the panels attach must be smooth so that they lie flat. For aluminum and vinyl, 3/8-inch foam board insulation is a reliable backing choice.

Tools
For major cuts, you will need a radial-arm saw or a circular saw with a fine-tooth blade; for smaller cuts, tin snips or aviation shears. For tiny cuts, simply score the material with a sharp utility knife and bend it back and forth until it snaps in two. Cut corner posts and heavy trim with a hacksaw. To bend aluminum, rent a brake from a home improvement center.

Fasteners
Only aluminum nails should be used with aluminum siding. The nails should have 1/8-inch shanks, heads at least 5/16 inch in diameter, and be able to penetrate backing by at least 3/4 inch. In general, 4d (1 1/2-inch) nails will do the job. When nailing aluminum panels, place the nails in the middle of the nailing slots and do not drive them in all the way. Siding panels should hang from the nails, not be nailed fast.

Trim
The trim that goes around the foot of the house is installed first. The siding panels fit into these pieces before being nailed in place.

Posts
Position posts at corners, and suspend them by two nails driven into the uppermost slot. After checking for vertical level, nail every 12 inches. If you need to stack posts, cut 1/4 inch from the bottom of the top post and position it so that it overlaps the lower post by 1 inch or so.

Starter Strip
Snap a level chalk line no less than 8 inches above ground level. Align the upper edge of the starter strip (for horizontal siding) or base trim (for vertical siding) along the line. Nail every 6 inches. At corners, leave 1/8 inch between the panel end and the corner post for expansion.

Door & Window Trim
Before installing door and window trim, first caulk around the openings to create a moisture- and air-proof seal. Install the tops first, then the sides, and then the bottoms of the window surrounds. Along the tops, install J-channel trim with horizontal siding and base trim with vertical siding. Cut the trim so it is two channel widths longer than the opening’s width; miter or cut tabs at the ends. Nail the trim every 12 inches on center. Nail the side pieces every 12 inches, placing the top nail at the top of the nailing slot and all other nails in the center of the nailing slot. If the top is mitered, miter the sides as well. At the bottoms of windows, install under-sill trim for horizontal siding and J-channel trim for vertical siding.

Trim Under Eaves & Rakes
For horizontal siding, install F-channel trim at the soffit and gable rake. For vertical siding, install J-channel trim. Nail every 12 inches on center.

Horizontal Panels
Fit a panel into the starter strip and securely lock it in, leaving 1/8 inch for expansion where it falls into the J channel. Some sidings come with insulating backerboard; if yours does, place it beveled edge down between the panel and the wall.

End Joints
Overlap succeeding panels by 1 inch as far from a wall’s focal point as possible. If you are overlapping panels, allow for expansion by cuting 1 1/2 inches off of the nailing flange at the end of the overlapping panel. When you come to a joint, slip the backer tabs with the flat side out behind the joint, which will make the panels more stable when they span a long distance. Try to stagger joints at least 2 feet from course to course for added stability.

Panels Around Openings
When you come to windows and doors, trim the panel with tin snips or a power saw, leaving 1/8 for expansion. Use gutter-seal adhesive to affix panels directly under windowsills and at soffits. If the space is narrow, simply slip the panel into the trim on one side and then nail down the other side of the trim as succeeding panels are installed.

Top Panels at Eaves
To figure out how wide the panel just under the eaves should be, measure from the eaves in several places to the the bottom of the top panel’s top lock. Cut the panel to fit, subtracting 1/8 inch for expansion, and then slip it into the trim. Cut panels at the necessary angle so they fit into the J or F channels or into the quarter-round mouldings along the gable rake.

Vertical Panels
Installing vertical siding, like horizontal siding, begins with the trim and then the corner posts. When they have been installed, measure to find the mid-point of each wall, and draw a vertically level line down the center using a straightedge as a guide. Center the starter panel on the line, cut it 1/8 inch short to allow for expansion, and nail every 8 inches into the top of the nailing slots.

Cut succeeding strips so they will rest on the base trim and have 1/8 inch at the top for expansion. Working out from the starter, insert the top of each panel into the J channel at the top of the wall and rest the other end against the base trim. Lock each panel into the previous one as you go, and then drive nails into the centers of the nailing slots every 8 to 16 inches as is recommended by the manufacturer. Install panels around windows and doors as detailed under the Horizontal Panels section above.

As you approach a corner post, you will install a J or U panel or under-sill trim in the slot on the post, whichever is recommended by the manufacturer. Shim a J panel about 5/16 inch to keep it on the same plane as the other channels. Uncut panel edges insert into the J panel; cut edges insert between the J panel and the outer flange of the post.