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Applying Sheet Siding

Large hardboard and plywood sheets cover a wall rapidly. Most sheets are only 7/16 inch thick, minimizing trim problems around doors and windows. To install sheet siding yourself, you’ll need to know basic measuring and cutting techniques, and you’ll need an assistant to help handle the sheets. Some sheets come with rabbeted edges that interlock to make a vertical shiplap joint. Others simply butt together, and their seams are covered by a batten strip or special T-shaped molding.

Ideally, sheets should be nailed to studs, spacing nails 6 inches apart on edges and 12 inches apart on intermediate studs. If the sheathing is wood and in good condition, it’s all right to nail the edges of the sheets to the sheathing only. Use rust-resistant ringshank siding nails or the color-matching nails available from the manufacturers of prefinished siding materials. Never drive sheets tightly together; allow for expansion by leaving a 1/16-inch space and caulking the gap.

Cut sheet siding with the good face down if you’re using a circular saw or with the good face up if you’re using a saber saw or a handsaw. An inaccurate cut will spoil an entire sheet, so plot dimensions on graph paper and double-check them before you begin sawing. It sometimes helps avoid confusion to hold the piece up, oriented as it will be installed, after marking and before cutting. This enables you to envision how the cuts should be made. Remember to seal the raw edges of cuts made to preprimed and prefinished sheets before installation (check the manufacturer’s specifications for the right sealer).

Tools: Hammer, drill, square, chalk line, level, pry bar, circular saw, handsaw, saber saw, block plane, caulking gun.

Shiplap joints. To attach sheets with shiplap joints, nail up the first sheet, with its shiplap flush against the sheathing, and test-fit the next sheet (whose shiplap fits over the shiplap of the first sheet). Apply a bead of caulk along the edge of the first sheet, then install the next. Don’t try to drive a nail through both laps.

Metal and plastic moldings. Metal moldings offer an inconspicuous way to finish butt joints. Some types must be installed as you install the first sheet. Others can be driven in between the sheets. Drive fasteners as recommended by the manufacturer. On a vertical installation, when the wall is taller than the length of a sheet, use metal moldings at the horizontal butt joints as well.

Wood battens. You also can cover butt joints with wood battens. Fasten the battens tightly with nails driven every 2 feet or so, then apply butyl or latex/silicone caulk to each side of the batten. For a board-and-batten effect, space more vertical strips across the sheet’s width.

Outside corners. At the outside corners, lap one 1x4 with one 1x3, as shown above. (If you use two 1x4s, one side will be wider than the other.) It is sometimes easiest to nail the two pieces together first, and then cut the assembled corner to length. Attach the corner with siding nails.

Inside corners. Finish inside corners with 2x2 trim, as shown. You can also select from a variety of cove moldings milled for this purpose.

Horizontal joints. On taller walls, such as the sides of two-story houses, you’ll encounter horizontal joints. Nail the bottom sheet down, apply a bead of caulk, lay special Z-flashing in place, and nail the top sheet.

Applying Manufactured Siding

Aluminum and vinyl sidings are designed especially for residing applications and are relatively easy to install. Check the warranty, though, to see whether you risk voiding it by doing the work yourself. The integrity of the installation depends on closely following the manufacturer’s instructions. Manufactured siding uses standardized, lightweight components that go up fast and fit together snugly, with none of the warping and splitting problems common to wood.

Metal siding must be grounded because it conducts electricity. Aluminum and vinyl sidings expand and contract considerably with temperature changes. That’s why they come with slots, instead of holes, for nailing. Locate nails near the center of these slots— and make sure you don’t drive the nails so tightly that they impede the inevitable movement. Beware of siding companies with hard-sell presentations and attractive financing arrangements. Many siding contractors are reputable, but there are plenty of fast-buck operators. Hardboard siding will swell if it absorbs condensation from within walls—install it with an adequate vapor barrier. Cut and attach it as you would wood siding.

Tools: Hammer, drill, measuring tape, square, saw, Zip tool (often provided by the manufacturer), tin snips, caulking gun.

Vinyl Shakes - Also available are vinyl components made to look like painted wood shakes. They come in various widths for a random appearance. They must be installed on smooth, wood sheathing. Like vinyl and aluminum siding, the trim pieces are installed first. The pieces interlock for quick installation; once the first course is established level, there is no need to periodically check the courses for level or the proper reveal.

Siding strips. Aluminum and vinyl sidings come in strips with interlocking top and bottom flanges for tight joints between strips. Nail one course through the prepunched holes in the top lip, then interlock the bottom of the next piece with the top of the one just installed.

Inside corners. Inside corner pieces have flanges on each side where the siding strips fit. Test that the corner is plumb in both directions before you install it. If not, draw a plumb line and shim the inside corner so it is plumb and firmly attached. Apply caulk to the back of the corner piece just prior to attaching it.

Outside corners. Cover the outside corners with continuous strips (shown above) or put individual caps over each course. In some installations the outside corners are installed first, and the siding strips are slipped into the flanges. In other installations the siding strips are cut precisely to length and installed first, and the corner pieces are added last.

Soffits. Using manufactured soffits, you can extend a new siding job up under the eaves, avoiding chronic repainting and repair problems.

Channels. Because manufactured siding is fairly thin, it presents few problems around openings. This channel fits under windowsills or eaves. Install it first, then slip the siding into its flange.

Insulated siding. Insulation-backed siding does a good job of muffling noise—a problem with metal siding. The energy-insulation factor, however, is only marginal.

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