How To Install 12 Inch Lap Siding
Installing fiber cement siding (FCS)—such as HardiePlank®—is easier than you might think, though there are some important differences from traditional wood siding. Installation instructions may vary depending on the manufacturer, and check with your local building inspector for any code requirements.
Cottage Lap Sidings require 3 nails per board on all studs 16 in. Cottage Lap Sidings require 2 nails per board on studs 16 in. Place nails 5/8 in. Up from the drip edge and in the center of the lap. Make sure that drip edge nails penetrate both courses of siding and into studs.
- If 12-inch siding is used, the number of courses would be 61/10 = 6.1, or six courses. To obtain the exact exposure distance, divide 61 by 6 and the result would be 10 1/6 inches. The next step is to determine the exposure distance from the bottom of the window sill to just below the top of the foundation wall.
- LP SmartSide 12 in. Textured LP SmartSide 12 in. Textured Composite Lap Siding sports a cedar wood-grain texture to enhance your home's curb appeal with attractive natural look. It's engineered to resist impacts and weather better than many other siding products.
Safety First
Always follow these safety precautions when installing fiber cement siding:
- Wear safety glasses when cutting and nailing FCS.
- Use ear protection when cutting siding with a circular saw.
- Cutting FCS with a circular saw creates a large amount of dust which can lead to the incurable lung disease silicosis. Always cut siding outside and use a dust collecting saw hooked to a shop vac if possible.
- Wear a NIOSH approved N-95 dust mask or respirator when cutting FCS.
Storage and Handling
- Inspect siding carefully for damage when it arrives.
- Store off the ground, making sure it is flat and well supported.
- Keep it dry until it has been installed.
- Carry pieces on edge to prevent breaking.
- Support siding along its length when cutting.
Prep Work
- Sheath walls with plywood, oriented strand board (OSB), or foam.
- Cover sheathing with housewrap or felt paper.
- Pop chalk lines to mark the location of studs.
Cutting Siding
- Circular Saw: While this is the most common method of cutting, it produces the most dust. Use a polycrystalline diamond toothed blade made for cutting FCS. Cut from the back side using a rafter square as a guide for right angle cuts. Several pieces may be stacked and cut at the same time.
- Fiber Cement Shears: Special handheld electric shears can be used to make straight and curved cuts. An attachment called the TurboShear converts an electric drill into fiber cement shears. When using shears, cut with the back of the siding facing up.
- Jigsaw: When fitted with a carbide coated blade, a jigsaw can be used to cut holes and curves. Cut from the back of the siding.
- Scoring: Fiber cement siding can be scored and snapped like drywall, though the cuts are not very smooth. Score the face of the siding then pull up to break. A carbide tipped scoring knife lasts much longer than a standard utility knife blade.
Fastening Siding
Fiber cement siding can be nailed by hand or with a pneumatic nailer. It can also be attached using corrosion resistant screws.
- Use hot-dipped galvanized or stainless steel nails.
- Nails should penetrate through the sheathing and at least 1” into studs.
- Position nails ¾” to 1” from the edge of the siding.
- Siding can either be blind nailed at the top or face nailed at the bottom.
- Use roofing nails for blind nailing and siding nails for face nailing.
Installing Trim
Putting up trim before installing fiber cement siding.
Begin by installing the inside and outside corners on the wall. These can be made from wood, vinyl, or thicker fiber cement products such as HardieTrim®. Corners should be at least ¼” thicker than two stacked pieces of siding to allow room for caulking.
Installing Siding
Fiber cement siding should be installed 6” or more above the grade level of the house with a 1”– 2” gap between horizontal surfaces like decks, steps, or adjacent roofs. Flash above doors and windows, leaving a ¼” gap between the flashing and siding. If you’re working alone, overlap gauges can be used to support the siding while you nail it.
Begin by attaching a 1¼” wide strip of FCS 1/8” above the bottom of the first row to provide the proper angle for the siding. Next, nail the first row of siding into the studs, leaving 1/8” gaps at the corner boards to allow for caulking. Blind nailing is preferable to face nailing, since any nail heads are hidden by the next row of siding. Nails do not need to be predrilled except near the ends.
Center joints over studs unless special metal off stud joiners are used. Joints should be butted loosely together with a 4” wide strip of 30 pound felt positioned behind each one. Make sure the felt overhangs the previous row of siding to keep water from running behind it if the caulking fails.
Each row of siding should overlap by 1¼” or more. A spacer stick with a notch cut the length of the exposed part of the siding makes alignment easy.
Use a square or level to check that the rows line up at corners. When notching the siding around doors and windows, hold it in place and mark each end. To determine the depth of the notch, hook the spacer stick on the previous row of siding and measure from the top of the stick to the window or door unit.
When cutting angles on gables, start by cutting a piece of scrap siding or wood to the proper angle then use it to mark each piece. To measure the top row of siding on horizontal eaves, hook the spacer stick on the previous row and measure up to the eave, then rip the siding to width.
Finishing
Painting fiber cement siding.
While fiber cement siding should be painted as soon as possible after installation, factory primed FCS can go as long as six months without painting. Make sure it is clean and dry before painting. Caulk joints and ends first with a high quality latex caulking. Prime bare siding and any exposed cuts then topcoat with 100% acrylic latex paint.
Manufacturer Installation Instructions:
Further Information
- Fiber Cement Siding: A Durable Alternative (article)
- Siding Options for Your Home (video)
This is a continuation of the article How to Install Lap Siding.
Because you’ll be doing a considerable amount of cutting—and accuracy is critical—either buy or rent a power miter saw or a radial-arm saw for the job. You can cut using a circular saw but the going will be slow and less accurate.
Before installing the siding material, you’ll need to attach trim at corners and a level starter strip along the bottom edge of the wall.
If the house’s sheathing is plywood, you can drive nails just about anywhere, but it is best to drive nails into studs to ensure firmness. If the sheathing is fiberboard, gypsum, or other soft material, then you can fasten only to studs.
Consult the manufacturer’s literature and with local builders for the best type of nails to use. Siding nails typically are thin, with small heads. Ring-shank nails hold better than standard nails.
Wherever you will drive a nail less than 3 inches from a board’s end, drill a pilot hole first to prevent cracking the board.
1Install trim and starter strip, as shown in the photo above. To trim an inside corner, nail a piece of 1×1 (which you can rip yourself from a 1x board) or 2×2. At an outside corner, use a 1×3 and a 1×4, or a 1×2 and a 1×3. (The side with the narrower piece will look nearly as wide as the other because of the thickness of the other piece.) Install all trim pieces around windows and doors. At the bottom, install a starter strip supplied by the manufacturer, or install a 1×2. See that the starter board is level. Go all around the house with the starter board to make sure you will come out at the same level when the boards meet at the final corner.
2Install the first siding board at the bottom. Snap a chalk line to guide the top of the bottom board. Cut the board to fit snugly between the trim boards; if it is longer than 6 feet, it is best if you have to slightly bend it to make it fit between trim boards. Align the board with the chalk line and drive nails every 6 inches or so into the starter strip.
12 Inch Smooth Lap Siding
Install the first siding board along the base, overlapping the starter strip.
3Lay out with a story pole. To help with the layout, make a story pole. This is simply a board marked with evenly spaced lines that indicate the reveal you have chosen. Hold the story pole at the correct height at each inside and outside corner and mark the trim boards for the locations of the siding board bottoms.
Create and use a story pole to transfer marks for each siding board at the corners.
Also use the story pole to mark window and door frames.
4Mark trim boards. Again using the story pole, mark the trim pieces around windows and doors. Be sure to hold the pole at the exact same height every time you mark trim boards.
5Install the second siding board. Cut and position the second-from-the-bottom siding board so it aligns with the layout marks you made with the story pole. Check for level to be sure your layout marks are correct. This piece will lap over the bottom board. In certain installations, nails are driven through the bottom of the siding, leaving the heads exposed. In other installations, nails are driven into the upper portion of the boards so they will be hidden by the succeeding piece. Follow the recommendations of your siding manufacturer.
Position and nail the next siding board, placing and spacing nails as recommended by the manufacturer.
6Make butt joints. If a single board will not span all the way between trim pieces, you will need to make a butt joint. Cut the boards so they meet in the middle of a stud. Test to make sure you have a tight fit and then apply caulk to both board ends. Drill pilot holes before driving in the nails.
Join boards end-to-end over a stud location, predrill, caulk the joint, and nail.
7Fit a gable. If you need to cut boards at angles to fit a pitched roof, hold a T bevel tool against the trim piece and the gable to get the angle of the cut. Tighten the wing nut and use the T bevel to mark boards for cutting.
Use a sliding T-bevel to transfer the angle of the roof to the siding boards for making the necessary cuts.