- Exposed Face Width vs. Nominal Width: Standard 1x6 shiplap boards have a nominal width of 6 inches, actual width of 5.5 inches, but only an exposed face width of 5.25 inches due to the rabbet overlap. Always base your calculations on the exposed face width.
- Nickel Gap Spacing: While true shiplap self-spaces via its overlapping rabbets, if you are custom-routing or using tongue-and-groove boards, use a U.S. nickel coin (approximately 1/8″ or 3mm gap) as a spacing gauge.
- Wood Acclimation: Store lumber in the installation room for at least 72 hours before nailing. This prevents planks from shrinking (leaving gaps) or expanding (causing buckling) after installation.
- Fastening into Studs: Always secure shiplap by nailing directly into vertical wall studs (typically spaced 16″ or 24″ on center) using 15-gauge or 16-gauge finish nails.
The Comprehensive Guide to Planning, Estimating, and Installing DIY Shiplap
Shiplap cladding is one of the most effective ways to introduce depth, texture, and character to flat walls and ceilings. Originally developed as an exterior structural siding to protect barns and seaside cottages from high winds and moisture, shiplap has transition into a modern farmhouse and contemporary interior design staple. However, when planning a shiplap project, the key to success lies in careful planning and wood estimation.
Unlike drywall, wood shiplap relies on overlapping joint geometry. This means you cannot simply calculate the raw square footage of a room and purchase that amount of wood. You must account for overlapping rabbets, rip cuts around electrical outlets, window and door deductions, and wood acclimation shrinkage. In this guide, we break down shiplap dimensions, layout math, material types, and step-by-step installation instructions for a professional-grade finish.
The Math Behind Shiplap: Nominal vs. Exposed Face Width
The most common source of material shortages in DIY shiplap installations is using "nominal" widths. Lumber is classified by its size before it is planed and milled. For instance, a 1x6 shiplap board is not 6 inches wide:
- Nominal vs. Actual: The milling process reduces a nominal 1x6 board to an actual physical width of 5.5 inches.
- The Overlap Rabbet: Shiplap boards overlap at their edges using a rabbet joint. This overlap (usually 1/4 inch to 3/8 inch) is hidden from view once the boards are interlocked.
- Exposed Face Width: This is the visible width that actually covers the wall. For a standard 1x6 shiplap board, the exposed face is exactly 5.25 inches.
Using 6 inches instead of 5.25 inches for your calculations will result in buying 14.3% too little lumber! Our calculator avoids this error by using actual exposed widths to estimate row runs and plank counts.
Styling Options: Horizontal, Vertical, or Ceiling Cladding?
How you arrange the shiplap planks dramatically impacts the perception of space in your home:
- Horizontal Layout: The traditional, classic look. Horizontal lines guide the eye side-to-side, making narrow rooms, hallways, and powder rooms feel wider and more spacious.
- Vertical Layout: A modern, contemporary design statement. Vertical planks lead the eye upward toward the ceiling, creating an illusion of height that makes low-ceilinged rooms feel loftier. It is ideal for entryways, mudrooms, and behind bathroom vanities.
- Ceiling Cladding: Cladding a ceiling in shiplap is a popular way to cover cracked plaster or drywall, while bringing architectural warmth to the space. It can be run parallel to the room's longest wall or diagonally for a custom accent.
Material Options: MDF, Pine, Cedar, or PVC?
Selecting the right shiplap board material depends on your room's environment, budget, and desired paint finish:
- MDF (Medium-Density Fiberboard): The cheapest and most stable option for dry rooms. MDF planks are perfectly uniform, smooth, and do not warp, cup, or feature knots. It is ideal for painted accent walls. Do not use MDF in bathrooms or damp basements, as it swells and disintegrates when exposed to moisture.
- Pre-Primed Pine: Real wood boards that come pre-primed. They are easy to install, dent-resistant, and have a natural wood texture under paint. Poplar is also a premium choice for painting.
- Solid Cedar or Cypress: Highly moisture-resistant, making them the best option for bathrooms, saunas, and covered outdoor patios. Cedar looks beautiful stained or clear-coated to highlight its rich red and brown colors.
- PVC / Vinyl Shiplap: 100% waterproof synthetic paneling. It is perfect for direct wet areas like showers, tub surrounds, or high-humidity basements.
Essential Step: Wood Acclimation
Real wood shiplap expands and contracts in response to indoor humidity. When you bring lumber home from the store, **do not install it immediately.** Stack the boards flat inside the room where they will be installed for at least 72 hours (5-7 days for hardwoods). This allows the moisture content of the wood to equilibrate with your home's HVAC environment, preventing the boards from shrinking (leaving gaps) or expanding (causing buckling and cupping) after installation.
Step-by-Step Installation Manual
1. Find and Mark Studs
Use a stud finder to locate wall studs and draw a vertical pencil line down the center of each stud. For horizontal shiplap, you will nail directly into these studs. For vertical layouts, nail into the top and bottom plates, or install horizontal furring strips (1x2 wood grids) spaced 16 inches apart over the drywall to provide a solid nailing surface.
2. Align the First Planks
Walls and floors are rarely perfectly level. Never rely on the floor line to start your first row. Instead, use a laser level or a 4-foot bubble level to draw a level line near the bottom of the wall. Align the top edge of your first shiplap board with this line, leaving a 1/8-inch expansion gap at the bottom floor trim. Nail it securely.
3. Spacing the Joints (The Nickel Gap)
Standard shiplap is famous for its "nickel gap"—a uniform 1/8-inch gap between planks. Many modern tongue-and-groove products feature self-spacing profiles. If yours does not, place real U.S. nickels or plastic tile spacers between rows before securing them.
4. Stagger Your Seams
If your wall is wider than your board length (e.g. a 16-foot wall using 12-foot boards), you must butt joints together. Stagger these butt joints across different rows so they do not line up vertically. Keep joints at least 24 inches apart from row to row to maintain structural strength and a clean visual flow.