Shiplap Joint
A shiplap joint is an edge profile where each board has a rabbet (step) cut on opposite faces of its two edges, so adjacent boards overlap when installed. Unlike tongue and groove, which interlocks, shiplap simply overlaps. Shiplap is popular for siding, wall paneling, and exterior applications because it sheds water at the joints.
In-Depth Explanation
Shiplap is one of the simplest and oldest edge joint profiles used in wood construction. The rabbeted edges overlap to create a tight joint that allows boards to expand and contract with seasonal moisture changes without opening gaps. For exterior applications like siding and outbuilding walls, shiplap's overlapping profile naturally directs water outward away from the wall assembly, making it more weather-resistant than butt-joined boards. This water-shedding ability made shiplap the preferred cladding for barns, sheds, and rural buildings for centuries. In recent years, shiplap has experienced a dramatic resurgence as an interior design element, popularized by home renovation shows. Interior shiplap paneling creates a clean, horizontal-lined aesthetic with subtle shadow lines at each joint. For interior use, the boards are typically 1x6 or 1x8 pine, cedar, or MDF, installed horizontally with a consistent reveal (the visible gap or shadow line) at each joint. Shiplap is easier to install than T&G because the boards don't need to be angled into place — they simply slide together from the face.
Usage Example
The designer specified shiplap pine paneling for the mudroom walls, choosing a 1/8-inch reveal at each joint for the clean, modern farmhouse look the client wanted.