Boarding (Dutch: beschieten) is a construction technique that involves fixing planks, boards, or sheet materials onto a load-bearing timber structure — such as a roof rafter assembly, wall frame, or ceiling structure. The resulting boarding layer serves as a substrate for further layers of insulation, underlay, or roofing material. A roof with boards nailed to the rafters is known as a “boarded roof” or “close-boarded roof”.
The technique is fundamental to traditional carpentry and has been used in building construction for centuries. While the concept is straightforward, skilled execution is essential: the boards must be fixed tightly and level to provide a sound base for subsequent layers. Gaps, warps, or poorly fixed boards can lead to problems with insulation performance, water ingress, or structural weakness.
Applications
Boarding is used on various parts of a building:
- Roof constructions (close-boarded roof) — Timber planks or plywood sheets are nailed or screwed to the rafters and purlins. This boarding layer forms the base onto which roof insulation, roofing felt or breathable membrane, and tiles or slates are fixed. A boarded roof provides extra rigidity and a neater finish when viewed from the interior.
- Walls and facades — In timber-frame construction, the wall studs are boarded with OSB, plywood, or other sheet materials. This gives the wall racking resistance (diaphragm action) and forms the substrate for insulation and interior or exterior finishing.
- Ceilings — Joist structures are boarded from below with planks or plasterboard to create a flat ceiling surface.
- Floors — In traditional timber floors, the joist layer is boarded from above with floorboards or sheet material to create the walking surface.
Common boarding materials
- Softwood planks (spruce or pine) — Traditionally the most common option, available as tongue-and-groove boards for a seamless joint.
- Plywood — A strong sheet material that covers larger areas in a single piece with good structural performance.
- OSB (Oriented Strand Board) — Widely used in timber-frame construction due to its excellent strength-to-cost ratio.
- MDF or hardboard — Primarily used for interior finishing and ceiling linings where structural loads are minimal.
Related terms
- Close-boarded roof
- Roof decking
- Timber-frame construction
- Purlins
- Rafters
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