What is a smetplank (handrail backing board and gutter board)?
A smetplank is a Dutch term for a board that protects a wall from dirt or water. It has two meanings: a board fixed to the wall that carries the brackets of a stair handrail, and a board under the roof gutter that stops water from the gutter running down the facade. The word comes from the Dutch smetten, to soil. There is no single fixed English term; staircase wallboard or handrail backing board come closest for the first meaning.
Meaning 1: board behind the handrail
Also called a leuningplank. The board runs along the wall parallel to the handrail. The handrail brackets are screwed to the board rather than directly into plaster or masonry. Hands sliding along the rail touch the board instead of the wall, and a painted board is much easier to wipe clean than plaster.
Meaning 2: board under the gutter
Here the board closes the gap between the underside of the gutter and the masonry of the facade. It gives a neat finish and protects the wall from overflowing or dripping water. With plastic gutters, Dutch manufacturers often supply the board in the same material, so gutter, board and any gutter blocks form an (almost) seamless unit.
Application
- Stairs: fix it firmly. The handrail has to take load. Fix the board with plugs into masonry, or into studs or noggins behind a lightweight wall, not into plasterboard alone.
- Stairs: follow the string. Keep the board parallel to the handrail and finish the ends neatly.
- Stairs: choose a washable finish, such as gloss or satin paint.
- Gutter: keep the fall towards the outlet, so no standing water pushes against the board.
- Gutter: detail the junction with the facade as the supplier specifies, including expansion and ventilation gaps.
Common mistake: leaving a timber board under the gutter poorly finished or unmaintained. It then rots, while it was meant to protect the facade.
Related terms
- Skirting board
- Gutter
- Gutter block
- Fascia board
- Eaves
- Open string stair
Want to know more about building terms? Visit our knowledge base at fredsdiyplans.com.