What is a foot brace?
A foot brace is an inclined piece of timber at the foot of a roof truss that connects the rafter (the sloping roof member) to the attic or floor joist. Often it is a short, sloping post resembling an ashlar post. Sometimes it is a triangular, rounded block of wood. In Dutch it is called a voetschoor; the English term down brace is also used.
Function
Together with the rafter and the floor joist, the foot brace forms a triangle. A triangle does not deform, so the connection between roof and floor becomes rigid. This increases the stability of the roof in the transverse direction: the trusses are less likely to rack or push outwards.
This was especially important in historic timber-frame construction, where the timberwork itself had to provide all the stability. A characteristic form of foot braces occurs in the timber-frame buildings of North Holland, for example in the Zaan region. An ashlar post or a curved brace is often used for the same purpose.
Recognising it
- The foot brace stands at an angle between the floor joist and the rafter, close to the eaves.
- It is often hidden behind a knee wall.
- In old buildings it is sometimes fixed with a mortise and tenon joint or wooden pegs.
Tips when renovating
- Do not simply remove it: when enlarging the attic or fitting a dormer, foot braces are sometimes found in the way. They can be essential for the stability of the roof. Have a structural engineer assess whether and how they can be replaced.
- Check for rot: at the eaves, leaking water can go unnoticed for a long time. Probe the timber with an awl or screwdriver; soft wood indicates rot.
- Check the joints: loose pegs or dried-out joints reduce its effect. Repair them before finishing the attic.
Related terms
- Brace
- Roof truss
- Ashlar post
- Curved brace
- Knee wall
- Eaves
- Timber frame construction
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