Bottom plate
The bottom plate is the horizontal member fixed to the slab that studs stand on, and the first link in the tie-down chain. How it's fixed under AS 1684.
Ask Chalkline about this →A bottom plate is the horizontal framing member fixed to the floor or slab that the wall studs stand on. It forms the base of a stud wall (the top plate caps the studs at the other end) and is also called the sole plate.
The bottom plate is the first link in the tie-down chain that resists wind uplift. It is fixed down to the slab with cast-in bolts, masonry anchors, or powder-actuated fasteners at the spacing set in the AS 1684 tie-down schedule for the site wind classification. From there the chain runs up: bottom plate to slab, stud to bottom plate, stud to top plate, and on to the roof.
Where the plate sits on or near a slab it is usually treated timber (H2 or as specified) for termite and decay resistance.
Common defect: bottom-plate fixings missed, at the wrong centres, or under-strength anchors drilled into a cured slab. This breaks the tie-down chain, and the uplift resistance of every level above is lost.
Also known as: sole plate.
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Last updated: 2026-05-24. Verified: 2026-05-24. Quarterly review for currency.