Accessible threshold upstand

15 mm maximum total upstand, chamfered or pencil-rounded above 5 mm

Principal entrance to a dwelling designed to be accessible

Minimum

Clear opening width of an internal door

750 mm from a corridor at least 900 mm wide; 775 mm from a 825 mm corridor; 900 mm from a 750 mm corridor

Internal doorway on the entrance storey of a dwelling

Tolerance

Flatness of a finished plasterboard surface

Within 3 mm under a 1.8 m straightedge

Measured on the finished surface in any direction, away from internal corners

Maximum

Plasterboard fixing centres

200 mm to ceilings, 300 mm to walls, and 150 mm at board ends

Fixings kept at least 10 mm from cut edges and 13 mm from bound edges

Maximum

Timber moisture content before closing up

20 %

Measured with a calibrated meter at several points, including sole plates and the base of studs

All critical dimensions · All topics

These entries are our own editorial summaries of publicly available regulation. They are not building control approval, a warranty determination, or a substitute for the full source document.

Tolerances and setting out — critical dimensions

Accessible threshold upstand

Clear opening width of an internal door

Flatness of a finished plasterboard surface

Plasterboard fixing centres

Timber moisture content before closing up