Wall tie spacing in a standard cavity wall

900 mm horizontally, 450 mm vertically (2.5 ties per square metre)

Masonry cavity wall, cavity width up to 100 mm, wall height up to 15 m

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Maximum horizontal and vertical spacing for wall ties in masonry cavity walls up to 100 mm cavity width.

Ties at 900mm horizontal and 450mm vertical centres, staggered row to row so no tie sits directly above another.Original ProPlot drawing, not to scale. Geometry verified against Approved Document A, structure.

Basis in regulation

Part A
Approved Document A
Read the source

How to check it on site

Count ties per square metre on each lift before the cavity is closed. Check ties are level or fall slightly to the outer leaf and that drip features point downwards.

Common failure

Ties omitted at the top of a lift, sloping towards the inner leaf, or mortar-fouled so water tracks across the cavity.

Effective from 20 August 2026. Last updated 23 August 2026. This is our editorial summary of publicly available regulation, not building control approval or a warranty determination.

Related dimensions at this stage

Maximum

Wall tie spacing at reveals and movement joints

Additional ties at 300 mm vertical centres within 225 mm of the opening

Within 225 mm of an unbonded vertical edge — reveals, movement joints, wall ends

Maximum

Cavity wall tie vertical spacing

450 mm

vertical spacing of cavity wall ties does not exceed 450mm.

Maximum

Cavity wall tie horizontal spacing (partial-fill insulation)

600 mm

horizontal tie spacing for partial-fill insulated cavities does not exceed 600mm.

Maximum

Cavity wall tie horizontal spacing (full-fill insulation)

900 mm

For cavity walls incorporating full-fill insulation, wall ties must be placed at maximum 900mm horizontal centres

Maximum

Lowest fixing position for straps

150 mm

For any structural strap, the lowest fixing into the masonry or supporting structure must be positioned no more than 150mm from the bottom of the strap

Minimum

Chimney wall thickness and construction

100 mm

The minimum wall thickness for block, brick, or stone chimneys, excluding flue lining, is typically 100mm