Quality.
    Minimum
    England

    Lateral restraint for timber floors

    90 mm

    Timber floors can provide lateral restraint to masonry walls if joists have a minimum 90mm bearing onto the wall

    Timber floors can provide lateral restraint to masonry walls if joists have a minimum 90mm bearing onto the wall. If this condition is not met, or additional restraint is required, restraint straps with a minimum 30mm x 5mm cross-section, or proprietary restraint type joist hangers complying with BS EN 845-1, must be used.

    Basis in regulation

    How to check it on site

    Verify joist bearing width or the correct installation and specification of restraint straps or hangers where joist bearing is insufficient.

    Common failure

    Insufficient joist bearing or incorrect specification/installation of restraint straps can lead to inadequate lateral support for walls.

    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

    Light steel floor joist spacing and design

    600 mm

    Light steel floor joists should typically be installed at a maximum spacing of 600mm centre-to-centre, although wider spacings may be permitted if specifically engineered

    Minimum

    Floor joist end bearing on masonry

    90 mm

    Bearing directly onto masonry or a wall plate; joist hangers follow the hanger manufacturer's seating instead

    Minimum

    Strutting rows by joist span

    One row over 2.5 m span; two rows over 4.5 m

    Herringbone or solid strutting, tight between joists and restrained at the ends

    Maximum

    Floor deck fixing centres

    300 mm at supported edges, 500 mm at intermediate joists

    Boards laid with the long edge across the joists and joints staggered

    Minimum

    Lateral restraint for concrete floors

    90 mm

    Concrete floors offer lateral restraint to walls when they bear a minimum of 90mm onto the masonry

    Minimum

    Joist bearing and pointing

    90 mm

    Timber joists require a minimum bearing surface, typically 90mm, on supporting masonry or timber to ensure stable load transfer

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