Floor joists - Timber – cost per m² – UK 2026 Rate Guide

Budget rate for supply & lay · typical budget rate before your adjustments

Floor joists - Timber

per m² · supply & lay

£61 – £149 / m²

What is it

Structural timber members installed at regular centres to support floor decking and transfer imposed and dead loads to walls or beams.

Rate guide

Standard C24 solid timber joists, 47 × 195 mm at 400–450 mm centres£61 – £83/m²

Deeper C24 solid timber joists, 47 × 220–245 mm£72 – £99/m²

Treated solid timber joists in higher-risk locations£77 – £110/m²

Engineered timber I-joists with standard accessories£83 – £116/m²

Metal-web open joists for coordinated services£105 – £149/m²

Labour output

Repetitive open floor plate with clear bearing lines35–50 m²/day

Typical dwelling floors with standard openings and trimming25–35 m²/day

Irregular layout with multiple trimmers and service zones15–25 m²/day

Broken-up work, restricted access or occupied refurbishment8–15 m²/day

Key rate adjusters

Joist depth

Increasing the section for longer spans or higher loads typically adds £8–£25/m².

Centres

Reducing spacing from 450 mm to 400 mm can increase the installed rate by approximately 8–15%.

Openings

Stairwells, chimneys and service penetrations requiring doubled joists and trimmers can add £10–£30/m² locally.

Metalwork

Extensive hangers, straps, restraint and proprietary connections can increase the rate by £5–£15/m².

Access

Crane lifts, scaffold handling or restricted internal distribution can add 10–25% to labour and plant costs.

Performance

Preservative treatment, fire protection or enhanced acoustic detailing can add £8–£30/m² depending on specification.

Quantity surveyor insights

Waste and buildability: Allow around 5–10% timber waste where lengths, trimming and openings are not optimised; coordinated joist layouts and standardised spans materially reduce cutting, doubled members and site labour.
Scope and procurement: Confirm whether the package includes hangers, restraint straps, blocking, strutting, rim boards, trimming members and design responsibility, as these are frequent scope gaps. Engineered joists should be ordered against a coordinated fabrication layout because late service or opening changes can create redesign costs and programme delay.

Estimate Anything AI answer · indicative budget rates · updated 31 August 2026