How to Inspect a Timber Batch Before Accepting Delivery

Why Inspection at Delivery Matters

Once timber is installed — nailed into a roof structure, built into a wall frame, cut into furniture components — problems discovered after the fact are expensive to resolve. The correct time to identify and reject sub-standard timber is at delivery, before it is unloaded and accepted. Once you have signed for a delivery and the lorry has left, your options for remedy are significantly more difficult to exercise.

A timber inspection does not need to be slow or complicated. With a moisture meter, a basic knowledge of what to look for, and the relevant treatment documentation in hand, an experienced buyer can assess a typical delivery in 20–30 minutes and make a confident accept-or-reject decision.

Step 1: Check Documentation Before Inspecting the Timber

Before touching the timber, verify the documentation. For treated structural timber you need: the treatment batch record (species, cross-section, pre-treatment MC, VPI cycle parameters, retention, treatment date, treating facility name and IPPC registration number). For export pallets, also check ISPM 15 compliance documentation.

If documentation is absent or incomplete, stop. Treatment that is not documented either did not happen or cannot be verified. Request the records from the supplier before proceeding. Accepting without treatment records means you have no basis for a warranty claim if problems emerge later.

Step 2: Check Moisture Content

Select boards from different positions in the stack — top, middle, bottom, and from both ends. Use a calibrated moisture meter with the correct species setting. Take at least three readings per board: at both ends and in the middle, on both faces.

Compare to the specified MC. For structural timber, accept deviations of ±2–3% as normal batch variation. A batch where the majority of readings are 5% or more above the stated target MC has not been dried to specification — reject or arrange re-drying before use. Flag any board where the face reading is much lower than the edge reading, which may indicate a dry surface over a wet core.

• Set the species correction before taking any readings
• Sample from multiple stack positions — not just the accessible top layer
• Take readings on both faces and both ends of each sampled board
• For thick sections: use deep probes to check core MC
• Batch fails if majority of readings are more than 3% above specified MC

Step 3: Inspect for Visible Defects

Walk the length of the stack and look for: significant warp (boards visibly bowed, cupped, or twisted), large checking (cracks wider than 2–3mm or penetrating more than a quarter of the thickness), honeycombing on cut ends (internal voids visible in the cross-section), end splitting extending more than 150mm, and blue stain or surface mould if appearance matters.

Pull 5–10% of boards and inspect both faces and both ends. For structural timber, check end grain on sampled boards for ring shakes (separations along the growth ring boundary) and heart shakes (radial cracks from the pith).

Step 4: Verify Dimensions and Count

Measure actual thickness and width at multiple points along sampled boards. Shrinkage from drying results in actual dimensions slightly below green-sawn nominal — significant undersizing may indicate the timber was cut below nominal or a higher-shrinkage species has been substituted. Count pieces and verify against the delivery note.

Step 5: Accept or Reject

Accept if: documentation is complete, MC is within 3% of specification on the majority of sampled pieces, visible degrade is within grade limits, and dimensions are as ordered.

Reject or renegotiate if: documentation is absent, MC is consistently more than 3% above specification, significant structural defects (ring shake, honeycombing, severe case hardening) appear in more than 10–15% of sampled pieces, or dimensions are systematically short. Document any rejection in writing before the lorry leaves.