Timber Grading

New Timber in sawmills.

Old timber in-situ.


Knot being measured during grading

Knot being measured during grading

Timber Inspection Services (Australia wide)

  • Timber Inspection provides an independent grading service to ensure you get the species or species group and grade that was specified. We have inspectors within the Sydney region and on the North and South Coasts.
  • We can inspect timber at sawmills, warehouses or onsite. If you require our services at sawmills or warehouses please ensure you let your supplier know at the time of ordering. On top of our fees, they may need to make allowance for additional handling. We will only issue a certificate of compliance where we have been able to inspect all surfaces of each piece.
  • Our services are not expensive but removing and replacing defective timber may be. Other than travel our costs we charge on volume for timber inspected at sawmills etc or on a quotation basis for timber in-situ. Inspections at suppliers(sawmillers, importers) premises can usually be organised through the supplier. If they are not interested or tell you we can’t be contacted try another supplier be wary of those who do not wish a third party to assess there quality. Many sawmills are quite happy for us to grade there timber. We are usually available within a few days if not that day or the next day. I most instances it takes a few days for your order to be processed so if notified a few days in advance the availability issues are usually averted.If you have any issues in acquiring our services ring 0429 646 112.
  • We also grade timber in-situ. A written report is usually supplied with this service as the limitations of providing this service need to be described. Engineers use this service to ensure that the timber has not been damaged during its previous life and to ensure that the structure is adequate to carry the loads required in the refurbished structure. We also carry out in-situ inspections on bridges and wharves.
  • If you have any enquiries regarding this service please call Richard Forrester on 0429 646 112 or submit a contact form.

Timber is graded to determine its structural properties and/or its acceptable visual appearance.

There are 2 methods used to grade timber, mechanical grading and visual grading. Mechanical grading is either a bending tests or a sonic test. The Australian Standards for mechanical grading are AS 1748 series. Mechanical grading is not discussed below.

Structural Grading

  • There are Australian Standards for structural visual grading. They are AS 2082 (hardwoods), AS 2858 (softwoods) and AS 3818 series for hardwood heavy engineering products such as railway timber, bridge, wharf timber, poles and crossarms.
  • To give timber a visual structural grade first you have to know the species. The species are divided into strength groups. S1 (unseasoned) or SD1 (seasoned) to S6 or SD6. The strength groups S1 or SD1 being the strongest.
  • The second step is to allocate a structural grade. To allocate a structural grade the timber has to be visually inspected for characteristics such as knots, splits, missing timber, mechanical damage etc. There are 4 structural grades for hardwoods and 5 for softwoods. Structural grade 1 having the smaller characteristics. The AS 3818 series are divided into select and standard grade, which are similar to structural grade 1 and structural grade 2 in AS 2082.
  • When you have determined the strength and the structural grade you can nominate a visual stress grade. For example timber which is S2 and structural grade 1 makes a visual stress grade of F22. Timber which does not meet the minimum grade should not be used for structural purposes.
  • Engineers can use the timbers size along with the stress grade to determine what loads the timber will carry.

Visual Grading

  • Visual grading is used for products like floorboards, domestic decking, lining boards and weatherboards. The Australian Standards used to visual grade these timber products are AS 2796 series (hardwoods), AS 4785 series (softwoods) and AS 1810 Cypress.
  • AS 2796 (Hardwoods) uses the terms Select Grade, Medium Feature Grade and High Feature Grade select grade being that with the least and smallest features.
  • AS 4758 (softwoods) uses the terms Clear, Appearance, Select, Standard and Utility. AS 1810 (cypress) uses Grade 1 and Grade 2.
  • Australian Standards are not compulsory unless called up under legislation. Many producers use their own grading rules. Consumers should make sure they understand the grade before purchasing. If you want the product to meet the requirements of an Australian Standard, ensure you put that in writing when you order the timber.

Comments

  • It should be noted that timber should not fall below the grade specified. Timber that is supplied may however be a higher grade than that specified.
  • Consideration also needs to be given to specifying timber that has sufficient durability. Timber in the ground or in contact with the ground should be in-ground durability class 1 or 2. Where it is not in-ground durability class 1 or 2 it should be preservative treated to H4 or H5. H4 is for soil conditions with moderate wetting and H5 for severe wetting or saturation or for structural timber that is difficult to replace.
  • Timber that is above the ground and subject to the ingress of moisture should be above-ground durability class 1. If the timber is not above-ground durability class 1 it should be treated to a minimum of H3. Sapwood unless treated is not durable and will decay much quicker than durable heartwood. Timber submerged in a marine environment should be able to resist marine timber pests (Turpentine) or be treated to H6.
  • Timber is not a mass produced product where each piece is exactly identical. It is a natural product where each piece can have characteristics that can vary considerably even with the same species or even the same tree. Timber has exceptional performance in a wide range of applications, provided the correct species and grade is used for the particular situation. Timber that is protected from the ingress of moisture in most cases does not need to be durable.
Pack of railway sleepers

Example Timber Inspection quality mark

Inspecting roof timber in-situ

Inspecting roof timber in-situ

Crossarms prior to inspection

Crossarms prior to inspection

Sleepers packed after inspection

Sleepers packed after inspection

Grading floor joists in-situ. Note Mortise and Tenon

Grading floor joists in-situ. Note Mortise and Tenon

Split plastic wood. Did not work good in this application.

Split plastic wood. Did not work good in this application.