• September 01, 2026
• Shibu Kurian

Sawn Timber Purchase Guidance

How to Avoid Being Short-Charged When Buying Timber

This guide explains how to avoid being short-charged when purchasing sawn timber. Checking only the number and length of the pieces is not sufficient. The width and thickness are equally important, as even a small reduction in either dimension can significantly reduce the total volume of timber supplied. This is particularly important for sawn timber used in cargo securing, industrial packing, cradles, dunnage, skids and other heavy-duty applications.

1. Check the Actual Dimensions

A common timber size used for cargo securing is: 100mm (4 inch) × 100 (4 inch) × 4,000 mm ( 13.2 ft/4 meters)

• Width: 100 mm, approximately 4 inches
• Thickness: 100 mm, approximately 4 inches
• Length: 2,000 mm or 4,000 mm

Please remember:

1 inch = 25.4 mm

Therefore:

4 inches = 101.6 mm

In commercial transactions, 4 × 4-inch timber may be described as 100 × 100 mm.

Your purchase order should clearly state whether the quoted dimensions are nominal sizes or the minimum actual dimensions required.

Recommended specification:
Timber size: 100 × 100 × 4,000 mm, actual dimensions, with a max tolerance of  ±1 mm - ±3 mm , no negative tolerance above this unless approved by the buyer in writing.

2. Do Not Check the Length Alone

Consider 25 pieces of timber measuring 100 × 100 × 4,000 mm.

First, convert the dimensions into metres:

Width: 100 mm ÷ 1,000 = 0.1 m

Thickness: 100 mm ÷ 1,000 = 0.1 m

Length: 4,000 mm ÷ 1,000 = 4 m

The volume of one piece is:

0.1 × 0.1 × 4 = 0.04 m³

The volume of 25 pieces is:

0.04 × 25 = 1.00 m³

Therefore, 25 pieces of 100 × 100 × 4,000 mm timber equal one cubic metre.

Now suppose the supplier invoices you for this size but supplies 75 × 75 × 4,000 mm pieces instead.

Convert the dimensions into metres:

Width: 75 mm ÷ 1,000 = 0.075 m

Thickness: 75 mm ÷ 1,000 = 0.075 m

Length: 4,000 mm ÷ 1,000 = 4 m

The volume of one piece is:

0.075 × 0.075 × 4 = 0.0225 m³

The volume of 25 pieces is:

0.0225 × 25 = 0.5625 m³

Although the quantity and length are correct, you have received only 0.5625 m³ instead of 1 m³.

You have therefore received:

1.0000 − 0.5625 = 0.4375 m³ less timber

0.4375 ÷ 1.0000 × 100 = 43.75% shortage

If one cubic metre costs ₹38,865:

₹38,865 × 0.5625 = ₹21,861.56

₹38,865 − ₹21,861.56 = ₹17,003.44 difference

Therefore, you have paid ₹38,865 but received timber worth only ₹21,861.56 at the same cubic-metre rate.

3. Measure Before Accepting Delivery

Use a measuring tape or vernier calliper to check the width and thickness. Measure randomly selected pieces from different bundles, not only those placed on top.

Take measurements at several points because timber can be tapered or uneven. If different sizes have been supplied, calculate the volume of each size separately.

4. Why Kiln Drying at Source Is Better

Where possible, timber should be kiln-dried at the sawmill soon after cutting.

Kiln drying at source provides better control over the timber’s origin, species, cutting date, initial moisture content and drying schedule. It also reduces exposure to rain, direct sunlight, humidity, insects and uncontrolled storage.

Timber sent to a sales yard before kiln drying may remain exposed for 30–60 days or longer. During this period, green timber can develop:

• Uneven moisture content
• Fungal or blue staining
• Surface and end cracks
• Warping or twisting
• Mould or insect damage

Later kiln drying may reduce the moisture content, but it cannot necessarily reverse damage that has already occurred.

Kiln drying at the sale point can still be acceptable when carried out by a properly equipped facility. Ask for:

• Initial and final moisture readings
• Kiln-drying schedule and treatment dates
• Batch identification
• Kiln calibration records
• Final inspection report
• Details of storage before and after drying

Even correctly kiln-dried timber can absorb moisture again during transport or outdoor storage. Always check the moisture content and physical condition when the timber is delivered.

5. Understand Kiln Drying and ISPM 15

Kiln drying and ISPM 15 treatment are often confused, but they have different purposes.

Kiln Drying

Kiln drying primarily reduces the timber’s moisture content. It helps improve dimensional stability and reduce shrinkage, warping, splitting and moisture-related deterioration.

The required final moisture content should be clearly stated in the purchase order.

ISPM 15 Treatment

ISPM 15 is an international phytosanitary standard for wooden packaging used in international trade, including pallets, crates, packing blocks and dunnage.

Its purpose is to reduce the international spread of plant pests—not to guarantee low moisture content or structural quality.

Under conventional ISPM 15 heat treatment, the entire timber profile, including its core, must reach at least:

56°C for 30 continuous minutes

Compliant timber must be treated under an authorized system and carry the appropriate IPPC mark.

Likewise, ISPM 15-treated timber is not necessarily adequately kiln-dried. The timber may satisfy the phytosanitary requirement while still containing more moisture than the buyer requires.

Timber-Buying Checklist

Before accepting a timber delivery, verify:

• Actual width, thickness and length
• Number of pieces and calculated cubic volume
• Permitted dimensional tolerance
• Kiln-drying certificate and batch details
• ISPM 15 treatment and IPPC mark, where required
• Proper storage and protection from the weather
• Measurements and discrepancies recorded on the delivery note

Final Advice

Never purchase timber based only on appearance, length or piece count. Always calculate:

Width × Thickness × Length × Quantity = Total Timber Volume

A reduction from 100 × 100 mm to 75 × 75 mm may not appear substantial, but it means receiving 43.75% less timber.