What is the minimum ground clearance required for stacking timber during air seasoning?

The foundation supporting the stack should be at least 300 mm above the ground level to allow adequate air circulation.

How does the code classify kiln drying schedules?

Kiln seasoning schedules are classified into seven categories (Schedule I to VII) based on how refractory (resistant to drying) the specific timber species is.

What is the recommended width for a timber stack in air seasoning?

The width of the stack should generally be kept between 1.5 m and 2.0 m to ensure uniform drying across the entire width.

How can seasoning defects be minimized during kiln drying?

By strictly following the temperature and humidity stages prescribed in the appropriate kiln schedule for the specific timber species and utilizing periodic conditioning treatments.

IS 1141

: 1993

Seasoning of timber- Code of practice

CurrentSpecializedCode of PracticeMaterials Science · Timber and Timber Stores

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This code provides guidelines for the proper seasoning of timber using air-drying and kiln-drying methods. It specifies kiln drying schedules based on the refractoriness of different timber species to reduce moisture content safely, preventing defects like warping, splitting, and fungal decay.

Seasoning of timber- Code of practice

Quick Reference Values

Minimum ground clearance for timber stacks (air seasoning)300 mm

Recommended width of timber stack (air seasoning)1.5 m to 2.0 m

Minimum distance between adjacent stacks600 mm

Thickness of crossers used between timber layers25 mm to 40 mm

Distance between crossers along the length of the stack450 mm to 600 mm

Practical Notes

Timber species are classified into highly refractory, moderately refractory, and non-refractory categories; always use the correct kiln schedule (Schedule I to VII) corresponding to the species.

During air seasoning, ensuring a minimum of 300 mm ground clearance and using proper crossers is critical for air circulation and preventing bottom-layer rot.

Always check IS 287 alongside this code to determine the target moisture content required for the specific end-use and climatic zone in India.