What are the standard thicknesses available for blockboards?

Standard thicknesses are 12, 15, 19, 25, 30, 35, 40, and 50 mm according to Clause 9.1.

What is the difference between BWR and MR grade blockboards?

BWR (Boiling Water Resistant) uses synthetic resin adhesives suited for exposure to water/moisture, while MR (Moisture Resistant) uses urea-formaldehyde adhesives intended for dry indoor applications.

What is the acceptable dimensional tolerance for length and width?

The tolerance for length and width is +6 mm and -0 mm.

What is the permissible moisture content for a standard blockboard?

The moisture content should be between 5% and 15% at the time of testing.

IS 1659

: 2004

Blockboards - Specification

CurrentFrequently UsedSpecificationArchitectural · Timber and Wood

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This standard specifies the requirements, grading, and methods of test for blockboards used in general woodwork, furniture, partitions, and paneling. It categorizes blockboards into two primary grades based on the adhesive used: Boiling Water Resistant (BWR) and Moisture Resistant (MR).

Specifies the requirements for blockboards, including their types, grades, dimensions, physical properties, and testing methods.

Quick Reference Values

Moisture content5% to 15%

Standard thicknesses12, 15, 19, 25, 30, 35, 40, 50 mm

Length and width tolerance+6 mm, -0 mm

Thickness tolerance±5%

Edge straightness tolerance0.2 percent

Squareness tolerance0.2 percent

Practical Notes

Ensure the correct grade of blockboard is selected based on application: BWR for wet areas (kitchens, bathrooms) and MR for dry interior areas.

Always check for delamination or core gaps before use, as excessive gaps can compromise structural integrity and fastener holding capacity.

The blockboards should be properly conditioned to the local moisture content (typically 5% to 15%) before use to prevent warping.