What are the standard types of hardboards classified by this IS code?

The code classifies them into three types: Standard Hardboard, Tempered Hardboard, and Medium Hardboard (Clause 5).

What is the permissible moisture content for fibre hardboards?

The moisture content should be between 5 percent and 11 percent (Table 2).

How does tempered hardboard differ from standard hardboard in terms of density?

Standard hardboard has a minimum density of 800 kg/m3, whereas tempered hardboard has a higher minimum density of 900 kg/m3.

IS 1658

: 2006

Fibre Hardboards - Specification

CurrentSpecializedSpecificationArchitectural · Timber and Wood

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This standard specifies the requirements, grades, and testing methods for fibre hardboards (standard, tempered, and medium) primarily used for interior paneling, partitioning, and furniture manufacturing.

Lays down the requirements for fibre hardboards, including their classification, dimensions, physical properties, and testing methods.

Quick Reference Values

moisture content range5 to 11 %

density standard hardboard>= 800 kg/m3

density tempered hardboard>= 900 kg/m3

density medium hardboard350 to 800 kg/m3

standard thicknesses3, 4.5, 6, 9, 12 mm

tolerance thickness upto 6mm± 0.3 mm

max water absorption 24h standard 3mm30 %

Practical Notes

Hardboards are highly susceptible to moisture and swelling; edges should be properly sealed if used in potentially damp interior areas.

Tempered hardboards undergo special treatment with drying oils or resins to improve strength and water resistance, making them better suited for heavier applications.

Always refer to IS 2380 for the specific testing procedures (moisture content, density, bending strength) referenced in this code.