IS 287 : 2022Code of Practice for Design of Timber Structures

IS 287:2022 gives recommendations for the limits of moisture content of timber and timber products for various end uses in India — the permissible moisture content (MC) by climatic zone and application (joinery, doors/windows, flooring, furniture, structural). Getting timber MC right is the single biggest determinant of whether timber joinery warps, shrinks, splits or stays stable in service.

*(Note: the code-database title for this entry currently reads 'Code of Practice for Design of Timber Structures'; IS 287's established subject is permissible moisture content of timber — structural design of timber is IS 883. The discrepancy has been flagged for correction; this note addresses IS 287's actual scope.)*

It is read with the timber stack:

• IS 883 — design of structural timber in buildings · IS 1708 — testing small clear timber specimens
• IS 1141 — seasoning of timber · IS 4021 — timber door/window frames · IS 1003 — timber door shutters
• IS 710 / IS 303 — plywood (companion timber products)

Timber moves with moisture: it shrinks/swells as MC changes until it reaches equilibrium moisture content (EMC) with the surrounding air. IS 287 zones India by humidity and gives the permissible MC at the time of fixing so the timber is *already near its in-service EMC* and therefore stays dimensionally stable:

• Climatic zones (humid coastal vs dry interior etc.) — each has different EMC, so different permissible MC limits
• End-use limits: structural members, exterior joinery, interior joinery/furniture, flooring — each with a tighter or looser MC band
• Typically interior joinery/furniture demands the lowest MC (driest, most stable), structural the highest tolerance
• Read with IS 1141 (seasoning) — the timber must be *seasoned (air/kiln) to the IS 287 limit* before fabrication, and protected from re-absorbing moisture before fixing

Fix timber wetter than its zone/end-use limit and it *will* shrink, gap, warp and split after installation — guaranteed, not probabilistic.

Scenario: seasoned hardwood for interior door shutters & furniture in a dry-interior city.

Step 1 — zone & end-use: identify the IS 287 climatic zone for the site and the end use (interior joinery — the tightest MC band).

Step 2 — target MC: read the permissible MC limit for that zone + end use (interior joinery in a dry zone is a low single-digit-to-low-teens % band — well below freshly-sawn timber).

Step 3 — verify on delivery: measure MC with a calibrated moisture meter at several depths/pieces; reject the lot if above the IS 287 limit (it is *not* seasoned enough — fabricating it now means callbacks).

Step 4 — protect: store the accepted seasoned timber dry and fabricate/fix promptly so it doesn't re-absorb moisture above the limit before installation.

Step 5 — outcome: timber fixed at its zone-EMC stays stable; the recurring 'new doors jammed/shrunk in 3 months' complaint is almost always timber fixed above its IS 287 MC limit.

1. Specifying 'seasoned timber' with no MC limit. 'Seasoned' is meaningless without the IS 287 zone/end-use MC number — and unverified.

2. Not measuring MC on delivery. A moisture meter check takes minutes; skipping it is why warped/split joinery appears months later.

3. Ignoring the climatic zone. The same MC that's fine in humid Mumbai is too wet for dry Delhi/Jaipur interiors — the limit is zone-dependent.

4. Fabricating then letting timber re-wet before fixing. Correctly seasoned timber left exposed re-absorbs moisture and moves anyway — protect it through to installation.

5. Same MC for structural and fine joinery. Interior furniture/joinery needs a much lower MC than structural members; one blanket figure fails one or the other.

• IS 883 — code of practice for design of structural timber in buildings
• IS 1141 — code of practice for seasoning of timber
• IS 1708 — methods of testing small clear specimens of timber
• IS 4021 — timber door/window/ventilator frames · IS 1003 — timber door shutters
• IS 303 / IS 710 — plywood (companion products)
• IS 401 — preservation of timber

IS 287 is reaffirmed and remains the controlling reference for timber moisture content; the page/database title for this entry appears mis-described as a *structural design* code — IS 287's real subject is permissible moisture content by zone and end use (structural design = IS 883), and this is flagged for a metadata fix. Rely on the moisture-content scope.

The practitioner reality: almost every timber joinery failure in service — jammed doors, gapped flooring, split panels, warped shutters — is a moisture-content failure, not a timber-species failure. The whole defence is procedural and cheap: specify the IS 287 zone/end-use MC limit explicitly, measure MC with a meter on delivery and reject over-limit lots, and protect seasoned timber from re-wetting until fixed. Timber installed at its zone equilibrium MC is stable for decades; timber installed wet moves no matter how good the species or the joinery.