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OBC DIVISION B · PART 9 · SECTION 9.38 — LOG CONSTRUCTION

How much settling allowance do log homes need above windows, doors and partitions in Ontario?

Log walls shrink and settle as logs dry, so the Code requires construction to accommodate that movement: slip joints and settling gaps above windows, doors, partitions and posts, and adjustable connections, so non-settling elements are not crushed or racked.

Code reference
Log construction must make provision for the vertical shrinkage and settlement inherent in stacked solid timber. Openings, interior partitions, columns, chimneys, stairs and plumbing runs that do not settle with the log work must be detailed with settling spaces, slip connections or adjustable hardware so differential movement over the drying period does not damage the building or bind windows and doors.
OBC Division B, Section 9.38.

Paraphrased for clarity — open this provision in the BUILDAiD Library for the exact wording.

What this means in practice

Green or partially seasoned log walls can lose several percent of their height, which on a full-storey wall means multiple centimetres of drop over the first years. Windows and doors sit in slotted bucks with a compressible gap above; frame partitions and posts get screw jacks or slip clips; plumbing stacks and chimneys need clearance sleeves. The classic failures are trimmed-tight drywall cracking along partition tops, doors that will not latch, and worst, a rigid stair or post that ends up carrying roof load. Plan re-adjustment visits into the first two heating seasons.

Plain language

Log walls slowly shrink in height as the wood dries, sometimes by several centimetres. Builders must leave hidden gaps above windows, doors and interior walls, with adjustable supports, so the house can settle without jamming or cracking anything.

Related questions

What are the code requirements for log walls in Ontario?

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This page is provided for general information. Building code requirements depend on your specific project, occupancy and municipality, and code editions change. Always verify requirements against the current Ontario Building Code and confirm with your local building department.