Checks the horizontal displacement of solid-timber or glulam walls, frames and columns at the serviceability limit state: the combinations of SIA 260 from your elastic displacements, creep to SIA 265:2021, and the limits of SIA 260 annex A, table 4. Every step shows its formula and the clause it comes from.

What it checks

Creep coefficient φ from SIA 265 clause 3.2.2.2, table 5, for the service class and the moisture of the timber when installed.
Function, incorporated elements (SIA 260 annex A, table 4): for ductile elements, the frequent combination of the variable actions against h_storey / 200, instantaneous u_el = u_el,f and long term u = u_el,qp · (1 + φ) + u_el,f − u_el,qp. Brittle elements are checked under the rare combination against h/500.
Function, use and operation: the frequent combination against H / 300, u_el = u_el,f + u_el,G and u = u_el,G · (1 + φ) + u_el,qp · (1 + φ) + u_el,f − u_el,qp.
Appearance: the quasi-permanent combination of the variable actions against h_storey / 250, u_el = u_el,qp and u = u_el,qp · (1 + φ).
Governing row and its utilisation.

What you enter and what you get

You enter the member (wood type, strength class, service class), one direction or two, the storey height h_storey, the height of the building H, the moisture when installed, the incorporated elements, and which displacements to verify (instantaneous, long term or both). You then enter the elastic horizontal displacements from your own analysis, one per action: u_el,G, u_el,qp, u_el,f and u_el,r. The limits are pre-filled from SIA 260 annex A, table 4, and editable.

You get each limit and combination, the utilisation of each row with a pass or fail, and the governing row. With the Basic plan, it prints as an A4 calculation note.

Assumptions and limits

Footnote 1 of table 4 restricts every row but H/300 to the variable actions, so u_el,G is left out of those three combinations.
A storey carries either brittle or ductile incorporated elements, not both, so only the matching row of table 4 is verified.
In two directions, the limit is compared with the resultant √(u_y² + u_z²).
The differential displacement between two storeys is not verified; enter the storey drift as the displacement.
Buckling of the column is verified in its own module and the fire situation separately; the deflection of a beam follows table 3 in the beam deflection module.

Worked example

A glulam column GL24h in service class 1, installed conditioned, displacing in one direction, with a storey height of 3.00 m, a building height of 12.00 m, ductile incorporated elements, and elastic displacements of 1.2 mm (permanent), 2.0 mm (quasi-permanent), 6.4 mm (frequent) and 9.1 mm (rare). These are the module's own results for its worked example, computed when this page was built.

Inputs
Input	Value	Ref.
Wood type	Glulam
Strength class	GL24h
Service class η_w	1	§ 3.2.1.3 t.4
Displacement acts in	One direction
Storey height h_storey	3000 mm	SIA 260 §A t.4
Height of the building H	12000 mm	SIA 260 §A t.4
Moisture when installed φ	Conditioned	§ 3.2.2.2 t.5
Incorporated elements	Ductile elements incorporated	SIA 260 §A t.4
Displacements to verify	Instantaneous and long term
Permanent actions u_el,G	1.2 mm
Quasi-permanent variable u_el,qp	2.0 mm
Frequent variable u_el,f	6.4 mm
Rare variable u_el,r	9.1 mm
Function — ductile elements incorporated h_storey / n	200	SIA 260 §A t.4
Function, use and operation H / n	300	SIA 260 §A t.4
Appearance h_storey / n	250	SIA 260 §A t.4

Calculation: Common values
Step	Value	Ref.
Creep coefficientfrom table 5 for timber installed conditioned in service class 1	φ = 0.60	§ 3.2.2.2 t.5

Calculation: Check 1 — Function — ductile elements incorporated
Step	Value	Ref.
Function — ductile elements incorporated (frequent combination, variable actions) — limith_storey = 3,000 mm, the storey height, divided by 200	h_storey/200 = 15.00 mm	SIA 260 §A t.4
Function — ductile elements incorporated (frequent combination, variable actions) — instantaneousu_el,f. Elastic value, without creep.	u_el = 6.40 mm	SIA 260 §A t.4
Function — ductile elements incorporated (frequent combination, variable actions) — instantaneousu_el ≤ h_storey/200	η = 0.427 · Pass43 % of the capacity used	SIA 260 §A t.4
Function — ductile elements incorporated (frequent combination, variable actions) — long termu_el,qp·(1+φ) + u_el,f − u_el,qp. Creep added through φ.	u = 7.60 mm	SIA 260 §A t.4
Function — ductile elements incorporated (frequent combination, variable actions) — long termu ≤ h_storey/200	η = 0.507 · Pass51 % of the capacity used	SIA 260 §A t.4

Calculation: Check 2 — Function, use and operation
Step	Value	Ref.
Function, use and operation (frequent combination) — limitH = 12,000 mm, the height of the building, divided by 300	H/300 = 40.00 mm	SIA 260 §A t.4
Function, use and operation (frequent combination) — instantaneousu_el,f + u_el,G. Elastic value, without creep.	u_el = 7.60 mm	SIA 260 §A t.4
Function, use and operation (frequent combination) — instantaneousu_el ≤ H/300	η = 0.190 · Pass19 % of the capacity used	SIA 260 §A t.4
Function, use and operation (frequent combination) — long termu_el,G·(1+φ) + u_el,qp·(1+φ) + u_el,f − u_el,qp. Creep added through φ.	u = 9.52 mm	SIA 260 §A t.4
Function, use and operation (frequent combination) — long termu ≤ H/300	η = 0.238 · Pass24 % of the capacity used	SIA 260 §A t.4

Calculation: Check 3 — Appearance
Step	Value	Ref.
Appearance (quasi-permanent combination, variable actions) — limith_storey = 3,000 mm, the storey height, divided by 250	h_storey/250 = 12.00 mm	SIA 260 §A t.4
Appearance (quasi-permanent combination, variable actions) — instantaneousu_el,qp. Elastic value, without creep.	u_el = 2.00 mm	SIA 260 §A t.4
Appearance (quasi-permanent combination, variable actions) — instantaneousu_el ≤ h_storey/250	η = 0.167 · Pass17 % of the capacity used	SIA 260 §A t.4
Appearance (quasi-permanent combination, variable actions) — long termu_el,qp·(1+φ). Creep added through φ.	u = 3.20 mm	SIA 260 §A t.4
Appearance (quasi-permanent combination, variable actions) — long termu ≤ h_storey/250	η = 0.267 · Pass27 % of the capacity used	SIA 260 §A t.4

Calculation: Governing row
Step	Value	Ref.
Governing rowat 50.7% of its limit.	– = Function — ductile elements incorporated, long term

How this module is verified

Verified clause by clause against SIA 265:2021 and against independent calculations used on real projects, before release.

Questions

Why is it called h_storey and not h?

Table 4 writes the storey height as h. The module calls it h_storey so that it cannot be confused with the section depth.

Does sway under wind creep?

Sway under wind alone is instantaneous. Only the part of the action that stays for a long time creeps: u_el,qp carries φ in every long-term combination.

Can I print the calculation?

The full calculation is shown on screen, free and without an account. A print-ready A4 calculation note is part of the Basic plan.

Norm: SIA 265:2021 · Page updated: 21 October 2026

Horizontal displacement of timber columns and frames

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