Load-bearing timber structures — what geometry doesn't decide

As a carpenter you work out geometry every day: numbers of pieces, linear metres, material consumption, rafter lengths and stairs. It is pure maths on your own measurements, and Discebo's calculators can help with that. But there is a sharp line between that and the structural design of a load-bearing construction.

Geometry answers »how far« and »how many«. Sizing answers »how large a cross-section«, »what centre spacing« and »will it hold the load« — and that depends on loads, the material's strength class, span and deflection requirements.

• 01Geometry (your tool here): quantity, linear metres, area, volume, rafter length, the stair's step dimensions.
• 02Dimensioning (structural calculation): beam/rafter cross-section, permissible span, centre distance, brackets and anchoring.

Load-bearing timber structures in Denmark are designed to Eurocode 5 (DS/EN 1995) with national annexes, and serviceability requirements follow the building regulations (BR). Loads are determined to the Eurocode 1 series. It is the standards basis — not a rule of thumb — that decides whether a cross-section holds.

A drawing can show where beams and joists lie without showing what keeps the building stiff against horizontal forces (wind). The bracing is a separate system: wind braces and diagonal straps, shear wall and floor and roof panels, and continuous anchoring lines that lead forces down into the foundation. Removing a wind brace or bracing panel 'because it's in the way' can weaken the entire building even if each individual beam looks correct.