Measures · Timber beam
Timber beam pre-sizing FREE
Work out the depth and width of a timber beam from its span and spacing. Below the result you find the formula and the standard.
Indicative pre-sizing. It does not replace a structural calculation signed by a licensed engineer. For seismic zones with agS (design ground acceleration) > 0.15g, long spans or use classes III/IV → talk to a structural engineer.
Pick a calculation from the list to start.
Formula, example and standard
h ≈ L/15 ÷ L/20 · b ≈ 0.5 ÷ 0.7 · h
Example with the starting values (Span L: 5 m; Spacing: 0.6 m): Depth h ≈ 25–33 cm. Width b ≈ 13–23 cm.
- Valid for L < 6-7 m with standard residential loads.
- Glulam over longer spans needs a dedicated calculation (EC5 criteria).
- Always check deflection as well as strength.
Source: NTC 2018 ch. 4.4 · Promo Legno · biblus.acca.it
Indicative pre-sizing: it does not replace a calculation signed by a licensed engineer.
The other calculations
Steel IPE beamReinforced concrete beamReinforced concrete columnSteel columnTimber columnRC cantilever / balconyLintelClay block and concrete slabTimber floorPredalles slabLoad-bearing brick wallPartition wallStaircaseMinimum room heightWindow-to-floor ratioEscape route widthNumber of toiletsNTC imposed loadsExternal insulationVentilated crawl spaceRoof pitch