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Yanko Ivanov
  • Curated

Pergola Calculator

How many posts, beams and rafters a timber pergola needs, in what size, with a cut list, a price and a 3D model you can turn.

Rules of thumb for planning a shopping list, not a structural engineer's sign-off. Have someone qualified look at the plan before you cut anything.

3D model

Drag to turn it. Ctrl and scroll, or a pinch, to zoom. Arrow keys work too.

Shape

Build

m
m
m
m
Roof

Roof

mm
mm
mm
Timber and snow

Strength class

C24 is the usual one for sawn spruce and pine from a yard. Ask what yours is graded as.

kN/m²

Ground snow load at your site. 0.5 is light, 1.0 typical and 1.5 heavy, but those are placeholders: look up your municipality's value in the Eurocode national annex.

The timber

The lightest section in the list that passes. "Used" is how much of its strength the worst check takes: 100% is the limit.

Members of the pergola, with the section chosen for each and how hard it is working
Member Qty Section Used Result

Cut list

Cut

Every piece to cut
Qty Member Section Length

Buy

Boards to buy so that the cuts fit
Qty Section Board length

Cost

Ballpark placeholders, in euro. Type your yard's prices over them. They stay in this browser and go nowhere.

€/m³
€/m²
% of timber
€/post
€/post
€ each
Cost, line by line
Item What Amount
Total

What this assumes

  • Metric sizes and EN 338 strength classes for sawn timber, outdoors and exposed to the weather. Flat roof.
  • Rafters, beams and the wall ledger are treated as simply supported and checked for bending, shear and deflection (L/200, creep included). Posts are checked for compression and buckling, pinned at both ends. Eurocode 5 supplies the shape of the maths and the safety factors; this is not a Eurocode design.
  • Loads are the weight of every member, the covering (slats, or 0.15 kN/m² of sheet) and the snow you enter, applied straight to the roof. No wind, no people on the roof, no hanging planters.
  • Not checked at all: joints and fixings, footings and the ground under them, sideways loads and bracing, and the wall an attached pergola leans on.
  • Prices are placeholders. Type your own over them; they stay in this browser.