A complete Danish reference work on carpentry and joinery — from measuring and centre spacings to rafters, stairs, floors and concrete. Read the articles. Use the calculators. Ask the assistant.
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Calculators
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Articles
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Questions
Symmetrical gable roof. Half the span (a) and the rise (b) are the legs; the rafter (c) is the hypotenuse. The angle α is the roof pitch — Pythagoras gives the length.
§ 01 — What you can do here
Five tools from look-up to installation — for apprentices, journeymen and consultants.
Measurement, centre spacing, Blondel stairs, rafter length and the boundary between geometry and structural calculation — the trade's knowledge gathered in one place.
Material usage, linear metres, number of rafters/battens, rafter length, stairs and concrete volume — pure geometry from your own measurements.
Checklists and process templates: joists, roof truss raising, partition walls, floor laying, concrete pouring and centre-to-centre setting out — ready for the site.
Structural timber, boards, cladding and flooring plus fastenings — with honest caveats about dimensions, strength class and load capacity.
A Claude-powered assistant focused on carpentry. Ask about measuring, geometry, material choice or work procedures — in Danish.
Your account, messages, forum and classes are shared across the other trades. Log in one place — use every sector.
§ 02 — Read now
Why 2·rise + going ≈ 61–63 cm
Count rafters, battens and posts correctly
Number of boards/sheets for an area
Concrete quantity using V = L · B · H
§ 03 — Tools
Enter the span, rise and overhang — and get the rafter length, the roof pitch and the diagonal overhang in seconds. The rafter is the hypotenuse of a right-angled triangle, so Pythagoras gives the answer.
Open calculators→Example · Rafter length & roof pitch
§ 04 — Next step
The AI assistant can calculate geometry, explain work procedures, compare materials and help with real-world cases from the site. Write to it as you would to a colleague.
Ask a questionTip: Rafter length & roof pitch — How long is the rafter, and what pitch does the roof get from the span and rise?
§ — Hvor kan du læse Carpenter?
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