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2 · riser + going ≈ 61–63 cm·c² = a² + b²·spacing · rafters · battens · joists·Eurocode 5 · DS/EN 1995·V = L · W · H·A reference work in Danish·
2 · riser + going ≈ 61–63 cm·c² = a² + b²·spacing · rafters · battens · joists·Eurocode 5 · DS/EN 1995·V = L · W · H·A reference work in Danish·

Carpentry
the trade,
explained.

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.

12

Calculators

28

Articles

Questions

Fig. 01

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.

Measure, calculate, build — or ask.

Otte værktøjer fra opslag til montage — for lærlinge, svende og rådgivere.

Work it out.

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

Gable roof · span 8.0 m

Pythagoras
Span8,0 m
Half span (a)4,0 m
Rise (b)2,0 m
Roof pitch26,6°
Rafter length (c)4,47 m

How it looks craftsmanship.

Tre klassiske arbejdsgange fra faget — tegnet som blueprint: spær-rejsning, lægtelægning og dampspærre i tagkonstruktionen.

Rafter raising with support

The carpenter raises the rafter frame and attaches it to the ridge with angle brackets and nails. A perforated band anchors against wind load, the rafter projects over the masonry edge as an overhang and a plumb line ensures the rafter stands upright against the roof plane.

PLACEHOLDER_102

The carpenter lays the battens perpendicular over the rafters with equal center-to-center spacing, nails them at each intersection and measures along the rafter with a tape — the top batten is checked with a level.

Vapour barrier/substrate closed and tight at end of day (construction moisture)

The carpenter unfolds the vapor barrier film behind the insulation and seals the joint: the strips overlap and the overlap is taped so the interior lining closes the structure air-tight. The overlap dimension is indicative — always follow the manufacturer's instructions.

One question
in Danish.

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.

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Tip: Rafter length & roof pitchHow long is the rafter, and what pitch does the roof get from the span and rise?

Find a school nær dig.

Tømrer (træfagenes byggeuddannelse) is offered at 25 Places that are particularly assessed: edges, corners, joints, seams, and under furniture in the country. The list is informational — always check the latest and complete offering on the Education Guide's vocational education map.