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
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
Measure, calculate, build — or ask.
Eight tools from booking to installation — for apprentices, journeymen and advisers.
Tools in the trade
§ 02 — About the trade
Carpentry
Carpentry is the timber trade that raises a building and closes it against wind and weather — rafters, floor joists, non-load-bearing partitions, façades, windows and doors. The trade works on site from drawings and structural calculations, and it rests as much on geometry and measuring as on craftsmanship: centre distances, rafter lengths, material consumption and stairs are calculated before anything is cut.
Questions about the trade
What does a carpenter do?
A carpenter builds the timber structure of the house and closes it against the weather. The work runs from setting out and foundation through raising rafters and laying floor joists to sub-roof, battening, façade cladding, non-load-bearing partitions, subfloor and fitting windows and doors. A large part of the day is measuring: the reference line is snapped, the right angle is set with the 3-4-5 method and checked on the diagonals, and the centre distance is set out cumulatively from one fixed zero point so the last bay fits. The carpenter builds to approved drawings — dimensions and spans come from the structural calculation.
What is the difference between a carpenter and a joiner?
Carpenter and joiner are two branches of the same timber craft. The carpenter handles the load-bearing work and everything built on site: beams, rafters, roof structures, wall frames, floors and cladding. The joiner handles the finer work that demands tight joints, smooth surfaces and precise fitting — windows, doors, stairs, mouldings, panelling and fixed fittings, often made in a workshop. The division is old, but it lives on in the education system, where carpenter and building joiner are related yet separate vocational programmes.
How do you calculate a staircase using Blondel's rule?
Blondel's pace rule states that 2 · riser + going must fall between 61 and 63 cm. The riser is the vertical height per step, the going the horizontal depth, and the interval corresponds to an average pace. The calculation always starts from the storey height — the vertical distance between two finished floors — which is divided by the desired riser and rounded up, so no step ends up higher than intended. A storey height of 280 cm with a desired riser of 17.5 cm gives 16 risers of 17.5 cm and a going of 63 − 2 · 17.5 = 28 cm.
Which standards apply to load-bearing timber structures?
Eurocode 5 — DS/EN 1995-1-1 with the Danish national annex DK NA:2024 — is the standard load-bearing timber structures are designed to in Denmark. It distinguishes between the ultimate limit state (ULS), where the structure must carry the load, and the serviceability limit state (SLS), where deflection must be acceptable in use. Loads come from the DS/EN 1991 series, snow and wind from DS/EN 1991-1-3 and DS/EN 1991-1-4 DK NA:2024. The strength class of structural timber follows DS/EN 338, and load-bearing timber must be strength-graded and CE-marked to DS/EN 14081-1. On top of that, the Danish building regulations BR18 add the structural classes KK1–KK4, where a certified structural engineer is required from KK2.
How do you become a carpenter?
Carpenter is a vocational education that begins with a basic programme at a vocational college and continues in an apprenticeship with a master carpenter, where the student alternates between school periods and work and is paid along the way. The programme takes up to 5 years and ends with a journeyman's certificate; along the way you can specialise as a floor layer or a thatcher. The content is equal parts craft and calculation: drawing interpretation, measuring and setting out, centre spacing, rafter length with Pythagoras, material consumption and stairs — plus material knowledge, joints and fittings, fire and moisture.
Based on: DS/EN 1995-1-1 DK NA:2024 · DS/EN 1991-1-3 DK NA:2024 · DS/EN 1991-1-4 DK NA:2024 · DS/EN 338 · DS/EN 14081-1 · BR18 · Blondels regel
§ 03 — Read now
Featured articles
Featured articles
All articles →§ 04 — Tools
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
§ 05 — Trade in Action
How it looks craftsmanship.
Three classic working methods from the trade — drawn as blueprint: rafter raising, board laying and vapour barrier in roof construction.
Work processes
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.
Roof laying on rafters
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 placement in roof construction
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.
§ 06 — Next step
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.
Ask a questionTip: Rafter length & roof pitch — How long is the rafter, and what pitch does the roof get from the span and rise?
Safety
Come home in the same state
Tømreren bygger det andre går på. Du står på spær, lægter og stilladsdæk, mens huset endnu ikke har hverken gulv eller rækværk — og du bruger dagen igennem maskiner der skærer, skyder og støver. Faldet fra taget er det der slår tømrere ihjel, og træstøvet er det der langsomt tager lungerne. Begge dele afgøres af det du sætter op, før du går op.
Safety course
42 modules · 385 min · 5 farer der kan dræbe
§ — Where can you read about Carpenter?
Find a school nær dig.
Tømrer (træfagenes byggeuddannelse) is offered at 30 places in the country. The list is informational — always check the latest and complete offering on the Education Guide's vocational education map.
Schools offering the programme
Hovedstaden
04- NEXT Uddannelse København — København
- U/NORD — Hillerød
- NEXT Uddannelse København — København / Glostrup
- Campus Bornholm — Rønne
Sjælland
07- CELF — Nykøbing Falster
- EUC Sjælland — Køge
- Roskilde Tekniske Skole — Roskilde
- ZBC (Zealand Business College) — Næstved
- ZBC — Slagelse
- EUC Sjælland — Næstved
- EUC Nordvestsjælland (NEG) — Holbæk
Syddanmark
05- HANSENBERG — Kolding
- EUC Lillebælt — Fredericia
- EUC Syd — Sønderborg
- Rybners — Esbjerg
- Syddansk Erhvervsskole (SDE) — Odense
Midtjylland
10- AARHUS TECH — Aarhus
- College360 — Silkeborg
- Den Jyske Håndværkerskole — Hadsten
- Learnmark Horsens — Horsens
- Skive College — Skive
- Tradium — Randers
- Uddannelsescenter Holstebro (UCH) — Holstebro
- VID Erhvervsuddannelser (Viden Djurs) — Grenaa
- Mercantec — Viborg
- Herningsholm Erhvervsskole — Herning
Nordjylland
04- EUC Nord — Hjørring
- EUC Nordvest — Thisted
- TECHCOLLEGE — Aalborg
- HEG — Aars