Carpentry (Zimmerer)
A roof truss is built twice: once in the workshop and once on the roof. In the quote it usually stands as a single item — and then half the work is invisible.
How it is billed
Roof trusses go by the cubic metre of timber or the square metre of roof area, rafters and purlins by the running metre, battens and counter-battens likewise, boarding by the square metre. Carports, canopies and garden buildings usually as a lump sum, assembly and rework by the hour. Glulam has its own price per cubic metre and its own lead time, so it does not belong inside the item „roof truss". Areas and volumes are worked out in the program itself: you enter the dimensions roof area by roof area and member by member, name every measurement your own way, and the total goes into the quote as a finished item with the breakdown — you can see where the figure came from.
What disappears on paper
What disappears is the workshop. Cutting, drilling, carpentry joints, timber treatment — hours nobody sees, because they happen before anyone drives to site. If the quote holds a single item „roof truss", those hours have nowhere to sit. The crane day disappears too: you book it for a date, and if the crew before you has not finished the floor slab, the crane stands and the waiting time is on your bill. Add changed sections after the structural check, transport of the elements, and cutting on site that was never planned.
Work it out yourself
Take the last roof truss. Count the hours your people spent in the workshop before anything went to site — then check how many of them appear in the quote. Add the crane day if it waited. Multiply by your hourly rate and by the number of trusses in a year. That is not a loss on material but on time nobody counted.
Five minutes a day
A photo of the structure before the boarding and before the covering. It shows sections, spacings, joints and timber treatment — after that everything vanishes under board and tile. In the evening: workshop hours separately from hours on site, timber deliveries, fittings used. When the question about load capacity or timber protection comes in three years, the dated photo answers for you.
What the program watches for you
When you work for a construction company, the program sets the reverse charge under §13b and watches the §48b certificate — without it your client must withhold fifteen per cent. It watches the instalment invoices, because you buy the timber before assembly, so the money leaves before it arrives. It watches the warranty periods: under a VOB/B contract it will not accept less than four years, under a works contract governed by the German civil code less than five. Additional work is kept as a variation with the date it was announced.
At the end of the year
Timber is the biggest material item of the year and workshop hours the second biggest. Both are recorded against the jobs — together with fittings, preservative and kilometres between workshop and sites. The annual accounts read finished figures.
What matters is entering things regularly — workshop hours kept apart from hours on the roof show what a roof truss really costs.
