Work it out.
Calculators tailored to the carpentry trade: measure the material consumption, divide the run into centre-to-centre spacing, find the rafter length, set out the staircase and work out the concrete. Enter your own values — the result updates live.
Directory
The guided workflow: answer house dimensions and chosen roofing material and get the complete roof specification brought together in one flow.
Measurement & material consumption
Start here: convert area into a number of boards/sheets and linear metres — with your own waste allowance.
Spacing & centre distance
Count rafters, battens and posts correctly over a span based on the centre spacing (cc).
Roof & rafters
Find the rafter length and roof pitch of a symmetrical gable roof using Pythagoras.
Stairs
Set the riser, going, and number of steps according to Blondel's stride formula.
Concrete & foundation
Calculate the concrete volume for a rectangular pour, so the concrete can be ordered in one go.
Building physics & material
Wood moisture and shrinkage, U-value against BR18, and how much cross-section burns away — the trade's physics check.
Shrinkage & moisture movement
Dimensional change with changing wood moisture
U-value — timber-frame wall/roof/floor
Heat loss through a flat construction
Fire charring & residual cross-section
How much wood burns away over time
Vapour barrier sits on the warm side of the insulation
Diffusion resistance for a layered vapor barrier