Start with four timbers, e.g. two of 4m and two of 5m of 20cm diameter
Make lap joints at each end by cutting half of the timber away over 10cm
Floor plate awaiting lap joints
Making a lap joint takes time and patience to get a good fit
Assemble the floor plate
Assemble four large uprights and two or more smaller ones, the height of the ceiling plus
Cut tenons on both ends of structure posts
Chisel mortices over the lap joints
Put structure posts in the floor plate
Select wall plates, e.g. 4m x 5m. Make lap joints
Fix wall plate on support posts
Work out length of rafters using geometry
Cut half the timber away on one end of rafters over at least 10cm for lap joint
Create lap joint fix with pegs
Fix roof to wall plate with mortice and tenon (Method 1)
Fix roof to wall plate using cut away wedge joints pegged (Method 2)