Building the Conical Roof

 Time to put the roof on our 9 sided structural frame

New tarpaulin position

Originally the load bearing structure of the roof was to be 9 big beams running from the post and beam joints to the centre, where they would be supported on a triangle of centre posts. Our engineer worked out the loads on the roof and because of the long overhang the loads either side of the walls were equal, this made the centre posts unnecessary.
 I was not totally sure about how to build the roof now but thought we will figure it out when the time comes.
 The time eventually came and I was none the wiser, we had a visit from our builder friend Ossi who suggested doing without the 9 big roof beams and making 36 roof "elements", a sort of home made roof truss consisting of a double rafter joined with pieces of plywood. So the roof had a change of design which sorted out allot of technical questions.

Karel making the housing joint for one of the last few rafters

The rafter truss elements are made of a 4.2m sawn pine 5"x2", a 7.2m long 120mm min. diameter (at the wall loading point) roundwood spruce log and four 350mm wide 12mm salvaged plywood pieces fixed at 1.2m centers with 3"nails.
The roundwood elements we cut slots in or made flat surfaces with the chainsaw so the plywood could be fixed to them.

Roundwood rafter with slot and flattened surfaces

Rafter truss fixed in position

 At the centre of the house space needs to be left for the chimney so the rafters are fixed to a ring which we made by glueing and screwing 3 layers of 4"x2"s.

Centre ring

We wanted the roof to look round which means the rafters need to be in different positions on the supporting beam.

Rafter position at post and beam joint

Rafter position at halfway between posts

Checking intermediate rafler housing joint

 We fixed some temporary diagonal braces to stop the whole thing going into a downward spiral!

Lots of wood!

  Now we are working on the 3 dormer roof windows, after them the roof can be sealed up for the fast approaching winter.