Dorma Window Construction

Today Dan and I continued on with our dorma window construction, which consisted of a 45 degree roof with an overall height of 2490 or 2455 not including the bottom plate. A 45 degree roof seemed rather simple in comparison to other pitches because the height always equals the half span of the roof. Because of this Dan and I thoroughly thought through each construction step and idea that came about so that we didn't overlook anything.

We constructed the main roof with the red roofing book as it was a fair bit easier to do so and building the dorma was the actual task, not the roof. One thing that both teams found annoying was that the edge cut for the rafters joining into the hips worked out to be 56 degrees but when we cut the rafters and tried to join them they were quite a significant amount out. So after some testing we just decided to simply go with a 45 degree edge cut, which fitted very nicely.

The diagram to the right shows the finished construction of the 45 degree roof that we had to work with. Notice that there is no jack rafter running up the middle to the crown end junction, this is so that the dorma window can be fitted easily. The two middle rafters are 900mm apart from one another, which was to be our dorma window opening. We used a 90mm birdsmouth cut, with the tail end totally removed. This provides a neat finish with no overhang.

Dan and I decided to put an opposing creeper to each side of the two middle creepers, so that they met up on the hip providing support to one another.

I enjoyed the construction of this 45 degree roof as i had always wondered what it would be like to make such a steeply pitched roof and i was wary of the ease at which things seemed to work. It was good to get even more practice at cutting rafters and hips without any supervision as i rarely cut them myself on the job site. Having two teams of 2 created a great rivalry between us and I enjoy the challenge of trying to build the roof faster than the other team.