Roofed
March 29th, 2008 - Posted in eco-building - by Brendhan|
We have finally roofed our workshop! Given the fact that it is nestled in a patch of native bush we selected Karaka green for the colour of our corrugated roofing steel. The steel is screwed onto the (mostly) untreated lawsons cypress building frame using colour matched roofing screws.
Untreated lawsons cypress workshop frame with chemically treated pine trusses.
We intend to use this workshop year-round and do not want it to get either too hot in the sun or cold in the winter so we have elected to insulate it. To allow this we have a layer of ‘whitecap’ under the purlins supported by wire netting. The whitecap is white on the underside to improve the general lighting inside and silver on the top to assist the insulation. The insulation is then placed on top of this between the purlins, roofing paper is placed over the purlins to control condensation on the underside of the steel roofing and then finally the roofing is screwed to the purlins.
The various layers; whitecap (shiny stuff just visible in front of the insulation), R1.8 Terra Lana wool/polyester insulation, roofing paper and steel roofing.
The obvious problem here is what happens if it rains before we cover up the insulation? Thankfully due to good planning and a huge tarp (OK mostly the huge tarp!) we didn’t have that problem. Mainly the problems revolved around the two sections of roof that were clear corrugated polycarbonate (clear-light) and getting them into the correct position. These had to be located between the trusses so the insulation can be blocked in later on top of the trusses and because we don’t want a bloody great truss in the middle of the clear-light. In the end this meant cutting two pieces of the roofing steel in half and putting half between the clear-lights and half in front. Cutting the two bits of roofing took about four hours of scouring with a sharp implement and then bending along the line. However we have ended up with the clear-lights in the right place.
First clear-light in place! -Note the tarp on the left.
After the clear-lights were sorted (and a quick break to pick up Sarah’s parents from Wellington) it was fairly plain sailing to the front of the roof. The reason we worked from the back of the roof forward is so that the overlap faces away from the prevailing wind and therefore water will not get driven between the sheets. Peter and Kathleen seemed happy to spend a couple of days sitting in our recently acquired deck chairs (thanks guys!) watching us put up the remaining sheets.
Roof finished and hat in the air!
