ROOFERS AT IT

The roofers started their work last week Thursday afternoon. As of this morning, they were about halfway, and are apparently under instruction from their boss to finish up today, whatever it takes. The roofers erect 76x50mm structural grade pine purlins over the rafters, with bracing where required by the engineer. They then attach Alububble insulation to the purlins with double sided tape. And the roof sheets are then screw fixed over this into the purlins.

The Alububble is a composite roll of bubble-wrap type white plastic insulating membrane with a foil lining on the upper side. This acts both as a water barrier in case of roof leakage, as well as an primary insulating membrane. We will supplement this insulation with further insulation above the ceiling boards.

The roof sheeting is formed from BlueScope Steel Colorbond Ultra steel in flat sheet roll form. It is then cut and pressed locally into IBR [inverted box rib] profile. The steel rolls come pre-coloured. We picked the White colour, for superior heat reflectivity. The steel is 0.53mm thick, and coated in a galvanising aluminium/zinc alloy with a coating mass of 200g/sq.m. The coloured paint is then bonded to the sheeting. The steel is imported in roll all the way from Australia, which is a pity. However, we were not prepared to purchase the locally produced Chromadek coloured galvanised steel sheeting produced by Mittal Steel, as it is widely held in the industry to be a vastly inferior product to the Colorbond. Environmentally, life cycle costs are just as important as initial build costs, so its a balancing act and a judgement call one has to make.

Roofing goes on while Table Mountain looks on

Interior view with Alububble underside visible