Mid-Winter 2011 we were asked to inspect this old Butynol roof on a block of 4 single story residential units which was leaking.
Over the last few years a variety of other roofing contractors had undertaken repairs to some sections of the roof, but the bottom line is that at 30 years old the roof has reached the end of its serviceable life.
At some point contractors had stripped in a cover/ detail tape over the original joints in the Butynol, and coated the black 1mm rubber with Aluminium Paint, which probably added another 10 years life to the roof.
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We gave the owner several options for re roofing the area, new 15mm plywood and 1mm or 1.5mm Butynol, or re use the existing substrate and 1.5mm Butynol, Grey or Black. The old substrate was quite springy so we were not happy with just 1mm membrane in that situation. To re-use the existing substrate it would have to be rescrewed and the existing nails punched down and then sanded off all over.
In the end he chose the cheaper re-use existing substrate option, but with the 1.5mm Grey Butynol, which would help reduce the heat soak and keep the inside cooler in the Summer.
The first task on taking possession of the job site was to temporarily remove the bottom row of concrete tiles so that the new membrane could be dressed up underneath.
Also at the two walls the bottom weatherboard was removed, for the same reason.
2 layers of building paper was put in where the tiles and weatherboards came out, just in case of a shower of rain that night. It did, and then winds of 90kmph over the weekend and then the coldest day in 16 years. No water passed into the house below during the storm.
After that storm passed through the next step was to repair spongey areas with new plywood. The 1/2″ chipboard had survived remarkably well over the 30 years and the recent leaks only resulted in some minor sagging and damp patches in the wood. These areas had to be cut out and repaired and it was better to do this as a seperate task rather than have to do it when each section of roof was torn off
New Rubber Membrane
Two months later the owner of the adjoining unit asked us to re roof their roof.
This section had only leaked around one of the the outlets, and the substrate generally appeared in reasonable condition with just some sheets that had sprung up due to nail head rusting, causing ponding water.
Same specification as the earlier roof, re-screw, punch old nails down, sand, silicone taped joints and 1.5mm Dove Grey Butynol.
As it happened the weather in September was worse than in the Winter, with drizzly and showery conditions every second day. The first strip torn up was quite small because of the risk of rain.
I had two different helpers on this job, as it did drag out (because of the bad weather), Slavko from Slovenia and Tamba from Sierra Leone.
After a week of rain and wind, a restart on the last central section. No leaks during the storm, thanks to seam taping the temporary overlaps onto the old rubber.
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