Post
by bedede »
Fri Jan 24, 2020 5:13 pm
Hello, I have built a summer house, timber framed, with a breather membrane. On top of the breather are roofing battens running the length of the structure, at 90' to the rafters. The curved corrugated roof is attached to the battens. The structure is currently uninsulated and not heated, well ventilated. So there is no created moisture rising from the structure through the breather to condense. This is more what I would describe as ambient condensation in the way that any metal surface (car, lampost, railing etc) will create condensation given the right conditions. It is producing droplets of water which are dripping onto the breather and producing damp spots. The breather is facing the correct way. Any ideas on how to address this. Perhaps the breather membrane is not of sufficient quality to resist standing water. Would placing insulation on top of the breather between the roofing batten gaps help or just remove the air flow making it worse. Or laying a secondary breather membrane over the battens then place sheeting on top, I think this could work and easy to do. I have only just noticed this, and if it only happens on our wettest days, and then dries out as it is very well ventilated, maybe not a problem. It is possibly something I can leave and monitor, and address in the coming months. I did recall some sheeting comes with a material bonded to the back to prevent condensation. None of construction diagrams I have seen for a cureved metal roof on a timber frame differ greatly from what I have done, all sit above the breather, and if the structure is well insulated will be cold and create condensation, is this a known trait of this type of roof. If you see the diagram, the structure would be the same, with addition of the roofing battens between the membrane and the sheeting. Anyone experience similar, thanks in advance
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