I have come across a bay window of a customer, who has sash windows with no stone sub sill (see link below) instead they have a wood sill, which has rotted and been covered over with plywood. I dont know if there was a sub sill originally. My prefered method to repair would be to cast a new sill all round in concrete, but my concerns are if I use a DPM between existing wall, sash frame and new sill. It might not hold in place with the weight of the concrete (as their might be no grip). If I dont have a DPM between sash and sill water might soak into the frame and cause further rot / leaks. Any suggestions would be appreciated from persons who know what they are talking about and stick to the point. Thanks Martin [IMG]
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