Builders seem to have a jaundiced view of installing cavity closers. Possibly because it impacts on their profit margin and comes towards the end of the job.
Building regs. are clear enough so is this just something building control don't check or...?
Insulated plastic closers as you suggest. Builder arranged for window installers last week. When I went to check the job I found they had put in windows over open cavities.
Clearly the window installers didn't think it was their job either. I am still kicking myself for not going on site earlier.
I suppose the front edge can be trimmed off to allow a bodge fitting but it is not going to give much support for the window board.
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