property renovation

My friend had her 1940s house renovated in the summer of 1999, would the builders who done the work have known if there was asbestos in the property before doing the work. This is something I’ve always wondered if builders are gutting an old house and asbestos is known to be in old wall plaster, flooring, boilers etc, how do the builders know if the old plaster etc that they are ripping out contain asbestos or not, or do they do tests first. I live in the Uk.

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