Hi fr2uk That is one hell of a 'notch', presumably 40mm waste pipes are going to be run in the 'notches'. Suggest you insist that the joists be reinforced by fitting supplementary joists under the existing ones, glued to them and bolted through old and new. One bolt should be fitted at the wall plate end and at least two bolts the other side of the 'notch'. Regards S
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