Edward Thompson
Hi Danielle you would not expect it to affect the floor joists but it's possible mortar around the joists has been vibrated loose if the plaster was remove with an electric breaker, this may cause movement in the joists giving the bounce. Alternatively were the joists checked for rot when the damp course was installed? If not it maybe that they were rotting and the extra loading from all the loose plaster and persons removing it have finished them off! All speculation without taking a look but gives you possible causes. Ed
