A bathroom is a question of where the water can go, and in Wellingborough there is a second question underneath it: how well the building sheds the moisture it already has.
In a valley town, where older buildings sit on ground that holds water, adding the wettest room in the house needs a bit more thought than elsewhere. Ventilation carries more weight, because the fabric has less spare capacity to dry out, and an extractor that discharges into a roof void rather than outside will find the timber considerably faster here than on a dry site.
Ground floor wet rooms deserve particular care for the same reason. There is no forgiving void beneath, the falls are tighter, and the tanking has to be right first time. They are good jobs when they are done properly and a persistent problem when they are not.
Floors upstairs bring the usual considerations. Joists were sized for a bedroom, not for a filled bath on a tiled floor, and where a waste run means notching or drilling them there are permitted zones we work to. We will move a fitting a foot rather than cut a joist where it must not be cut.
Tanking is not optional on a walk in shower, because tiles and grout are not a waterproof layer and never were. Our bathroom installations page sets out what a full refit involves.