Damp bathroom floor

[ilikecobwebs]

This is a question asked considerably in advance of any work we have planned, but any thoughts will help.
At some point in the next couple of years, we plan to update our bathroom. Its on the ground floor, situated in what used to be the hallway of the cottage. The bathroom suite is 1970's green, the shower is nacked...but its the floor that is posing us a problem because every time it rains, the floor gets damp (stays dry otherwise....most of the time).
It has the remains of old quarry tiles on it and the previous owner painted a type of black sealer over them, which is now breaking down. It seems inevitable that we'll have to dig it up and membrane it, but we don't know what the current regulations are for this work.
We had all our ground floor rooms membraned in 1987, so its a long time ago now and memory has failed. We didnt do the bathroom at the time because we didnt have the money to fork out to replace the suite as well as having the floors done. The house is late Victorian, so nothing in the way of foundations bar good old soil and a scattering of rubble.

 

[Penners]

Quarry tiles in a bathroom are bound to suffer from considerable condensation, because they're cold in a steamy environment. Rainy weather may be exacerbating this by making the earth under them wet (which could make the tiles even colder).

The problem with introducing a damp-proof membrane into the floor is that you could simply force the sub-floor moisture to seek an alternative exit route up the walls. Unless, that is, the walls have a dpc - in which case you'll need to make absolutely sure that your membrane is continuous with the dpc.

If there's no dpc, I shouldn't be in any rush to put a membrane under the floor. Is the room well heated and ventilated? If not, then my first port of call would be a good extractor fan, and a heat source. The two combined could produce a significant improvement in the wetness of the floor.

 

[ilikecobwebs]

OK, thanks....understood that. The walls were damp-coursed in 1984 (lots of drill-holes everywhere). The heating is via a decent radiator, but admittedly the ventilation isnt very good; just a string-pull circular thing in one of the windows....ventilation is one of the issues we were going to have to address when we did the work. That'll give us something now to put our thoughts around.