damp gurus - do I need to tank or will it dry out on its own?

[Westcountrygemini]

The grout in our shower cubicle is cracked, this is causing leaks into the wall behind which backs onto a bedroom. We are shortly getting the bathroom completely done including tiling so this will sort the shower issue we can see. However, I suspect the shower itself may also be leaking into the cavity it sits in between the two walls (Victorian property, man made cavity) as I know the concrete floor in the bedroom behind is definitely damp and there is obvious damp on the wall and behind the skirting.

Anyway ... Once I've had the bathroom completely sorted out, do I need to tank the damp wall in the room behind or can I just let it dry out? What about the concrete floor, will that dry out underneath the carpet on its own or so I need to lift the carpet and let it air so to speak.

Am a real novice at all of this, would appreciate any advice so I don't end up spending money on tanking areas where it's not required.

[wowfudge]

You could tank the bathroom to stop water penetrating the wall and floor, but you wouldn't tank the wall and floor on the bedroom side. That needs to dry out and you may need some replastering and replacement of woodwork if it's damaged - the joists will need to be checked.

[Westcountrygemini]

wowfudge thanks, do you mean joists in the wall? Sorry if that's a real numpty question, I am a bit clueless about these things!

[PigletJohn]

What is the wall made of?

[wowfudge]

Joists are in the floor. When you say concrete floor in a bedroom, what floor of the property is this on? You'd usually only find concrete under a hearth, so close to or where there had been a fireplace.

[Westcountrygemini]

Ah, should have mentioned this earlier, sorry.

It's a early Victorian basement flat with concrete floors. The walls are made of brick, although, as the shower juts out from the wall, I think there's a false cavity its housed in so there are probably wooden joists there.

I know the floor in the bedroom behind the shower is damp because I had a carpet laid there last year and the guys told me that. As the floor in the bathroom is raised (there's a step as we enter, it's all bloody weird), I suspect that's damp underneath as well.

The bathroom was clearly bodged by the last owner and it's the last room we need to do a complete overhaul on - I wouldn't be surprised by any sort of oddness that's found!

[PigletJohn]

If it is a partition wall made with wooden studwork and a skin of plasterboard or L&P, rip the skin off the bathroom side and replace it with a cement-based tile backing board suck as hardiebacker, which is undamaged by damp. The tiler will (should) be familiar with the method.

Take the opportunity to replace any pipework concealed in the wall at the same time, and to let the timber dry out, and to replace any water-damaged timber.

[SharingMichelle]

I don't know but "damp gurus" is so good I'm considering making it my next username.

DampGuru.

[Westcountrygemini]

Thanks PJ and wow, that's really helpful advice.

[wowfudge]

If it's a basement flat then the whole flat should be tanked - the outside walls and the floors if the internal walls are stud walls. Is it definitely a problem with the bathroom or has the tanking failed somewhere?

[Westcountrygemini]

The outside is rendered, the walls are all brick. There is tanking in some areas of the flat internall, some done by the previous owner and some by us (well, not personally, by someone who knew what they were doing) last year before we moved in after we had a specialist damp survey.

The last room to be touched is the bathroom. It's definitely damp in there because the horrendous shower has the previously mentioned cracks in the grout plus I don't think the tray is sealed properly hence leaking into the suspended floor also.

Basically, am thinking we just need to rip out the bathroom in it's entirety, uncover all issues, get them sorted, make sure we instruct the tilers to use the backing board as suggested by PigletJohn. Deal with that, give it time to dry out in bedroom behind and, then, if we still have some signs of damp, further investigate the cause.

Does that sound sensible?

[wowfudge]

Yes - sounds sensible. Hire an industrial dehumidifier to dry everything out once you've got the bathroom ripped out.

[Westcountrygemini]

wowfudge again, thanks, will do!