Leaking shower into floor joist

melodymaker67 · 10 Dec 2015

Ok, this is a messy job as we inherited it from the previous owners (he thought himself a top DIY/Builder) Had a new shower installed a few weeks ago but by chance I was looking under the bath to see how I could patch up the flooring (the bathroom gets very draughty) and I can see part of the floor joist is wet. In fact some of it is dry and comes off when I stick my fingers into it. It only seems to have started on the top of it but on further inspection the leaking is coming from old sealant letting in water when showering. I think I have caught it in time before the whole joist was ruined. I am afraid the yellow mess was my attempt a few years ago to fill the gaps with expanding foam (never again)

1) What type of sealant should I get that won't shrink/mould and last years or can I go over it with tile grout ?

2) Not strictly a plumbing question but how would you patch this area under the bath ? I plan to keep the bath but replace taps and plug.

polesapart · 10 Dec 2015

Silicone.

Meticulous removal of old and prep requiered..

Aquaheat · 10 Dec 2015

If you want to patch the floor up properly take this as an opportunity to do the job properly.

Remove the seal from around the bath, Isolate DHW and CW to the taps and disconnect the taps then disconnect the waste pipework.

Remove the bath and patch up the floor now that you have easy access. While the bath is out it is also easier to remove the old taps and waste and fit new. (trust me it will save you hours of swearing and grazed knuckles if the bath is out and you'll thank me later)

Clean up all the areas where silicone used to be and refit in reverse order. Turn back on your water feeds to check for leaks.

Fill bath to just below overflow level and remake the silicone seal around the bath. Allow 24hrs for full curing of the silicone then drain bath and check for any leaks on your silicone seal.

Best silicone to use for longevity and mould resistance is Dow Corning 785.

Jon

melodymaker67 · 10 Dec 2015

Thanks Jon. It's something I need to do but after Christmas I think. The whole bathroom tiles need to come off too but one step at a time. Will keep the bath but new taps will make it look good again. Some of those pipes under the bath cannot be removed as they are central heating. Also, would you fit flexible hose instead of click together plastic ?

Aquaheat · 10 Dec 2015

If you can hold off for a while then you would be best off doing all in one go as you will ruin the seal again when you do the tiles. Its easier and less upheaval to do it all together.

Pipes don't need to be moved as you can board over the heating ones in the floor and around those that pop up for the feeds to the taps.

With regards to the pipework i would do it in rigid myself but for ease of DIY then WRAS approved flexis would be fine.

One thing I would note however is that it appears to be 15mm pipework to you're taps which will more than likly be 3/4" so will have a reducer off the tap. I would fit 3/4" x 22mm flexible tap connectors and reduce down to 15mm when joining back to the existing copper. The reason being that flexible tap connectors have a very narrow bore. If you use 15mm flexis off 15mm pipework you will have a significant reduction in flow. 22mm flexis will prevent this happening as the bore will be similar to 15mm.

Or you could re pipe back to where it changes to 15mm when the bath is out. This would be my preferred option and what I'd want to do in my customers houses but it depends on how far you want to go. The above will still see you through.

Jon

melodymaker67 · 11 Dec 2015

In the meantime what would you suggest I do to stop water running down before I set to after Christmas as we need to use the shower?

Burnerman · 11 Dec 2015

In the meantime, get rid of that old silicone.....stanley knife, chisel or whatever (it looks like some of it will peel anyway) then dry everything as well as you can and apply new silicone. You'll need a heavy bead, and smooth it down with a finger.
Keep the bath panel off if you can to help drying, and you can inspect to see if your fix works.
John

ree · 11 Dec 2015

As above will work.

But you never grout over silicone- it wont hold.
If you remove the bath tub you might find that the bottom course of tile is loose but removing the tub would make patching the floor easier.
Surprised that you dont have water hammer - no pipe clips can be seen?

Assuming that this bathroom is on the ground floor:
Is there adequate ventilation below the joists?
Are the joist tails that sit in wall pockets sound - probe with a screwdriver after lifting the newish floorboard close to the skirting.
Do you mean that you can "stick your finger into" the rotting joist - or into something else?

melodymaker67 · 11 Dec 2015

It's a bit soft and spongy the very top layer but further back seems ok. I will have to get the bath out for further inspection. It's happened in the last few weeks as we have been without a shower for a long time until we had a new one installed.

Not sure what you mean by "water hammer". There seems to be a draught under the floorboards as it's an outside wall (I have had tried to plug the gaps with newspaper/old clothes) which got soaked from the water and sat on top of the joist. Taken all that out and just filled around the outflow bath pipe with bubblewrap to stop draught. Not ideal but it gets so cold in winter, even with a heated towel radiator. I need to lay a laminate floor so hopefully the draught will be stopped as it's bare floorboards at the moment. It's just a big job that all needs to be done but not before Christmas. The previous owners have left it a right pig's ear and as I am learning as I go along (with much appreciated help here) I don't want to rush it.

ree · 11 Dec 2015

If you pull the bath tub then give serious consideration to a bathroom re-fit.

The soggy joist sounds like extreme wet rot - this can often be cut out leaving a treatable, and if hefty enough, joist in place.

The new board by the left hand skirting doesn't go under the skirting - hence, another source for a draft.

melodymaker67 · 14 Dec 2015

Can I go over the top of the sealant there with Dow Corning 785 for a temp quick fix before I rip it all out in the next few weeks ? This is so we can still use the shower,

dazza87 · 14 Dec 2015

Depending how the baths been fitted you may be better refitting it when tiling etc.
I normally fit batterns around for bath lip to sit on prevents too much movement.
If baths moving slightly you will never stop it leaking.
check the flexi over flow hose aint leaking they can be swines

melodymaker67 · 14 Dec 2015

The old shower hose leaked all the time but this is a new one.

dazza87 · 14 Dec 2015

not shower hose,the black overflow in pic that goes into waste.

ree · 14 Dec 2015

As advised above - you should really clean out the old silicone and dry off - however, you could dry off the in-place silicone and go over it. It wont hold for long but ...

When you are ready to refurbish the bathroom then come back here.

diynot

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local

Leaking shower into floor joist

Similar threads