Shower removed - wet & rotton :(

[RJ]

lol! My shower project was going according to plan! Got all the facts I needed and about to go.

Removed some tiles today and the old shower tray - and to my surprise the whole lot is rotten!! See

for photos.

Massive rotton floorboards (chipboard), plasterboard etc.... If you look at the pre-photos I think it was due to the lip around the tray. This was a concrete step tiled over. Even though this appeared sealed, the grout and quality here was dire (hence the plan to redo the room).

We've pulled all the really knackered bits out and will take a better look over the next few days. Just happy to get air in there.....

So - now what!?!?!

Planning to remove all shower plasterboard from ground up to about

1.6m. Then put waterproof membrane behind, then use the "hardiboard" and seal, seal corners; then tile correctly with decent waterproof adhesive. I'm not too worried about this.....

I'll try and remove all the chipboard and replace. As you can see there are two joists in the center, and one either side just under the plasterboard wall. The last photo (with the pipe) shows how far the wet-patch goes. This pipe is c. 1m from the shower (e.g. if I put my arm in the hole and feel away from the shower I can only just touch the pipe if I *really* stretch.

There is no way I can remove all this board as it means ripping up floors in bedroom, landing and bathroom - the former two only just decorated. No sign of any issues in these rooms nor in the bathroom (bath panel removed and it looks bone dry(.

The joists look 99% okay - 2 of them are "flat" at the top, and 2 feel "u" shaped - possibly slight rot. Planning on just tidying these up only.

Plannig on removing as much of the rotten chipboard as I can reach, and then just ensuring everything drys out. (the pipes are central heating pipes which should help).

Then I was planning on laying a new chipboard floor - but I was going to ensure there was a 2+cm gap around all the edges where the current chipboard is damp. This floor will have a new shower tray (on stilts) installed (and decently fitted with tile upstands, chased into walls etc which will be the above board etc etc). As such - having 100% solid and joined floor is not needed. Hoping this gap *may* help with air circulation (under shower tray etc).

If any of the plasterboard frames are rotten (unlikely above 0.5m or

1m) I will remove the supports and put in new ones etc just to make it as strong as possible. The "base" wooden support (the one that touches the wooden floor) seems to be badly damaged and need replacing.

So - apart from venting my frustration - I'm seeking advice as to my above suggestions! Your advice generally is pretty good and it does help me a lot (novice DIYer who likes challenges. But not like this!)

Oh and FWIW - only planning on living here 5 more years.

THANKS ALL!

[bigcat]

) and seal, seal corners; then tile correctly with decent waterproof

this a framework wall? Or dry lined?

Better check its still sound in those other rooms, if it gives underfoot it needs replacing regardless of decor. Not difficult to make it all tidy again afterwards, very little damage is needed for that job.

are they ok or not? Theyre your most important bits after all.

I'd look at wbp ply for bathroom, chip dies the day it gets wet.

?

?

got ya. Sounds like overkill.

only necessary to cut out the rotten patches, not the whole length of any rotten woods.

this!)

Well, more work than planned, but nothing too puzzling there.

NT

[ryanjjones]

Nothing too puzzling "if" you've done this before! ;)

See > RJ wrote:

surprise

"hardiboard"

> ) and seal, seal corners; then tile correctly with decent waterproof

RJ> All internal walls, so framework.

RJ> Yes. airing cupboard/bathroom are behind RHS cublical wall. No carpet in AC and removed bath panel. NO SIGN of moisture. Landing do not believe so either but have not removed carpet. Bedroom - again do not know. No visible signs....

RJ> Will decide once I remove the chipboard. I'd say "yes" at the moment, but may need to treat them. One or two may have lost 1-2mm at the top (the bottom of the "u" bit) - but nothing major.

current

RJ> ;) - no extra work to leave circulation holes.

RJ> OK

RJ> Practice makes perfect.

RJ> If the chipboard floor in teh other rooms is dry on top and not showing signs of damage, I am planning just to dry everything out thoroughly and just leaving as is - and hope the chipboard survives albeit a little stained.

BUT - if I need to (bloody hope not) remove any other chipboard that goes across rooms - how is this done with walls above?!

And is there any rule of thumb that says "its okay to dry" vs "you must change". My current rule is "if I can break it with brute force its knackered - if I can't dry it and it'll be fine.". (Note - I made this rule up last night after a stint of bad language and beer)

[bigcat]

Treating them with chemicals achieves almost nothing.

yep, either it stands up and does the job or it doesnt.

NT

[Christian McArdle]

You mustn't use chipboard under a shower tray as you've found out. Use 18mm WBP ply which doesn't mind a soaking. Chipboard disintegrates at the slightest suggestion of water. Use a stone/resin tray bedded on mortar on top of the ply. Make sure it is correctly sealed.

Christian.

[ryanjjones]

Thanks Christian.

I'll hunt out some WBP ply (still don't know what WBP stands for!) ;) Consider chipboard idea forgotten.

I've already bought the shower tray - delivered tomorrow. Its a Mira one (c. =A3150) - so not a cheapie. Having it on "stilts" provided so I can keep panel access as needed (rest of floor will be tiled - so no way in). In addition to the provided stilts I was going to put a couple of timber cross members under the tray for additional support in case it ever decides to flex.

Christian McArdle wrote:

current

mortar on

[Christian McArdle]

It means Wash & Boil Proof. Basically means it doesn't mind getting wet (even with boiling water), as long as it isn't constantly submerged.

Christian.

[ryanjjones]

Cool! WTF didn't the builders use that in the first place :( Or at least give facilities to see what is going on underneath. ho hum

Cheers.

[Christian McArdle]

CHIPBOARD STANDARD 18X2440X1220MM (601001) £12.07 - SH PLYWOOD HARDWOOD WBP 18MMX2440X1220 (840803) £30.47 - SH

Christian.

[ryanjjones]

structural integrity of a whetabix the moment it does!

/far too familar a memory!

[John Rumm]

Water and Boil Proof - i.e. waterproof ply that does not delaminate when it gets wet, or "bubble" - but not as expensive a "marine" ply which is the same sort of idea but also guarenteed to not have any voids in it.

There is no absolute need for a floor at all under the tray - cross members straight onto the joists would do it.

If you must use chip on a floor then get the green tinted (i.e. waterproof) flooring grade chip made with a waterproof resin. It still looks a mess when it gets wet, but at least it does not take on the structural integrity of a whetabix the moment it does!

[Pete C]

Hi,

If you seal some flooring grade 'green' chipboard with paint, varnish PVA or better still resin, it should do very nicely.

People often forget that WBP and even marine ply is not rot proof, a classic case of thinking more £££ is better, plus a waste of hardwood too.

A layer of hardiboard over the floor would be another way, also if the flooring is well sealed to the walls so any leaks escape visibly instead of going down below that would be good.

cheers, Pete.

[Kenny of the Fells]

Actually, after recent attempts to clean up after my one year old has had breakfast, I'm wondering why they don't use a milk/weetabix mix for building. Sets harder than any cement...

KotF

[Nick Atty]

And, to merge threads, it's dishwasher proof if you let it set hard as well.

[bigcat]

You can use it as filler, and it sets hard. Its 2 issues are:

- it swells and disintegrates when wet

- rats and insects can eat it if they get to it

- and will go mouldy if it stays wet, so not for bathroom use.

NT