Repairing a water damaged floor

[Giesse]

I am doing some renovating on my house. One of the first jobs to tackle will be the floor in the ensuite. It's chipboard flooring sheets with vinyl straight over the top. We've pulled the vinyl up and the chipboard underneath is pretty ordinary. There is (well, was...) a bath in the room and there have been plenty of overflows, I think, as the floor is badly stained, smells ATROCIOUS, and the chipboard has swollen about 5mm at the edges of the boards, leaving the floor rather warped. I'd ideally like to just replace it all, however the walls are all sitting on top of the floor, so replacing it may be kind of difficult without dismantling half of the house. I was thinking of:
1 - Cutting the flooring at the joists nearest to the walls and just replacing the main part in the centre (the edges aren't too bad).
or
2 - Using a belt sander to sand down the edges of the boards to roughly level the floor, give the whole thing a good sand-over, and then cover it all with masonite and leave it at that. The trouble is, I'm likely to die from the mouldy dust! I finished up wheezing and choking last time when we simply lifted the vinyl and swept the floor, let alone SANDING it! Still, there's always gas masks...

Does anyone have any suggestions as to the best way to go. I'm trying to do this as economically as possible.

[q9]

I'd suggest cutting as much of that chipboard aways as possible and replacing with a proper wet area flooring.

Is there a shower in there now replacing the bath? Is there a drain in there?

You may want to consider containing draining from spills somehow.

[zymurgy]

When I redid my bathroom, I replaced the floorboards with James Hardie (JH) compressed sheeting (18mm). It's like having a concrete floor!

In my case I went back to the studs when I did the bathroom, relined with JH villaboard and tiles on top.

Major job, major costs including replacing window with glass bricks. But worth every penny.

I think if you cut corners, especially in wet areas (and that's what your builder did), it'll only come back and bite you.

Gordon.

[Giesse]

At the moment, the only thing left on the floor is a toilet, but that will go shortly. I will be installing a shower where the bath was (won't THAT be a fun job...) so hopefully there won't be too much more trouble with water spillage.

Gordon, sounds like more than I'd be looking to spend. This house really doesn't warrant it (unfortunately), so I just have to do the best job I can afford. Taking the flooring back to the studs might be difficult since there would be no joists at the walls to keep the floor up. I think the closest joists to the walls are about 250mm away.

[soundman]

If the room is stripped.
I'd remove the skirting & cut back the chip board flush to the wall.
(with a hand saw if necessary)
& replace with structrual ply wood.

The wall should be supported by its bottom plate.

Make sure you get some one reputable to do your membrane for the showre recess.
make sure you put in a floor waste.

Sounds like youve got a pollishing job???

[Giesse]

Well, the big question is... what supports the bottom plate? As far as I can see, the answer is... the chipboard floor. If I cut the flooring flush with the wall, the wall will then be held up by a loose edge of chipboard with nothing underneath.

[soundman]

Say the wall runs north / south the joists running east west will be "supporting" the wall the chip board will look like a spacer.


"Supporting" is a very loose term. Remember if this isnt a structural wall it just stands there and looks pretty. If you are standing next to such a wall you probably present more load on the structure than the wall.

If you want to be freaked out take the sheeting off a non structural wall and see how badly it flaps about.

[Giesse]

Actually, Doorstop, funnily enough, the house WAS very badly built! It's depressing, at times, just how bad it is. However, I see this as simply a challenge. I was brought up by my Dad to believe that there's nothing that can't be fixed, so hey, what the hell, let's just have a go! A stud here, a joist or noggin there. Whatever it takes. Wood is relatively cheap.

When you say "seal it and liquid flash it" - could you give me a little more information? I didn't realise that chipboard flooring required sealing...

And Soundman, the wall actually does run N-S. So do the joists. Parallel to the wall and about 250-300mm away from it. Bugger, thought I.

But I'm hoping it's not a structural wall. Actually, come to think of it, it's part of an extension and, as such, it's actually a double thickness wall. The other side of the wall is the end of the original house, and the side I'm working on is the start of the extension. I think the wall on the other side IS actually a structural wall, but the half on the ensuite side isn't. Which means that there is probably a joist or pair of joists running under the other half of the wall. In this house, it will be a surprise. Anything could happen, anything may have been done. I guess I won't know until I cut some holes in the floor and have a look.

[averack]

I am sorry if I am missing something here but can't you put some noggins between the joists to support the wall? There are pre-fab brackets available that would allow you to do it. I saw them used on This Old House to support laminated beams which were in the basement of a two storey house so there was no problem with the brackets holding the weight. They looked like those brackets you use for attaching pergola beams to the edge of the roof below the guttering or the side of the house. I was quite surprised that they could be used in that way but there you go.

Secondly, if the wall was structural and the flooring was rotted and supporting the wall then wouldn't the wall have sagged a bit and there would be cracking at the top of the wall?

[Giesse]

Well, as I said, I'm tending to think that the wall isn't structural. But I'll keep that in mind, re the noggin supports. It'll be easier to see what's possible once the floor is taken up, but it sounds like the general idea will be to cut the floor back right to the wall and if that means extra noggins, well, so be it.

The floor isn't that rotted (apart from the outer surface), it's just swollen on the edges and is very, VERY mouldy!

[soundman]

That that new revolutionry floating wall method.

[journeyman Mick]

Those "noggins" between the joists would actually be trimmer joists. I would put them in then remove the entire floor surface. The cheapest option that would still meet building code would be chipboard floor topped with fibro sheeting (make sure you follow manufacturer's guide for fasteners and adhesive) with a waterproof membrane over the top. In Qld (and probably in other states as well) leaking bathrooms are the leading cause of complaint to the building tribunal and have been ever since records were kept. I make a bout half my living from bathroom repairs and renovations. Don't try to do it on the cheap you are just throwing your money away!

[journeyman Mick]

Actually I gave some more thought to your job and the cheapest option would probably be a polished timber floor with a one piece fiberglass shower enclosure. I did a new bathroom like this almost 20 years ago and it's still fine but you must be very fussy about mopping up any water spills. Of course it goes without saying that you will put in a floor waste (legal requirement) and a glass door instead of curtains to minimise spills & splashes. A timber floor in a bathroom can work but you must be ever vigilant for spills or leaks. The best option is 18mm CFC (compressed fibro cement) next best option is sheet flooring with 6mm fibro topping. These to be covered with a properly applied waterproof membrane and tiled on flexible adhesive with flexible grout. Don't even consider vinyl unless it is industrial grade with welded joints, coved up the walls and running under the shower tray (not butted into it and then sealed as this will leak). Best of luck, and remember if in doubt as to how well you think you've put something together in a wet area just ask yourself if it would still work without that half a cartridge of silicone you just pumped in there. All joints and flashings in wet areas should still work without sealant, it should only be there as back up, if you're relying on sealant as the primary means of stopping leaks you're beaten before you've started.
Have fun,
Mick.

[Giesse]

Just a little question - how do you put in a floor waste when the floor is flat? Wouldn't you need to slope the floor all around towards the outlet?

You mentioned that it's a legal requirement - this must only be the case in Queensland, as I don't think I've ever seen one in Victoria.

[journeyman Mick]

Yeah, not sure about legal requirements in Vic. I know that the building act is supposedly unified across Australia but there are still differences and not being a plumber I couldn't even begin to guess how regulations vary from state to state. As far as putting a floor waste in a (hopefully) level timber floor, obviously it won't work as well as a floor with falls in it but it will stop your house from flooding if you start running the bath and then answer the phone etc. and forget about it. It also gives you somewhere to push the water to with a squeegee or mop. If you want to get really fancy, I have once sanded a slight dish into a floor to get it an ever so slight fall to the waste, but if it was my own bathroom I wouldn't bother. But even if it isn't a legal requirement where you are I wouldn't dream of building a bathroom without one, I mean it's only going to add somewhere between 10 and $50 to the price of the bathroom or laundry. It only needs to flood once to cause hundreds if not thousands in damage. Also on the subject of wastes and flooding, I don't know about elsewhere but in Qld any hot water system mounted inside must sit on a "safe tray" that is a metal tray with a waste connected, again to save you hundreds or thousands in water damage in the event of a mishap. Cheap insurance and worth doing even if not required. Have fun, be safe!

Mick