bath installation - weight distribution

[Smifff37]

Hi newbie here, both to this forum, and to plumbing.

I recently installed a new shower bath with the help of a friend, who is an experienced handyman, but not a plumber. The bath is secured to the concrete party wall on two brackets, and at the tap end to the outer wall - presumably more to prevent movement than for support. The rear feet are placed on 3"x1.25" spreaders, stretched across two joists. My concern is the feet at the tap end. To allow us to install a pump between the joists, we cut away the a section of the chipboard floor, flush to the joists, so there is now a void where the feet should be standing. To get round this, the feet are standing on a 3"x1.25" spreader lying along a 4"x0.75" bearer, which in turn is lying along the 1.5" wide joist - the bearer being screwed to the joist, and the spreader also being screwed through the bearer into the joist. However the spreader, though lying fully on the bearer, is half on the joist, half off, while the bath feet are off centre on the spreader, about 1" inch from the edge on the side not lying directly on the joist.

My handyman friend assures me that this weight distribution is safe, but upon reflection I am feeling a little uncertain. I would welcome further opinions!

 

[dontknowitall]

Trying to picture your joists and bearers. If I've picture things correctly I'd be rather uncertain and would never leave a bath like that.

I am assuming that 2 or 3 of the bath feet are flat on the chipboard?

I feel the "spreaders" and "bearer" are not big enough. The 4" and 3" sound fine but the 1.25" and 0.75" sound very weak. 2" would be the minimum I'd use. Also, what happens if the bath were to move in a year or two? Would a leg collapse? I know a bath is not meant to move, but not everyone installs them securely. (Also, if the wall subsides a little it weakens the wall brackets.)

If you can, with confidence, jump up and down on those specific pieces without falling through to the floor below and there is space for the bath to move, you probably have no worries, but if you feel you might injure yourself from a collapse it won't be good enough. A bath full of water is a substantial weight and to me, five pathetic steel rod bath legs with plastic feet need all the support they can get!

I'm not sure you'll find anyone here willing to say "That's fine" because if something went wrong they might feel liable!

If it were me, I'd put some thicker wood supports in and maybe a noggin as well.

 

[Smifff37]

Yes, it is probably optimistic to expect anyone to say it is fine, particularly sight unseen.

To clarify, there are four feet. The back two are standing on lengths of 3"x1.25" laid on to the chipboard floor with the weight distributed crosswise across two joists. The front two are on standing a length of 3"x1.25" laid lengthwise along a length of 4” x 0.75" laid lengthwise along the joist.

The bath was a tight fit and at the moment there does not seem to be any movement.

My problem is that I have left it rather late to be having second thoughts - I have already tiled down to the bath on three sides, so I am very reluctant to rip it out and reinstall it. Ideally I would like to find a way of strengthening the existing installation.

 

[dontknowitall]

Presumably the back feet are on the 1.25" just to make things level? I assume you have the joist, then chipboard then 1.25" on top of that with the legs sitting on it? The joist and chipboard are going to do the work and if the legs are above the joist that's a bonus.

Presumably below the front feet is: joist (3" width?) with a piece of 4" x 0.75" laid along and on top of joist and finally with a piece of 3" x 1.25" laid along and on top of the 4" piece?

Hmm - just read the first post again ... 1.5" joist? I'm not a builder but that sounds too narrow to support the floor let alone a bath!! Not sure a building inspector would approve of that one.

But we are, where we are. So what I'd do is:

Put another decent piece of wood screwed properly into the joist to strengthen the joist. Use the joist and this new piece as support and pack it up with a single piece to get your level for the legs. Much better to use a 2" piece as opposed to two pieces of wood like 1.25" and a 0.75" on top. Use as long a piece as possible, preferably twice the width of the bath.

Again, not being a builder I'm not sure of my facts, but I'd suggest that if the joists are all 1.5" it might point to other faults and short cuts in the building. I hope not for your sake.

Hopefully someone else can help with this one, either to tell me I'm talking through my hat, or back me up, or make a better suggestion!

 

[Bernie2]

Have a look in the Bldg Regs under wooden floor structures.

They tell you quite a bit about floor loading. Certainly a bath full of water plus a person in it, must be getting on for something like 1/4 tonne weight in a small area.

I don't quite understand when you say the back leg batten is running across the joists so it is bridged over more than one joist to spread the weight. So although the batten is very thin and a minimum of 3" x 2" would probably have been better, it may hold.
But usually joists run the whole length of a room in the same direction, how come the front legs are standing on one joist?

 

[Smifff37]

Yes, the house is a piece of jerry built crap – I am becoming increasingly aware of that!

On the back legs, each foot is standing on a separate batten laid across two joists, whereas the front feet are on a single batten laid on top of a single joist.

The problem with screwing a piece of wood to the joist is that the builders have inconsiderately, and rather inexplicably, laid a gas pipe along it.

 

[bcp]

Was this installation a replacement for a bath that was already in situ? and is this a 'new-build' property? i.e. modern/ish housing as opposed to say Victorian or Georgian stock?

 

[REDSAW]

bet if the gas pipe goes you cant half blow some bubbles in the bath, stink abit too.