Joists - how do I know if they're water-damaged?

(9 Posts)

Hi all,

We have had occasional leaks on and off from our shower in our upstairs bathroom, coming through to downstairs. Sometimes these are just a trickle, sometimes rather more. Lots of sealant, then more sealant, then more leaks and frustration. We're thinking now the problem is the shower screen area, so we are replacing the screen.

Anyway, how do we know whether the joists and the floor are safe? Will I be sitting in the bath one day and suddenly fall through the floor? Is this something we can check ourselves (how?) or do we need to get professionals in (who?).

lalalonglegs Mon 11-Mar-13 13:51:00

There's no fuss-free way of doing this. The easiest thing would be to open up the ceiling where the leaks have occurred and look at the joists: has the wood been damaged by the water? If you are planning to replaster, then this won't add much to the job (nothing at all if the plasterer has to take part of the ceiling down anyway).

No ceiling down - the water has crept through gaps and each time it comes through close to the wall. I'm hoping we're lucky and it has just gone through without sitting anywhere and soaking in, but how to know?

Forgot to say, we can see under the bath with the bath panel off - but what to look for?

lalalonglegs Mon 11-Mar-13 16:50:27

Can you remove any of the floorboards under the bath? If the wood is so wet that it is soft then you have a problem. Alternatively, if it is dry but very fibrous or crumbly, that is also not a good sign. It's more about touch than visible signs.

PigletJohn Mon 11-Mar-13 16:50:29

if the flooring is chipboard (which is rubbish, made of sawdust and glue) then it will be ruined. It will swell and go soft and weak, and may fall apart in flakes. You or your bath may fall through it at an inconvenient time. Budget for taking the floor up and replacing it in 18mm WBP ply.

Once the floor is lifted, you will be able to look at the joists and poke them with a chisel ended screwdriver (never poke wood with any round pointed object as the next person will think you have woodworm)

It is possible to replace bathroom flooring in sections, without taking the bath out, but very fiddly and will take much longer so cost much more.

I like to treat bathroom joists with Cuprinol Green Wood Preserver (or 5-star) whenever they are exposed, to discourage future attacks.

Taking up the flooring will also allow it to dry out faster. Moist, warm timber rots very fast.

Thanks for the responses.

Flooring is old floorboards (Victorian house, I guess the joists and boards are original).

Will have a look at the floor later.

PigletJohn Mon 11-Mar-13 16:59:37

taking the bath panel out, and leaving it out, will allow air circulation to dry it out faster. You can have a fulfilling afternoon sweeping, hoovering and mopping under the bath. It will be quite dusty. You will also be able to see where the water is going.

It can be useful to drill holes through the ceiling under a leaking bath so the water escapes quickly without accumulating.

So I've had a grope around under the bath....

I think I'm not going to fall through the floor any time soon. One board is a bit rotten at one spot, but isn't supporting anything. There are big gaps in the flooring under the bath and I suspect the water found its way through to downstairs fairly quickly, without sitting on the wood and rotting it.

On trying to locate the joists though, I managed to knock a small piece of loose floorboard through one of these gaps into a black hole... blush Who knew there was such a distance between the floor and the downstairs ceiling? confused Thought we were never going to see it again but DH lay on the floor and rummaged in the black hole and managed to locate it. I shouldn't be allowed near anything that requires delicacy of movement!

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