Treating Bathroom Floor Joists from water

likelex · 23 Nov 2013

Hi guys, I've just got a quick question about the best stuff to use on timber floor joists to protect from water in our bathroom. We are redoing the whole room from scratch (victorian semi) and are about to pull up the old floorboards which we will relay closer together to lose the gaps and then sand, dye and varnish.

While its all up I thought it would be a great idea to treat the floor joists with something as we have got a freestanding roll top bath which I am sure will see some splashes hit the deck from time to time.

Our old shower leaked over a period of time and did cause some black(mould?) staining which has all dried out now and not rotted thank god but I am cautious now it will all be so exposed (previously had tiles laid on ply covering the boards) that it will be subjected to a higher moisture level and like I say some actual water now and again.

What is the best treatment for the joists please? And would it also be an idea to treat the old boards or will the waterproof varnish be enough to seal the boards themselves. We are planning to use either Osmo Poly-X Varnish or Liberon High Resistance Floor Varnish. Ronseal Diamond Hard we have in our living room is just ****** and has worn off in high traffic areas within a year.

Any advice greatly appreciated!

Many thanks

J

foxhole · 23 Nov 2013

You need to seal between the boards and at skirting to prevent any water reaching the joists.

likelex · 23 Nov 2013

foxhole said:
You need to seal between the boards and at skirting to prevent any water reaching the joists.

Hi foxhole - sure, but what's the best thing to use? I just thought it would also be prudent to protect the joists from water as somewhere down the line water is bound to leak through a gap..! Just wondered what kind of product is best to brush onto them before relating the boards?

Cheers

JohnD · 23 Nov 2013

I use Cuprinol wood preserver which protects against rot. It is not the same as their garden priducts which are usually water-based and leave a waxy coloured stain.

foxhole · 23 Nov 2013

likelex said:
foxhole said:

You need to seal between the boards and at skirting to prevent any water reaching the joists.

Click to expand...

Hi foxhole - sure, but what's the best thing to use? I just thought it would also be prudent to protect the joists from water as somewhere down the line water is bound to leak through a gap..! Just wondered what kind of product is best to brush onto them before relating the boards?

Cheers

Unless you plan on flooding the place regulary protecting joists is pointless.
Joists will rot in the wall where you can't get to with preservatives.

JohnD · 23 Nov 2013

drip

drip

drip

likelex · 26 Nov 2013

Well of course it would not be my intention to flood the bathroom regularly or at all for that matter but I just wanted to take precautions so as to minimise damage to the joists should water leak through the boards (despite sealing the gaps) once the floor is nailed down I'm not wanting to ever get under it and the ceiling beneath (kitchen) has just been boarded and skimmed...

I have seen and been in plenty of victorian bathrooms with original floorboards exposed, just wanted some friendly advice on how to protect the wood.

likelex · 26 Nov 2013

foxhole said:
likelex said:

foxhole said:

You need to seal between the boards and at skirting to prevent any water reaching the joists.

Click to expand...

Hi foxhole - sure, but what's the best thing to use? I just thought it would also be prudent to protect the joists from water as somewhere down the line water is bound to leak through a gap..! Just wondered what kind of product is best to brush onto them before relating the boards?

Cheers

Click to expand...

Unless you plan on flooding the place regulary protecting joists is pointless.
Joists will rot in the wall where you can't get to with preservatives.

Well not pointless if you have a roll top bath in the middle of the room nowhere near the edges/walls... Pretty sensible to protect the joists beneath I'd say? Obviously you can only do the bits you can get to but surely that's better than leaving them totally exposed to potential water damage/rot!

foxhole · 27 Nov 2013

Does not matter where the bath is placed water will run to walls and down if unsealed.

gritmonkey · 27 Dec 2013

likelex said:
foxhole said:

likelex said:

foxhole said:

You need to seal between the boards and at skirting to prevent any water reaching the joists.

Click to expand...

Hi foxhole - sure, but what's the best thing to use? I just thought it would also be prudent to protect the joists from water as somewhere down the line water is bound to leak through a gap..! Just wondered what kind of product is best to brush onto them before relating the boards?

Cheers

Click to expand...

Unless you plan on flooding the place regulary protecting joists is pointless.
Joists will rot in the wall where you can't get to with preservatives.

Click to expand...

Well not pointless if you have a roll top bath in the middle of the room nowhere near the edges/walls... Pretty sensible to protect the joists beneath I'd say? Obviously you can only do the bits you can get to but surely that's better than leaving them totally exposed to potential water damage/rot!

Better idea is to prevent the water reaching the joists in the first place!
TBH I wouldn't be worried about the joists getting wet, I'd be more bothered about finding the ceiling below on the floor of the room below!
If you're really that bothered then have a wet room firm in to do a proper job.

JohnD · 27 Dec 2013

drip

drip drip

drip drip drip

moisture in and under bathroom floors is extremely common.

likelex · 28 Dec 2013

It's impossible to get a straight reply on this forum!

I have seen (both in person and on the web) plenty of bathrooms where the sole flooring is simply the subfloor - either reclaimed or original floorboards. Does anyone know what precautions one can take to seal said floor and joists beneath (in the event of water getting through any gaps onto joists) in terms of treating the wood or providing a seal to the surface. I am planning on filling the gaps in between the boards so I will not get eater falling onto the ceiling beneath. We have had the use of only our freestanding bath for over 2 months now as we haven't fitted shower cubicle yet, no spillages yet and brand new kitchen ceiling beneath, old original 100yr old untreated floorboards in bathroom - it's simply a precautionary measure I'm after!

Any sensible suggestions welcome.. We will be keeping the floorboards for the style and look of the bathroom so there are no options on that.. Just need to know how to protect them and the wood beneath..

Many thanks!

likelex · 28 Dec 2013

PS. I don't want a wet room or I wouldn't be on here asking these questions. I am more than capable of doing a proper job myself, just after some friendly advice. Thanks.

foxhole · 28 Dec 2013

likelex said:
It's impossible to get a straight reply on this forum!

I have seen (both in person and on the web) plenty of bathrooms where the sole flooring is simply the subfloor - either reclaimed or original floorboards. Does anyone know what precautions one can take to seal said floor and joists beneath (in the event of water getting through any gaps onto joists) in terms of treating the wood or providing a seal to the surface. I am planning on filling the gaps in between the boards so I will not get eater falling onto the ceiling beneath. We have had the use of only our freestanding bath for over 2 months now as we haven't fitted shower cubicle yet, no spillages yet and brand new kitchen ceiling beneath, old original 100yr old untreated floorboards in bathroom - it's simply a precautionary measure I'm after!

Any sensible suggestions welcome.. We will be keeping the floorboards for the style and look of the bathroom so there are no options on that.. Just need to know how to protect them and the wood beneath..

Many thanks!

Just because you have seen lots of people doing stupid things does not make them a good idea.
You would need the joists covered with a dpc sheet before boarding them to prevent water egress below.

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Treating Bathroom Floor Joists from water

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