Bathroom floor - iroko T&G on top of 19mm P5 Green chipb

[efj]

I'm in the middle of our bathroom renovation and having read some previous posts on the use of green chipboard think I might have made a mistake with using it and wanted to double check ...

1940's semi with 5 m sq. bathroom floor. Lifted old T&G floorboards, as many were split, broken or smelled of pee. New plumbing just gone in.

I've laid T&G chipboard onto the joists, (didn't glue T&G ) but alot of 50mm screws. Boards run across joists and were cut down to length - so there are no chipboard joins in between joists.

I plan to lay T&G iroko on top of this apart from under the bath. Bath will just sit on top of the chipboard but will have a T&G iroko panel.

So my question should I lift the chipboard and replace with marine ply or will the iroko (once laid, sanded and danish oiled) be water resitant enough to prevent water getting to the chipboard and making it rot? Is there anything sort of treatment I can use on the chipboard first - to help increase it's water resistanceness?

One final question - I was going to secret nail the iroko to the chipboard. Is this the best way to fix it?

Any thoughts?

 

[mattysupra]

secret nail or glue would be better in any area that is going to try and move around alot. Either way you need plywood down. 4-6mm over the top of chipboard if glueing. Take it up and go direct over the joists or 18mm+ if secret nailing. I would be more worried about installing a wooden floor in a wet area tho. You will have problems. It is not recommended to lay wooden flooring in a wet area. The only wood flooring that has passed basic tests in wet area is engineered and bamboo.

 

[WoodYouLike]

efj
How wide are your Iroco boards? Also worth knowing is that Iroco contains a certain substance that will increase the drying time of any finish materials you apply to it.

 

[efj]

Guys, thanks for the responses.

Mattyspurra - I'll try and get a thin layer of plywood down on top of the chipboard.

WoodYouLike - the Iroko boards are not very wide 60mm I think off the top of my head. 4 packs of mixed lenghths 600 to 900mm - again off the top of my head.

We were thinking of using Tung Oil rather than Danish Oil as a finish. I'm told Tung Oil has a slower drying time. So with iroko's natural oils, do you how long it will take to dry per coat?

 

[WoodYouLike]

60mm should be glued down, not floating.
You could treat the Iroco with thinner first, that 'neutralises' the specific compound in the wood and then the oil dries only a bit slower than say on normal Oak.

 

[efj]

To show my ignorance here... what is the difference between glueing, secret nailing and floating? and how does the width of the board effect the method you use?

Is there any particulag glue I should be using? Remembering chipboard is the current sub surface. Though I hope to get ply down if I've time.

 

[WoodYouLike]

Glueing = fully bonding the wood to the subfloor
Secret Nailing = nailing floorboard in 45 angle to batten (at least 4cm thick) or joist
Floating = installing underlayment first on subfloor, installing floorboard 'floating' on the underlayment and glueing the T&G's.

60mm is too narrow to be installed floating, can cause too much movement.

hope this helps, or see more articles on installation

 

[efj]

Right.. got it... So my current options are:
1) Glueing - can this be done onto the chipboard?
2) Secret Nailing - but has to be into the existing joists, as chipboard is too thin at only 18mm.

Wish I asked here before starting this... with only a bucket flush pan at the minute not the best time to tell the mrs there's going to be a delay!

 

[WoodYouLike]

Yes, glueing can be done on chipboard. Use a product like B92 (Stycobond) or Lecol5500.
Nailing can't be done on chipboard, will split.
IMHO glueing is the best (and simplest option)

 

[efj]

WoodYouLike,

Thanks for all the advice.

For anyone following the thread or as matter of interest, found the following guide re how to glue boards....

http://www.hardwoodflooringimports.com/Downloads/GlueDownInstallationGuide.pdf

EDIT:
Can secret nailing into 18mm ply (i know it's not joists or 4cm thikck batons) be stupid?

Cheers.

 

[mattysupra]

With glue method i would recommend 4mm ply on top of plywood still. Been a few failed floors of late i have inspected where glued direct to chipboard. And as woody said about secret nail on to battern, you can also nail direct to plywood 18mm + thickness. When you nail into chipboard it blows a large hole in the back of the board you cant see as below floor. Leaves the nails with next to nothing to grip to.

 

[efj]

WoodYouLike,

Aplogoies this response is a couple weeks later!

I notice from some other posts that Osmo Hardwax Oil Polyx is recommended as a durable, waterproof finish. Would this be suitable for our bathroom iroko floor rather than the Danish or Tung oil as mentioned above?

efj.

 

[WoodYouLike]

HardWAxOil (Osmo or Blanchon) is a good product to use. But with most tropical wood types the drying time per coat takes a bit longer.

Always apply a thin layer, let it dry sufficiently (normally 8 - 10 hours, tropical 12 - 16 hours) and apply a second coat within 36 hours.

 

[efj]

Woodyoulike,

In trying to find where to buy the product I contacted Osmos UK and their technical advice for iroko in the bathroom was to try the following on sample pieces of wood first to see how it absorbs and looks:

Coat of Wood Protector some sort of waterproofing agent followed by either

Scenario1
Wood wax extra thin – to open up pores then
Polyx oil 2 coats

Scenario2
Just Polyx oil 2 coats

In your experience does that sound ok?

3 sample tins from them would only be £12 in total.

Cheers

 

[WoodYouLike]

Hi Efj

To be honest, we've never worked with the wood wax extra thin. But in our experience the first coat of HWO opens up the pores too - hence the fact you have to apply the second coat within 36 hours otherwise the open pores will have 'lift' their hairs - fibers - and you have to re-sand lightly.

If you use Osmo products and got their advice it's best to follow that in case things do get wrong - guarantees etc, you know