hardboard which way up?

19 Apr 2005
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United Kingdom
I'm about to tile my bathroom floor. Unfortunately i cant replace the floorboards as there is a shower tray fitted etc. Anyway the boards are pretty solid and all screwed down . There are some little gaps between them in places. I've had lino down previously and i was thinking of laying hardboard down to fill the gaps and then tile over the top of that. The question i have is....

which way up does the hardboard go? shiny side up or rough side?

i know thsi is similar to other posts but i cant find the answer to the hard board question.!!!
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On my aged, uneven and fairly gappy bathroom floor the tiler said no need to put down hardboard - he was using flexible tile fixative - so I didn't bother. Seems to have been OK - that was two years ago.
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Hi Dab,
Hardboard should be laid rough side up.
The rough surface provides a better key for the adhesive. Its also softer so when you run a scraper along the joints once laid it will take away any roughness. Most important you should nail with 1" annullar / serrated ringnails and if you lay rough side up then the final strike of the hammer drives the head of the nail into the soft surface thus countersinking it. This doesn't happen if you lay polished side up and then the nail heads show through your vinyl.
Is hardboard really suitable for this job?
It usually stretches in use.
If it is used, I think it should be conditioned for several weeks, before the tiles are laid.
show through your vinyl
im not planning onlaying vinyl. ceramic tiles

ok. now i'm confused.
one person says shiny up the other says rough.....

help :?: :?: :?:
dabaldie said:
im not planning onlaying vinyl. ceramic tile
If you're using ceramic floor tiles then you shouldn't use hardboard, should use exterior plywood (WPB)
We laid ceramic tiles in our bathroom about 4 months ago and used hardboard. Shiny side down so that the adhesive bonds to the hardboard and tiles. Make sure the hardboard is fixed firmly to the floor and doesn't move at all. This ensures a solid base that tiles will not move when fixed to it. If you ever choose to lift the floor tiles you remove them on hardboard without damaging surface underneath.
We have had success with this method.
have used hardboard several times in the past with sucessful results it just needs screwing down well, probably every 3-4". rough side up would be my prefered method, though if raising the floor height is an issue then, replacing the flooring with 22mm ply would be my favourite
Can anyone explain why it is necessary to put down hardboard - apart from Wheels' suggestion that it makes it easier to remove the tiles later?
Well the others have prove to me it's okay but I'm not sure because the way hardboard is made and not waterproof but I have found this from the flooring company.

Timber floors move. Whether it is individual floorboards or sheets of tongue and grooved chipboard, it moves. Movement underneath any fixed covering will cause problems as the timber will move at a different rate to the covering. This can cause gaps, tile lifting and even cracking. The existing timber floor can only be fixed where board meets joist underneath and these fixings are not generally enough to stop the floor moving. It is normally necessary therefore to fix a sheet covering of some kind, at short, regular intervals, to the existing floor.

We do not advocate the use of hardboard in these circumstances. Many people will tell you to soak hardboard overnight, lay and fix it when wet. When it dries, it shrinks back to stop it from bowing in the future....Our 30 years experience has taught us this does not work! The fixings used for hardboard are not substantial enough to keep the board tight. They either begin to pull out, allowing the board to move and bow, or, if larger headed nails are used, they work loose and can be felt, and even seen, through the covering you have installed. Our solution, as with most flooring companies these days, is the installation of 6mm plywood over the existing board. As mentioned above, this, together with the tiles, increases the depth of your floor, so it is better if the floor can run under the skirting.
thats as maybe, but the fact remains I have laid several floors on hardboard over floorboards, with no problems, the longest ago was about twelve years since at my mothers and those tiles are still down fine.
As you says as long you put down plenty of fixing I suppose.
thats as maybe, but the fact remains I have laid several floors on hardboard over floorboards, with no problems, the longest ago was about twelve years since at my mothers and those tiles are still down fine.

Hardboard still surviving?

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