18mm or 25mm WBP... Solid Floor vs Step?!! Laid Tiles

[monkeysDIY]

Hi Gents,
I am ready to replace bathroom floor with WBP. Recommendation is 25mm… I think this is going to raise floor too high with my choice of tiles as current T&G is 18mm??? I obviously want to do it right first time… Can I use 18mm WBP and slip in lots of noggins 4” x 2”. Screwing every 150mm with 2 ½ zinc’ers??? I want to make sure I get a solid floor. My house is built 1987 and I believe joists are only 400mm apart. The bathroom itself isn’t huge (2200 x 1890)
Really appreciate support.
Thanks

 

[Richard C]

I've only ever used 18mm WBP with screws every 150mm & without any intermediate noggins; they are essential to support any board joints across the joists but will add little additional support otherwise. One of my efforts has been down over 3 years now without any problems at all.

Just as important as the base is to use a good trade quality flexible tile adhesive & grout; I only ever use BAL, it’s not cheap but you get what you pay for as far as these products are concerned.

 

[gcol]

Recommendation is 25mm

And why do you think that is?

 

[monkeysDIY]

Is it like Recommended Daily Intake? Cos I know I don't do all of those otherwise i'd have no time to work... what with running 3miles, walking briskly for 2miles, gym for max 1hour work out, drinking 2litres of water, eating 5 fruit or veg, all my Vitamins and NOT going over 2500 calories whilst avoiding Fats, Non Saturated Fats and Salt. TV should be limited to under 2hours and remember repeatedly doing a certain rhythm can cause RSI (& blindness in your case, if you believe the rumour GCOL) Anyroad, that was the reason for my post to get a sensible answer.....
Thanks

 

[Symptoms]

monkey - use 18mm thick stuff and drop in a few noggins, only to to keep your mind at rest, where the traffic will be greatest. The nogs will minimise/prevent any unlikely deflection of 18mm stuff which results in cracked ceramic tiles. Follow Richard's advice about supporting any joins in the ply by positioning these over joists (or a firm nog).

My pet hate is changing floor levels - they look wrong & if too high pose a trip hazard.

 

[monkeysDIY]

Thanks Symptoms
I am intending on using 4” x 2” for Noggins… stupid question… BUT do I lay 4” up or 2” up??????
Also my joists run from door to window (standard rectangle room) should I run sheets at 90 degree angle to this, creating one join approx half way into room…..
Thanks again

 

[Symptoms]

monkey - nogs long side vertical. 2200 x 1890 room means you'll have to buy two 8x4 sheets of ply. Cut both sheets to approx 2200 long then reduce their widths so the only join in your floor will be mid-point over a joist. If you can make the join under where the tub will be.

Oh, and screw the nogs in, don't nail (unless youv'e got an air framing nailer) - hammering nails into this type of structure WILL damage plaster ceilings below.

 

[Richard C]

Just so you’re clear; run the join between the boards along the centre of a joist not at 90 degrees. Always fit joists or noggins with the shortest side up (longest side vertical) for maximum strength. Always use screws as symptoms says; say, no 10’s long enough so at least 1/3 of the length enters the noggin & pilot drill first or the screw is likely to split the end grain of the noggin.

 

[monkeysDIY]

OK, I can run 1 sheet so that it almost is at bath edge BUT will be over a joist.
Shall I run noggins through centre of room.
I was going to run them under where to sheets met for support but guess I need to run them for strength
Should i screw through from other side into noggin...
Sorry but wanna be clear!
Pictures help me....
Thanks patient guys

 

[gcol]

Is it like Recommended Daily Intake? Cos I know I don't do all of those otherwise i'd have no time to work... what with running 3miles, walking briskly for 2miles, gym for max 1hour work out, drinking 2litres of water, eating 5 fruit or veg, all my Vitamins and NOT going over 2500 calories whilst avoiding Fats, Non Saturated Fats and Salt. TV should be limited to under 2hours and remember repeatedly doing a certain rhythm can cause RSI (& blindness in your case, if you believe the rumour GCOL) Anyroad, that was the reason for my post to get a sensible answer.....
Thanks

My what a wit!
25mm for peace of mind, 18mm if you like crossing your fingers.

 

[monkeysDIY]

Cripes GCOL.... You can safetly assume from my post that I dont "do" crossed fingers!!!!
25' it is them (you have read that right.... feet) I'll move bath into loft to be sure!!!!

Thanks again Guys

 

[Richard C]

Opps just re-read it!

 

[gcol]

Cripes GCOL.... You can safetly assume from my post that I dont "do" crossed fingers!!!!
25' it is them (you have read that right.... feet) I'll move bath into loft to be sure!!!!

Sorry the advice given at my free time to help you, did not meet with your hopes and dreams. If it feels more comfortable for you to hear what you want to hear then that's just fine and dandy. At this stage I couldn't care less whether your grout cracks and your tiles start to come loose. However, what I want you to accept is that any comment I made was to ensure that you end up with a good job. Sorry if you felt I meant something else.

 

[monkeysDIY]

No worries GCOL.
Thanks for your free advice.

"At this stage I couldn't care less whether your grout cracks and your tiles start to come loose."

I hope you are as considerate with your paid jobs as with your free ones.

Richard C... why the embarrassment.....

 

[Richard C]

No worries GCOL.
Thanks for your free advice.

"At this stage I couldn't care less whether your grout cracks and your tiles start to come loose."

I hope you are as considerate with your paid jobs as with your free ones.

Richard C... why the embarrassment.....

You obviously didn't see my original post which I then edited because I misread your reply; too much wine last night!

Don’t be so critical of GCOL, he has a lot of experience, far more than I; it’s just he has a very strong self-belief & can be a bit “direct” with his answers; as we all can at times!

Out of interest & to inject a little civility back into things;

Type “tiling onto wooden floors” into Google & this site will come up top of the list;

http://www.dunkleytiles.co.uk/advice-01.htm

This is a major tiling specialist in the south & is where I got the original recommendation of 18mm from some 4 years ago & is what I generally use. Ultimately it depends on the depth & spacing of the joists & their span which also dictates the amount of “spring” in the floor. I know there are many other sources that recommend 25mm WBP as a minimum & this should take care of all eventualities but in most its probably overkill. I would use 25mm if I considered it necessary on a particular floor but the biggest drawback is the huge difference in floor height it creates at the threshold. Ultimately it’s a personal decision; I’m a "relative" novice to tiling & may have been lucky but I’ve not had any problems so far.