Tiling on plywood - do i need noggins?

[richardadc]

I'm about to remove the floorboards in my bathroom and replace with 25mm plywood. Due to the size of the room i'm only going to need 2 pieces of plywood and as such the board will be following along the joists (and as such is never unsupported). The gap between the joists also seems to be about 40cm.

Due to this am i correct in saying they'll be no need to use noggins?

Please see attached image for clarification - the blue and red boxes indicate the two plywood boards.

Untitled

• richardadc
• 2 Jun 2011
• 1

 

[Richard C]

Unfortunately not; you must use decent size, well fitted support noggins between the joists to support the board edges where they meet in the centre of the room or it WILL crack. You don’t actually show any but I’m assuming there are joists at the perimeter edges of the room (top & bottom)? Noggins are not normally necessary on the two unsupported edges on the perimeter across the joists (left & right) unless across a door threshold or an area subject to any sort of loading/traffic.

You must use WBP ply, not ordinary ply & seal the underside & edges with an acrylic/SBR primer; do not seal/prime the top tile surface. Fix down with screws every 150mm into the joists/noggins

Only use quality trade adhesive & grout of the correct type for your tiles, the cheap DIY stuff is mostly crap. Read the tiling forum sticky & archive posts to avoid making disastrous & potentially expensive mistakes. What are you doing with the walls?

 

[richardadc]

Thanks Richard. I think i understand why now.
There is also a door threshold on the right so i'll put noggins in that area too. I've also now updated the image to include the new plan - the yellow indicates the noggins and the orange square indicated the area to be tiled.

As for the noggins is there a specific size and type of wood i should be using?

Untitled

• richardadc
• 3 Jun 2011
• 1

 

[Richard C]

As for the noggins is there a specific size and type of wood i should be using?

Plain old 4” x 2” sawn will do. Make sure it’s well dried (to avoid any shrinkage), the noggins are tight fitting between the joists, position so the boards meet in the centre & put 3 layers of glass fibre overlapping mesh (plastering tape will do) tape over the join; use screws (10’s or 12’s) of a suitable length, don’t use nails.

What adhesive/grout do you intend to use? it's important you get it right & use only quality trade products, the cheap DIY stuff is generally crap

 

[82much]

WBP Ply is this what is called exterior ply please?

 

[Richard C]

WBP Ply is this what is called exterior ply please?

WBP = Weather (water) & Boil Proof; yes it's exterior grade ply.

 

[82much]

thanks Richard - I can breathe a sigh of relief as that is what has been put down.

 

[richardadc]

As for the noggins is there a specific size and type of wood i should be using?

Plain old 4” x 2” sawn will do. Make sure it’s well dried (to avoid any shrinkage), the noggins are tight fitting between the joists, position so the boards meet in the centre & put 3 layers of glass fibre overlapping mesh (plastering tape will do) tape over the join; use screws (10’s or 12’s) of a suitable length, don’t use nails.

Ok great, i take it this is correct - http://www.gards.co.uk/product.php?xProd=484&xSec=124

What adhesive/grout do you intend to use? it's important you get it right & use only quality trade products, the cheap DIY stuff is generally crap

I'm going with BAL Single Part Flexible for the adhesive from http://www.tileexperience.co.uk/ProductDetails.aspx?ProductID=159 which i'm going to use on the floor. I haven't yet decided if i'm going to use this or the 'white star' tub for the wall tiles. For the grout I haven't yet decided - please feel free to suggest one.

 

[Richard C]

http://www.gards.co.uk/product.php?xProd=484&xSec=124[/QUOTE]
You don’t really need pressure treated timber but it’ll do; plain old sawn is cheaper.

I'm going with BAL Single Part Flexible for the adhesive from http://www.tileexperience.co.uk/ProductDetails.aspx?ProductID=159 which i'm going to use on the floor.

That should be fine but what type of tiles are you laying?

I haven't yet decided if i'm going to use this or the 'white star' tub for the wall tiles.

What size are the wall tiles? You should be using powder addy on anything larger than around 250 x 250 x 8mm. What are you tiling onto?

For the grout I haven't yet decided - please feel free to suggest one.

Superflex for the floor; dont use white or light colours or it’ll look very grubby in a very short space of time. Microflex for the walls but,again, what type of tiles are you laying?

 

[richardadc]

Thanks for the info. Just out of interest what colour grout would you recommend for a light being floor tile? I'm tiling on to plasterboard which I will tank.

The wall tiles are ceramic 250x200. I'm not sure on the depth.

 

[Richard C]

I assume you meant beige? Grey goes with most tile colours but with beige perhaps a slightly darker contrasting beige/brown & sometimes dark brown will go really well, it depends; but white does not do well on floors in the longer term even if you seal it.

You should be OK with a decent flexible tub ready mix (White Star) with tiles that size. Sorry I've edited a mistake on my last post; it should have read 250 x 250 x 8mm. I usually consider switching to powder adhesive around that size but it depends on weight.

Bit slow, only just noticed you have another thread for the walls.

 

[richardadc]

Thanks Richard - you've been really helpful!

 

[richardadc]

After a bit of investigation this weekend to make a decision on materials to buy I’ve realised that removing the floor boards and laying down ply isn't really feasible in the time and budget contraints. The main reason for this is that i assumed the left wall would have a joist under it but this is not the case. Running some noggins between the two joists isn't possible either as there is pipe work running parallel to the wall.

As such i was wondering if fixing down by 16mm T&G floorboards with some 60mm screws (and replacing any rotten sections) and then overboard with 'no more ply' would be acceptable?

 

[Richard C]

After a bit of investigation this weekend to make a decision on materials to buy I’ve realised that removing the floor boards and laying down ply isn't really feasible in the time and budget contraints. The main reason for this is that i assumed the left wall would have a joist under it but this is not the case. Running some noggins between the two joists isn't possible either as there is pipe work running parallel to the wall.

You’ve sort of lost me a bit there.

As such i was wondering if fixing down by 16mm T&G floorboards with some 60mm screws (and replacing any rotten sections) and then overboard with 'no more ply' would be acceptable?

16mm T&G floor boards? T&G flooring is usually 18mm! Is this going to be over the top of existing floor or is it replacing it? What sort of T&G, not chipboard I hope! I don’t normally use NMP for over boarding; 12mm WBP, Hardiebacker 500 or even 250 would be better IMO. I can’t see how doing this is going to be cheaper than replacing the floor with WBP?

Taking shortcuts is a false economy; your floor must have no perceivable flex or you risk tile failure & that will end up a lot more expensive than the time & a little additional expense involved in preparing the floor well in the first place.

 

[richardadc]

The problem is the wall at the bottom of the picture above (which is parallel with the joists) is resting on the floor boards going into the other room rather than a joist. This means if i want to remove the floor boards and lay plywood instead I’m going to need to have something by the wall for the plywood to lay on. The only way to achieve this is to lay noggins going from the last joint in the bathroom to the first joist on the other side of the wall. The problem with this however is pipe work running parallel to the wall in this area so I can't achieve this without getting a plumber out and re-routing the pipe work.

At the moment the floor in the bathroom does creak but I’m guessing if i screw this all down (it's just nailed in at the moment) this will solve this. It is also definitely 16mm T&G softwood timber.

As for not using NMP could you please let me know why? I know it's all marketing but NMP seem to suggest it's a direct replacement for plywood and i can't say I’ve seen a bad word said about it. Is it a case of NMP doesn’t offer structural strength buy plywood does?