Tiling on plywood - do i need noggins?

[richardadc]

For the amount of hassle you are going to be up against, I would lay a vinyl floor such as karndean or Amtico.

They are better suited to bathrooms in any case.

Thanks but either way the floor is going to have to be replaced. A fair amount is rotten and some has been cut between the joists.

The question at the moment is, is this something i need to get someone in to do or will my original idea of using 6x2 noggins work.

Maybe I should post this in the flooring forum.

 

[Richard C]

Maybe I should post this in the flooring forum.

You won’t get any better response in Flooring, all they will try to sell you is more vinyl, wood or some other overlay with warnings about levels & damp etc. they probably won’t have much to say about the structural integrity of your floor as, unlike tiling, it’s not critical for that type of floor covering; any flex in the floor beyond the adhesive/grout tolerance & your tiles will fail. Building Forum would be equally as appropriate as Tiling but you will probably get a similar response & I lurk in both.

either way the floor is going to have to be replaced. A fair amount is rotten and some has been cut between the joists. The question at the moment is, is this something i need to get someone in to do or will my original idea of using 6x2 noggins work.

It’s very difficult to give precise advice based on a line diagram & descriptive & your floor condition/structure seems marginal for a tile base but I’ve done my best to give advice on that basis. Your idea maybe sufficient given it’s at the edge of the room but if the joists are suspect & your over boarding marginal thickness floorboards, maybe not. I think you have a good grasp of what is really required you just seem to be shy to commit to the work & bringing in someone else in may not make things any better. Based on the info you’ve given, you’ve been given good advise on what you need to do to ensure your tiling doesn’t fail but you seem intent on your chosen path; your call really.

 

[bathstyle]

Can't you replace the rotten boards? even if they go under your wall, just replace one at a time to maintain support for your wall.

I rip up a lot of floors and stud walls not on joists is commonplace.

a few noggins sounds sensible if you go that route but your replacement flooring will need to be the same thickness as the existing if you are re boarding.

 

[richardadc]

Thanks both. I really appreciate the advice you're giving. I just need a bit more clarity on what exactly is being suggested i.e. If you say to me what i'm planning is likely to fail then i'l admit defeat. If it's a case of your idea is the belt and braces and mine is 90% fine then i'm ok with that.

Bathstyle, regarding replacing the floorboards the reason why i've changed my mind on doing this is that i'm going to end up replacing 50% of the boards (due to some rot and cuts). The floor boards are also 90mm wide which doesn't seem to be a standard size so it'll make it even harder to replace. And what with them only being 16mm it doesn't sound like it's a good base to re-board on anyway. All in all it sounds like i'd be doing all that work for a pretty poor job.

My plan is/was to remove the floorboards and fit 6x2 noggins every 40cm going from the end joist in the bathroom to the first joist in the bedroom. I'll fit this by skew screwing where possible. In these noggins i'll do two 1 inch notches out of the top of the noggin for the two pipes to rest in. The noggin length will be 40cm with 25cm of this noggin on the bathroom side and the rest on the bedroom side. I'll then board all of this with 25mm WBP plywood screwed every 15cm into the joists. I'll also have 6x2 noggins by the door and where the two plywood board join.

On the bedroom side rather than use the 1x1 piece of wood to rest the floor board on i'll fit additinal 4x2 noggins to the 6x2 noggins to screw the floorboard to.

Now, if this is a stupid idea then please be completely blunt and say that. I need you to be hard on me I'll then leave it a while until i can get it done the other way.

As jor the 8.5x1.5 joists that are currently in place, they show no signs of rot or other problems.

 

[bathstyle]

OK, quick question.....you are removing the old 15/16mm floorboard which run under your partition wall and you want to replace with 25mm ply? How is the 25mm ply going to fit under your stud wall and how will you be supporting your stud wall whilst this work goes ahead?

Oh yeah, you mention you're on a budget, take a look at the cost of a sheet of 25mm ply.

 

[richardadc]

OK, quick question.....you are removing the old 15/16mm floorboard which run under your partition wall and you want to replace with 25mm ply? How is the 25mm ply going to fit under your stud wall and how will you be supporting your stud wall whilst this work goes ahead?

Oh yeah, you mention you're on a budget, take a look at the cost of a sheet of 25mm ply.

Under the wall i'm going have a 16mm piece of wood (the same as the removed floorboard) running the length and suppored by the noggins i put in place. The ply will end by the wall. As for supporting the wall while this work goes ahead, i'm only going to remove 4 floor board at a time and then fit the noggin underneath before going on to the next one. So the wall will remain supported throughout.

Regarding budget i've worked this out to be £1.3K which includes everything from a tile marker to the bath suite. The plywood comes in at £86 for an 8x4 and an 8x2 sheet inc delivery.

 

[JohnD]

I did a floor recently in 18mm ply (bit cheaper than 25mm but very satisfactory if you nog under any unsupported edges) far better than the old chipboard.

I used a hardwood-faced ply from Wickes, £35.08 per 8x4

 

[Richard C]

I’m rather lost as to weather you are over boarding or laying a new ply floor. If replacing the floor, 25mm is the BS & adhesive manufacturers recommendations but it’s often quiet feasible to use 18mm or 22mm WBP in low load/traffic areas such as bath shower rooms, it depends on the joist size/pitch/span & each floor needs to be individually assessed.

For bathrooms & especially when tiling, you should only ever use WBP ply never standard ply, it doesn’t use waterproof adhesive to bond the veneers & will delaminate if water gets in; even tile adhesive/grout could set it off. As for the cost, it’s insignificant in comparison to the total cost of sanitary ware, taps, showers & tiling materials; even more so if it goes wrong & you have to rip it all up again to do it properly.

 

[richardadc]

I’m rather lost as to weather you are over boarding or laying a new ply floor. If replacing the floor, 25mm is the BS & adhesive manufacturers recommendations but it’s often quiet feasible to use 18mm or 22mm WBP in low load/traffic areas such as bath shower rooms, it depends on the joist size/pitch/span & each floor needs to be individually assessed.

I'm laying a new 25mm WBP plywood floor. I gave up on replacing the 16mm floorboards when i found out they were damaged more than expected and that you said the depth of them is quite poor.

I think i've decided i'm going to go ahead with my idea and risk it as it doesn't sound like what i'm doing is that unsafe. If people are resting the joins of their plywood on 4x2 noggins i should be fine in using 6x2 noggins to support the plywood by the end of the wall. At least that's my thinking

 

[Richard C]

So full circle & were back to the start of your thread & my earlier posts ; if you’re using 25mm WBP, I’m certain it’ll be fine unless your joists are shot & you start jumping up & down next to the wall; but why would you.

Remember to seal the underside (not top side) & edges of the ply with acrylic primer before laying & don’t forget noggins under the unsupported edge (4 x 2 will be fine)

Were on page 3 now &, without checking, I’m sure I’ve already given you the lecture about quality/choice of tiling materials, reading tiling sticky & archive posts etc.

Come back if you need more.

 

[richardadc]

So full circle & were back to the start of your thread & my earlier posts ; if you’re using 25mm WBP, I’m certain it’ll be fine unless your joists are shot & you start jumping up & down next to the wall; but why would you.

Yep, pretty much. The lack of a support by the wall was a bit of a shock for me

Remember to seal the underside (not top side) & edges of the ply with acrylic primer before laying & don’t forget noggins under the unsupported edge (4 x 2 will be fine)

Were on page 3 now &, without checking, I’m sure I’ve already given you the lecture about quality/choice of tiling materials, reading tiling sticky & archive posts etc.

Yep, I think i've read just about every post on this forum.

Thanks again - i'll let you know how it all goes.