Outline of my job - comments welcome

[jgw1]

Hi all,

Am tiling my floor this weekend with some slate tiles, I have not done this before so thought I'd check here that people thought my plans were sound.

Floor is 18mm chipboard, solid but with a bit of movement.

I want to use BAL Fastflex to glue 6mm Hardibacker to the chipboard subfloor then after this is dry screw it down. Because 6mm+18mm=24mm I can't use the Hardibacker without worrying about the pipes below so I have 1" drywall screws.

On top of this I want to add another layer of BAL Fastflex to the Hardibacker for the tiles.

How does this sound. Does the Hardibacker-Tiles adhesive have to be Fastflex or is that overkill (bit pricey).

Also do I have to tape the joins of the backer? I don't want to raise these is it can cause a problem?

Any advice greatly received.

[Grace'sDad]

Hi all,

Am tiling my floor this weekend with some slate tiles, I have not done this before so thought I'd check here that people thought my plans were sound.

Floor is 18mm chipboard, solid but with a bit of movement.

I want to use BAL Fastflex to glue 6mm Hardibacker to the chipboard subfloor then after this is dry screw it down. Because 6mm+18mm=24mm I can't use the Hardibacker without worrying about the pipes below so I have 1" drywall screws.

**I wouldn't bother with the extra cost of fastflex (unless customer is happy to pay. RSF would be ok, as long as you don't have excessive deflection in the floor - in which case you should address this physically i.e. sort out with extra noggins and screws 1st. Also - screw the boards down whilst still wet**

On top of this I want to add another layer of BAL Fastflex to the Hardibacker for the tiles.

**If you are going to use fastflex - there is little point in using hardibacker too - fastflex is good enough to use direct onto the boards (some may say different - but in my experience it's fantastic stuff for this!)**

How does this sound. Does the Hardibacker-Tiles adhesive have to be Fastflex or is that overkill (bit pricey).

Also do I have to tape the joins of the backer? I don't want to raise these is it can cause a problem?

**Tape is used as an expansion joint - limiting the potential boards movement transfering to the adhesive/tile - using fastflex I see little point in using it to be honest - but like primer - doesn't hurt to be on the safe side!**

Any advice greatly received.

Hope this helps! ( Oops - see ** replies above (my bad)

[jgw1]

Thanks for the quick feedback, I have bought the Fastflex and its sitting at home but not the Hardi.

So you think that Fastlflex onto the chipboard and tiles ontop of that?

jgw

[Grace'sDad]

How big is the floor area? Is it floating? If so it will need lots of screws putting down. I would be confident using fastflex direct - I have done this quite a few times. The only downsides to it - it will stick to the slate like superglue, so work very cleanly - keep a clean sponge and water to hand to sponge off excess. It also mixes quite thin, so don't expect to be able to build a thick bed. It does slump and spread, so spend time grading your slate carefully into groups of thickness, because back buttering is pretty much useless with fastflex - it will all come oozing out of the joints like cream cheese, very very very sticky cream cheese!

(PM GazTech (Bal technical guru) for more clarification on use)

[jgw1]

How big is the floor area? Is it floating? If so it will need lots of screws putting down. I would be confident using fastflex direct - I have done this quite a few times. The only downsides to it - it will stick to the slate like superglue, so work very cleanly - keep a clean sponge and water to hand to sponge off excess. It also mixes quite thin, so don't expect to be able to build a thick bed. It does slump and spread, so spend time grading your slate carefully into groups of thickness, because back buttering is pretty much useless with fastflex - it will all come oozing out of the joints like cream cheese, very very very sticky cream cheese!

(PM GazTech (Bal technical guru) for more clarification on use)

The total area is around 3m2 (pretty small bathroom), the floor is nailed into the joists below (ringed nails)- the joists are a little far apart for my liking (on top of a concrete floor) there is a fair bit of creaking which tells me that there is some movement.

I was going to use a thick bed solid bed trowel on the floor, say 5-6mm. How does that sound with the consistency?

Cheers for the tips (very friendly round here)

[Grace'sDad]

You'll have no problems with a 3sqm area. Just make sure you screw the boards down well. Any creaking will not affect your tiles - it will just anoy the customer . BAL recommend large format floor trowel for 30x30 onto floor, but I would use a 5-6mm normal trowel quite happily. (also makes the expensive stuff go further)

[jgw1]

Just to confirm, when you say screwing the boards down, you are talking about the existing chipboard not the Hardi which you are saying that I don't need.

Saves a bit of cash - that and I can take my Bal tanking kit back too as I'll be using Hardi to replace the decaying plasterboard walls.

[Grace'sDad]

Yup that's right - I mean the chipboard floor - not the Hardibacker.

[jgw1]

Thanks again!

I won't be priming the chipboard as I understand that this isn't recommended by BAL, is that right!

Sorry so many questions - its finally nice to find a forum that gives some answers.

[Grace'sDad]

No, don't prime - just make sure it's as dust free as you can.
(good forum isn't it? I've learnt loads on here. Most will be working today, most replies come through in the evening)
Happy to help, as they say in Asda

[jgw1]

Right all set, still not sure how I am gonna cope without a loo while doing the work. Might have to keep popping to local for use of facilities (including the bar).

One final thing is that the current floor is vinyl tiles, I can get them up but the the adhesive is difficult to remove. Do I need to remove the current vinyl tile adhesive.

If so I guess I'll have to use a chemical remover.

[MICK the Tiler]

If there is vinyl tiles to come up I would sheet over them with hardie backer. The adhesive that holds down the vinyl can affect the tile adhesive for the slate.

[jgw1]

Hi Mick,

So is that purely because of the vinyl tile adhesive and you'd not recommend Hardi if it wasn't there or because your a fan of Hardi?

[jgw1]

Right-o

Here are some pics of the current job:





The second shot is where I had to replace part of the chipboard subfloor with a bit of ply and some noggins.

Essentially from posting here I have four options.

1. Fastflex 6mm Hardi then flexible adhesive onto this
2. Fastflex tiles directly onto vinyl tiles
3. Fastflex tiles directly onto tile adhesive after vinyl ones are removed
4. Take the fastflex back, screw down 12mm ply and then fix tiles to this using flexible adhesive.

Any suggestions which way to go.

Floor is 18mm chipboard, total area 3m2, bathroom floor meets wood floorboards in hall which are 12mm plus 7mm underlay higher than the chipboard (19mm step up in total).

[grumpygrouter]

Pictures are good for us on here! Now we can see waht you are talking about.

If it was me, I would try to remove as much vinyl as possible to see what the rest of the floor is like first. As it is only 3m2 there should not be much movement in the floor. If it is solid and because you have already removed a chunk of chipboard, I would go with the 6mm hardie stuck with Ardex-flex 7001 and screwed as per instructions and then tile with 7001 or rapidset flexy. Is the toilet coming out?

[jgw1]

Yup the whole lot is coming out and the new bathroom fitted ontop of everything - so height is a bit of issue there so the pan fittings go together OK.

The chipboard itself is in good nick but the joists are ~450mm apart so things creak and there is a bit of movement.

How do you deal with the residual vinyl tile glue if I use Hardi. And can I use Fastflex - people here have said it is difficult to work with and I'm a novice.

I am going towards taking up the vinyl, screwing 12mm marine ply, then tiling onto this. Not sure what addy to use if I do this.

[MICK the Tiler]

Now I know what we are dealing with, here's what I would do.

Lift vinyl tiles
check the chipboard floor if it is at all crumbly or breaking down in any way it too must be removed and new 18mm plywood floor laid, sheeted with 6mm hardie backer, then lay the slate over this.

The reason the vinyl tile adhesive is a problem is that when you spread your glue to lay the slate it re-wets the vinyl adhesive then when all is dry the vinyl adhesive will crystalize under your slate adhesive causing a bond break and floor failure.

The reason I specify hardie backer on top of the plywood is this is a masonary product so is the slate so you have a masonary on masonary bond different movement stresses are avoided and would be a sound decision in rectifying the problem with the floor prep.

Even if the chipboard is sound I'd still be concerned with using it for a substrate for a stone product I would be inclined to remove it.

Others may have different ideas on this.

[grumpygrouter]

Yup the whole lot is coming out and the new bathroom fitted ontop of everything - so height is a bit of issue there so the pan fittings go together OK.

The chipboard itself is in good nick but the joists are ~450mm apart so things creak and there is a bit of movement.

How do you deal with the residual vinyl tile glue if I use Hardi. And can I use Fastflex - people here have said it is difficult to work with and I'm a novice.

I am going towards taking up the vinyl, screwing 12mm marine ply, then tiling onto this. Not sure what addy to use if I do this.

As the floor is only 3m2 and you look like you are using 12mm ply (wpb is fine by the way, Marine is very expensive) there will almost certainly be no movement in the floor. I would still go for Ardex-flex 7001 as an adhesive, nut you may get away with A Single Part Flexible as these are a bit easier to use. Bear in mind a standard setting adhesive will take around 16hr before it is set and solid enough to grout. The rapid setting stuff can go off a bit quick in the bucket for a novice. Fastflex will go off in less than 1/2 hour (though BAL reckon 45mins) The ardex stuff goes off quick too but I find it less messy to work with.

[jgw1]

Afternoon!

I thought that with the help I got here I should continue with more on the job.

At this stage it is more of a plumbing job but bear with me there WILL be tiling.

Here's what I am starting with...





Nice huh!

So my mate came round and we took out the sink..



And ripped out the wall, (dot and dabbed plasterboard) 25 years old and shot:



The plumbing ain't look to good either:





So we battoned out the wall



Added some sound insulation



And started boarding it with Hardibacker (note the soil pipe sound insulation and plastic membrane)



Sadly it had to stop there for the weekend... back to the day job...

Now two questions...

Should I tank my Hardibacker, I know that it will improve the waterproofing of the bath/shower, but can I use BAL adhesives ontop of the tanking paint?

Secondly Ardex 7001 has been recommended for the floor, over 12mm wbp plywood, is there a BAL equivalent? I have access to BAL at Topps but don't know of an Ardex supplier in Wimbledon.

All help much appreciated, more pics to follow - but only at weekends