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Complete Bathroom Tiling - Preparation

Discussion in 'Tiling' started by Schmill, 17 Jun 2010.

  1. Schmill

    Schmill

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    Just after some overall tips please guys I've read so much, plenty of it conflicting with each other, some saying that things should never been done, some saying that things are fine, and some saynig that some things are overkill for domestic installations - lol

    So, I've taken out the old bathroom suite; bath with overhead powershower, sink & toilet, and removed the full wall tiling.
    This was onto plasterboard, which I have repaired any damaged sections of and cleaned all the old adheisve / grout etc from.

    I cannot realistically change the plasterboard as it forms one skin of a 'honeycomb filled prefab wall' from the looks of thing, hence the repairing.
    I can also not 'overboard' it with anything, as doing so will decrease the bathroom size such that the bath won't fit - lol The walls of the bathroom are 'just' far enough apart to take the bath.

    The tiles that I will be fitting (Homebase Verona )are 8mm thick, 25cm x 33cm tiles.

    The plasterboard is of the bevelled edge type, which looks like it had a jointing tape fitted over, and then plaster applied, (not over the full wall, just the joints).

    Do I need to replace this jointing tape and apply a plastercoat, or will tile adhesive just fill this slight 'dip' ?

    Everything I had read also said about priming 'stripped back' plasterboard with a 5:1 water:pva mix, so I have applied that to all of the plasterboard.

    However I have now read (in some places) that this shouldn't be done, and yet I've read in other places that it MUST be done... which is correct? If I shouldn't have done it will a damp sponge take off the pva mix (although it seems to have soaked into the plasterboard).

    I've also read about 'tanking' the plasterboard. Some say in a shower area this must be done, others say that in a domestic environment it is unneccasary overkill. Obviously when I have stripped out the old tiling there is / was no tanking behind it.

    Is tanking needed? How / what do I need to do it if so? Roughly what cost?

    I will be refitting a toilet sink and bath as before, and also a pumped mixer shower, not sure if this makes the slightest difference, but wanted the information to be here :)

    Lastly, as we have cavity walls the bathroom window is 'set in' and there is a ledge all round the window. Previously this was tiled, but when trying to remove the tiles I pulled off the old plasterboard strip that was 'dot-n-dab'ed to the top of the alcove. I am going to replace it with new plasterboard, but can I just afix this to the 'dabs' that are still attached to the top of the alcove, or do I need to do something different to ensure it doesn't fall down with the weight of the tiles on it? (It did have tiles on before)

    Sorry for the long post, but I thought I was all ready to start refittting the bathroom and tiling, and now I'm right back into a dilema about whether I've done what needs doing preperation wise :(
     
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  3. Richard C

    Richard C

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    Yes
    No not if your tiling but you need to rough fill voids as you want the tiling base as flat as possible.

    Your probably better using powder cement based adhesive for that size tile, you can rough fill with that immediately before tiling but the plaster will need priming to avoid a reaction between the Gypsum in the plaster & cement in the adhesive.
    http://www.bal-adhesives.co.uk/products/prime-apd

    PVA will be generally be used if your going to re-skim with plaster but applied just before skimming & skim when tacky. Don’t ever use standard PVA over a tile base;
    http://www.ultimatehandyman.co.uk/forum1/pva-why-you-shouldn-t-use-it-as-a-tiling-primer-t168.html

    If you were to see the state of some of the plasterboard (even Moisture Resistant) I rip out of bath/shower rooms you would not say it was overkill; depends how long you want it to last 2-4 years or a minimum of 10 years. Better still use waterproof backer boards, no tanking necessary. Tanking product
    http://www.bal-adhesives.co.uk/products/wp1-coating
    or you can use a membrane.
    A bit of advice; read the Tiling sticky & the Tiling Forum archive posts which will answer almost all of your questions; there are several trade contributors & we all generally sing from the same hymn sheet; this one may be a good place to start;
    http://www.diynot.com/forums/viewtopic.php?t=225485

    Also Building Forum for shower pump installs; come back with specifics if you need.
     
  4. Schmill

    Schmill

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    Thanks for the response Richard, if somewhat depressing as it means I am not yet reading to start tiling, but better to find out NOW rather than later :confused:

    Without some kind of massive teardown affecting not only the bathroom, but also the neighbouring rooms I can't change the backing boards, so plasterboard it has to remain.


    So from reading the other posts you linked to, and what you have written I need to;

    - get some more of the 'paper tape' to put over the plasterboard joins, and then level off with some plaster to the same level as the rest of the board face, (so just plastering the bevelled join, not the board face).

    - wipe down and try to remove as much of the PVA solution that I put on the boards as possible.

    - prime the whole thing with something like the BAL APD Prime to stop any nasty reactions.

    - make sure the adhesive I have is a 'cement powder' based one, (presumably grey), rather than some other type (which I guess is the whiter ones?). Does this have to be one of the waterproof types, or is that only relevant for the non-cement-powder ones? (Of course I am hoping no water will be getting to the adhesive anyway!)

    I'm presuming that this is NOT applied over the whole bathroom, just around the wall near the top surface of the bath, and also across the entire area that will get regularly wet from the shower?
    Also, (and I'm sure this is a silly question, but...), the membrane, or kits don't then effect the hanging weight capability of the plasterboard? I would hate to put my tiles up, just to have them come back down complete with membrane on the back, (although that might be handy for putting them back up!)

    Many thanks :)
     
  5. Schmill

    Schmill

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    Sorry to be a royal pain in the backside, but of these 2 primes which would I need, and what is the difference, (and presumable reason for the price difference?)

    BAL Primer

    BAL Prime APD

    Presumably this is the tanking kit:
    http://www.toppstiles.co.uk/tprod3073/section885/BAL-WP1-WATERPROOF-SHOWER-KIT.html
    If so ouch :( thats gonna hurt...

    Is there an advantage / disadvantage to using a membrane, and would that work out cheaper?


    Finally... (for now at least!), does the cement powder based adhesive 'go off' with age? I think I might have some in a bag in the garage, will that be ok as long as it has been kept dry, or does age 'kill' it in some way?
     
  6. Richard C

    Richard C

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    Not paper tape, use GRP reinforcing tape. You can use finishing plaster (but don’t use base plaster) & you’re not looking for a smooth finish; but if you plan to use cement powder adhesive for the tiles (which you should be) use that to rough fill just before you tile.

    If you’ve already PVA’d, I would only be concerned about the wet areas; PVA will affect tile adhesion but once it’s gone off, it’s unlikely to be a problem except in wet areas.

    Only necessary if your using cement powder addy which would be a good idea with the size/weight of your tiles.

    Usually greyish but colour is irrelevant; cement addy comes in a bag which you have to mix with water but be careful how much you mix in one go as it only remains usable for around 30 minutes. Tub addy is pre-mixed in a sealed tub & usually white.

    Only use waterproof addy; both cement & tub addy can be waterproof but it’s important you understand “waterproof” in the right context. Unless it’s an expensive epoxy based addy/grout, waterproof only means it wont disintegrate when it get wet, it will still absorb water/moisture which is why you must tank vulnerable tile basses that will disintegrate if they get wet – plasterboard is the main culprit here.

    Just apply in wet areas + a bit; shower cubicles & over baths.

    WP1 = the 32/kg/sqm limit for unplastered board but if you plaster or have plaster on there already, the application of WP1 wont improve it, you will be restricted to 20 kg/sqm.

    BAL Prime APD is what you need. Topps are notoriously expensive for DIY; try for a discount or visit you local trade tile distributor who will be cheaper. I think I read somewhere that Topps give an automatic discount if you order on-line & pick up but I would still go with “looking the part” & giving the manager a hard time for a decent discount; or get it on line.

    That’s’ the kit which includes a length of tape but your better off buying a tub of WP1 & buying a roll of reinforcing tape. Again Topps prices give a false impression, look on line & as long as you can meet the minimum order you’ll save a packet; or try your local trade tile distributor.

    I’m not sure you will save much & TBO, WP1 is going to be easier for you to apply.

    Like all cement products it does age but not so dramatically as plaster; I wouldn’t advise you risk it.
     
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  7. Schmill

    Schmill

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    Richard, many thanks for your informative reply :)

    Not sure what you mean by GRP tape, but will this mesh tape do if I then coat with either plaster or adhesive:

    The only other one I could find was this, but I think this is the paper tape that you advised against using:

    Other than at Topps I am struggling to find BAL stuff, but this Unibond primer seems to cover all the bases?
    Would I be safe to assume I can use that?

    I'm presuming this is the 'non disintegrating' type of 'waterproof' as opposed to fully water proof, but again it seems to otherwise cover all requirements?

    So, presuming those items are all ok, I can get the tape, primer, and adhesive, but I am turning up a blank with the tanking paint, other than Topps again, (who's website says they do it, but give a phone number for ordering on).
    For the tanking I know I need a tub of the WP1, but when you mention the reinforcing tape, would the tape that I pictured above be usable for that, or is it something completely different that I would need, (and would probably also have to come from Topps :rolleyes: )

    Thanks for your on going advice.
     
  8. Schmill

    Schmill

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    Anyone have experience of the UniBond 'TileOn' primer pictured above?
    Seems to cover both priming and waterproofing?

    I can't find it on their website, but it is definitly in-store :confused:
     
  9. Richard C

    Richard C

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    I somehow managed to miss your post of 18th, hence the reason I did not reply :rolleyes:

    That’s the one.

    The only Unibond product I will use is their PVA & that’s for plastering. It’s not favorably recognised, use the search facility to see what many trade tillers have to say about the stuff. I use nothing but BAL; expensive but you can get decent discounts on line or even Topps if you bully them a bit. Other good products are Mapei (which B&Q trade outlets now stock) & Webber which you should be able to get from a decent trade tile outlet or order the lot online to save on delivery.
     
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  11. Schmill

    Schmill

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    Thanks Richard, no worries about the delay. Will bite the bullet then and use BAL. When you say "and a roll of reinforcing tape" with regards to the wp1, is that the same mesh tape as pictured above, or something else?
    One other thing that occurred to me, I presume it is still worth tanking even though I will be drilling through the tiles and wall for the feeds to the over-bath-shower mixer and rail fixings etc?

    Thanks again for your valuable advice.
     
  12. Richard C

    Richard C

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    It’s all I use but I do put on a couple of overlapping layers.

    As I said, PB of any sort is not ideal but you should always tank it. It won’t help if you get a leak from behind on a recessed shower valve or pipe work but still essential IMO.
     
  13. Schmill

    Schmill

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    Ok, many thanks Richard.

    I bought myself a couple of rolls of the mesh joint tape, so just need to hunt down and get the APD and WP1 ordered :)

    I presume with the tape it a case of stick it on over any joins, and then 'slap' the WP1 over it, the mesh just giving the WP1 something to adhere to?

    The pipes hopefully won't be too much of an issue as they are not recessed or buried as such, but will pass straight through the wall into the airing cupboard behind which is where the pump will be sat.
     
  14. Schmill

    Schmill

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    Figured I might as well keep this all on the same thread :)

    When I come to doing the tanking, what sort of area would you advise I actually tank?
    There are lots of examples and diagrams on how to tank a shower enclosure, but not much for a bath and over bath shower.
    I am thinking perhaps around where the bath will meet the wall all the way around maybe 6" above and below the place where the rim of the bath will touch, and then at the 'shower' half of the bath extend the tanking up as far as the shower head, and again to about 6" below the rim of the bath?

    How does that sound?
     
  15. Richard C

    Richard C

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    It's just ordinary plasterboard you have there; with an over bath shower, I’d tank at least a foot beyond the end of the bath & beyond the outside edge the shower screen, down to the floor & a foot inside the bath panel lines; tank both walls from at least 6 inches below the bath rim full height to the ceiling.

    Don’t forget to tape the corner wall junction & use a silicone bead down there after tiling rather than grout.
     
  16. Schmill

    Schmill

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    Right, today I shall be ordering a tub of the WP1 and also a container of the APD.

    After the walls are all patched, leveled, etc. do I then apply the WP1, and then just APD the areas that I didn't put the WP1 on, or should I APD the entire room BEFORE applying the WP1?

    Also whilst I am at it is there a cement based adhesive you would recommend, and an anti-mould white grout? Just thinking I could order at the same time.
    Do they need to be BAL products, or will any do? I'm just wondering whether other cement based adhesives will adhere to the WP1 or not, (was hoping to be able to use the UniBOnd fastset pictured above as I can get that locally and not have to pay huge delivery fees on a heavy item!)

    Again, really many thanks for this, I appologise for the questions but I am very eager to learn and want to make sure I do it right. :)
     
  17. Richard C

    Richard C

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    Did the link I posted on your other thread not answer your questions :?:

    You must prime with APD before applying WP1 but no need to re-prime over the WP1. If using a cement powder adhesive (in the case of large/heavy tiles) you must prime any Gypsum based plaster/plasterboard with APD to avoid reaction with the cement in the adhesive but not if you’ve already tanked it with WP1. With tub adhesive no priming is normally necessary but follow manufacturers instructions but don’t use standard PVA even if they say to do so; in fact if that’s recommended, my advice would be to pick another (proper) adhesive brand. APD can be used to prime all surfaces if conditions are dusty.

    Always best to use products from the same manufacturer. Avoid budget DIY products like you would the plague.

    For your size of tiles, I would use this;
    http://www.bal-adhesives.co.uk/products/rapidset-flexible
    & this
    http://www.bal-adhesives.co.uk/products/microflex
     
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