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  • How to prepare stone wall substrate for wall tiling

    Hi,

    I've just helped build a stone building using slipform masonry. We used limestone rock with concrete made from limestone products. See pictures. I'm doing it with a group of volunteers to create a kitchen for a retreat centre. None of us are tilers and we want to tile a section of the wall, about 100m2 for the kitchen area. We are wondering whether we can patch the wall with a render of sand/cement then tile to that OR whether we should batten the wall out with 13mm recessed furring channel and put villaboard onto it for a substrate.

    Would appreciate any ideas and opinions especially how we could render it or patch it to a suitable level surface.

    Tiles are Porcelain and 450 x 450.

  • #2
    Re: How to prepare stone wall substrate for wall tiling

    Welcome pointspace.

    I can't why you wouldn't render this wall. I'd say it would be a lot easier and probably cheaper than trying to recess furring channels. Patching it so that is ends up flat may difficult. If that can't be done, I'd batch the holes as best I can with sand and cement and then put a coat over the whole wall with a bagged render product. In any case, it's very important that all traces of form release agents are removed. The easiest way to do that is with a Gernie.

    You should use a good quality C2 class tile adhesive.

    Where's the job at mate? Looks very interesting.
    Last edited by Frank; 28-04-2013, 12:36 AM.

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    • #3
      Re: How to prepare stone wall substrate for wall tiling

      Hi Pointspace

      Was a solid plaster before i became a tiler. Many years ago i had similar walls to address,put on a splash coat 1cement to 1plaster sand made like pea soup,using a broom dab onto wall covering the entire wall.Secured expanding metal onto walls(it's like chicken wire with small holes) plaster wall 4sand to 1cement to float coat ready to tile as Frank said would be cheaper.The trick is find a old school solid plaster cheers

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      • #4
        Re: How to prepare stone wall substrate for wall tiling

        That looks very interesting indeed, Pointspace.

        I agree with Frank, I think render would be a good approach for your job, the only other caution I would add to Frank's savvy consideration of possible release agents, is the smooth surface of the concrete. Render does not bond well to off-form concrete. I don't know much about stone, but it looks like a fairly impervious igneous rock.

        There are a number of PVA based products out there like Cemstik or Bondcrete, but they can have limitations such as the potential to re-emulsify with water or damp. One product I can vouch for is Westox CR25, I've used it extensively, it's main purpose is for a tanking membrane, but it's also ideal for bonding render or any other toppings to structural concrete. You need to mix 1 part with two parts cement, using an electric drill mixer, then paint onto the concrete liberally. While it's still wet (and it does start to dry quite quickly) spray a scratch coat of render wet on wet using a Tyrolean gun. Let that scratch coat go off, then you can render as usual.

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        • #5
          Re: How to prepare stone wall substrate for wall tiling

          Hi guys,

          Thankyou for your replies, it has solidified our plans to render the walls. I have done some experimentation with bondcrete and kemcrete and it is bonding strongly to the wall even at 3mm thickness. Surprisingly strong actually. I smash it with a hammer after 4 days and there are no cracks whatsoever. Very tough and resilient with those admixtures in them.

          So I am going to try this:

          1. Put 12mm thick (30mm wide) Tassie Oak rails up the wall very plumb.

          2. Prime wall with Kemcrete

          3. Render the wall with 3:1 sand/ cement with Kemcrete admixture for Mortar/Render

          I'm looking at using Liquid Flash for waterproofing and Monoflex as adhesive, all of which are compatible with Kemcrete and each other.

          I'm pretty confident we can get really straight walls with this method.

          If anyone has any other suggestions or comments about this method I'd love to hear it. I will post pictures of the finished product.

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          • #6
            Re: How to prepare stone wall substrate for wall tiling

            Sounds good Pointspace.

            Kemcrete sounds like it will work and give you a moisture resistant barrier from potential lateral or rising damp as well. I'd be interested to hear how you find the workability? Many of these additives can make render very sticky, I know CR25 can be awful to use as an additive in the render.

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            • #7
              Re: How to prepare stone wall substrate for wall tiling

              Originally posted by Stonesy View Post
              Sounds good Pointspace.

              Kemcrete sounds like it will work and give you a moisture resistant barrier from potential lateral or rising damp as well. I'd be interested to hear how you find the workability? Many of these additives can make render very sticky, I know CR25 can be awful to use as an additive in the render.
              Render was completed last Wednesday and it has come up great. Thanks to a private message from Mase I bought Tassie Oak rails and installed them. This took a long time to get it right, ie plumb and straight. I had four large windows on one wall and all the battens had to be straight across. The wall is FLAT!

              Kemcrete is okay to work with. It makes the mortar go off super hard. I primed the rocks with a Bonding slurry of 1 cement to 1 kemcrete. Of course for our job the Kemcrete is expensive as we did a lot of rendering, but we don't want the tiles to fall off the wall. I researched the render and liked the document on rendering put out by the Cement and Concrete Association of Australia (I find all their publications to be top of the line). The kemcrete did make the mix go sticky but I offset this by soaking Hydrated LIme in water overnight and used this as my mix water pretty much. The hydrated lime increases the workability of the mix and it was quite easy to handle.

              The only trick was to get the cement content right to reduce initial drying shrinkage cracks. We did get a few cracks that happened quite quickly, ie in the first few hours. We progressively reduced cement content until it stabilised.

              I used a basic 1 cement: 4 sand: 0.5 Hydrated Lime mix. Kemcrete is added to the water at a ratio of 1 Kemcrete to 3 Water. I used the tables from the cement and concrete association as a starting point for my mix.

              The benefit of Kemcrete is that it does add water proofing quality to the render unlike Bondcrete. It is heavy stuff though, smells like Acrylic Paint. It is more intense than Bondcrete as a chemical.

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              • #8
                Re: How to prepare stone wall substrate for wall tiling

                We started tiling with large format tiles 450 x 450. They are going on so easy with the flat rendered wall and they look perfect! We haven't tiled before, just watched heaps of Youtube videos and of course assistance on this forum and research, research.

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                • #9
                  Re: How to prepare stone wall substrate for wall tiling

                  Attachment Attachment Attachment Attachment Attachment

                  Just uploading some photos of what I did, I've been so busy so got a few moments to give back to the forum. I wasn't able to upload some more photos I think I may have hit my forum limit.

                  Anyway in the photos you can see Kyle putting on the tassie oak battens. You can see the pink stringline getting them all straight, and him using a spirit level to plumb them in. What we did was plumbed the two battens at either end of the wall. Then run a string line to see if the wall is bowing inwards into the room. If so you need to put a batten at the point of maximum bow and adjust one of the end battens or both to take out the curve on the wall. Only one of our walls did this. We then rendered columns using a technique of throwing patties of render on the wall. We did not trowel the render on. This worked well.

                  I highly recommend the CCAA publications for all things concrete. I was a Civil Engineer and these guys produce the best and most authoritative information on concrete. I read up on render and used their mixes as a starting point on the project.

                  Issues: The CCAA publication only recommends maximums of 15mm for render. I pushed it a bit and at times had 20-30mm render. In a few places I had to pull the render out and re do it. In one section I had 50mm thick render due to the bowing wall and had to do it in 2 coats as there was no way it was going to work that thick. I did a hammer test over the entire wall and it ended up being very solid.

                  http://www.concrete.net.au/publicati...iy_render1.pdf

                  http://www.concrete.net.au/publications/pdf/render1.pdf
                  Attached Files
                  Last edited by Pointspace; 18-06-2013, 05:04 PM.

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                  • #10
                    Re: How to prepare stone wall substrate for wall tiling

                    Nice work mat. If you're ever looking for a job in tiling......

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