Tiling help needed!!

[scooter]

Gday all, hoping for some advice with a hearth I have to tile.

We have a 60's W/board house with an open fireplace in the lounge into which we have put a Coonara. The original hearth only extended out about 250mm, one row of thick mission brown tiles.

I have removed the old tiles and their mortar bed, which leaves the solid concrete that was underneath the mortar about 19mm below the surface of the T&G hardwood floorboards (level with the joist).

I want to lay 3 rows of 250mm floor tiles. Plan to lay them on AC sheet, which in turn will be laid over the floorboards and the old hearth which will need to be built up level with the boards.

Questions are:
-Do I use a levelling compound to build it up level with the boards, or a sand/cement mix, or...???
-Suggested using Bondcrete on old (rough) concrete surface to help the levelling layer (LL) stick to it???
-Do I use expansion joint foam or something between the LL & surrounding boards???
-How long will the LL take to cure before the AC can be stuck down to it??

-Tile adhesive? - Resaflex, or "Super TTB" (I think) has been suggested - opinion & why???

Receiving conflicting advice about whether we need to cut AC where it bridges the LL and the boards (as a "control joint"), our house is on stumps and does move (& crack walls) a bit, hence choice of 250mm tiles (so a grout joint will be above the join). We obviously don't want cracked tiles down the track, should we anticipate the movement and cut AC along the join; or is 6mm strong enough to resist any forces caused by the movement??

Any and all advice welcomed.

Thanks in anticipation...........cheers..........Sean

[wombat47]

Similar situation - probably did it incorrectly. Mixed sand and cement, shovelled into hearth "hole", more or less levelled and then put a piece of compressed cement sheet on top. Tamped that down so it was level and cleaned up a bit of excess cement mix which oozed out here and there. It's been down about 7 years and no problems yet.

A friend has a hearth of tile topped compressed cement sheet, edged with quarter round molding, which is totally free standing (or lying). It just sits over the old broken hearth. It weighs a ton so doesn't move.

[MarkV]

As wombat47 said just use a mix to level it all out and screw the sheet down to the floorboards on that end. Bondcrete is nice but if you use a powder based( you mix it) flexible tile adhesive like q-bond or kemgrip( about $30 per 10kg bag ) you should add a bit of additive to it. The tile shop will be able to supply you this at about $10/litre which is heaps for your job and it is able to be used as a primer for cement and sheeting which should cover all your needs. IMHO the 6mm sheet is plenty stable enough to prevent any cracking with this type of glue and the only issue you will have will be with the sides where you join the tiles with the ones on the walls. I have just grouted them all in the past as silastic doesn't like the heat and whilst they will crack eventually the gaps will only be tiny and being in the fireplace you won't really see em and they tend to fill up with tiny bits of ash etc and look good. This assumes that you are using a dark grout which I personally would recommend as fireplaces are grotty buggers of things anyway. Hope this helps and good luck.

[johnc]

I've done the same as Wombat, just a mud mix and cement sheet tamped level, it might sound cheap and cheerful but any movement will be between the cement sheet and the mortar, the tiles will remain nice and sound. 19mm is a bit on the thick side so washed river sand is safer than brickies sand but it really doesn't matter.

[scooter]

Thanks for the input guys, any further info/advice from anyone welcome.

From what I've gleaned today, the plan at the moment is to nail cement sheet over the floorboards only, then fill up the "hole" with a couple of layers of a mortar mix ending up the same level as the top of the adjoining AC sheet (ie, won't require AC sheet over top of mortar). After painting on a bond coat of Bondcrete to the existing concrete bed, fill to 2/3, level out and let that cure for a day or so; then do another layer up to level with the AC sheet, finishing with a wooden float so as not to "seal" the top of the mortar as apparently a steel trowel would.

After all this goes off, use Resaflex trade or Ultraflex tile adhesive to stick down tiles, apparently this stuff is very good, will stick to AC as well as the top of the mortar, is somewhat flexible, and can handle a bit of variation in the substrate (will try do get the mortar mickey mouse but very much the novice concretor!)

Leave for a couple of days (to be confirmed) for tile adhesive to go off fully before grouting.

Bit of bondcrete in with the grout mix for most of the joints, using the flexible caulk in matching colour along the "fault line".

Seal the grout with a spirit based grout sealer.

That's the plan at the moment anyway!!........cheers.......Sean

[MarkV]

Use a sheet to cover the whole area and you will not have a fault line. Also screw it don't nail it MUUCH stronger

[wombat47]

As Markv says, cut your sheet the full size of the hearth-to-be.

My sheeting is not screwed/nailed at all. I assumed that the mud would stick to the sheet, or at least form a vacuum seal. Whatever - it hasn't moved or cracked.

I laid out the tiles on the the sheet, using spacers, before cutting and sized the finished cut piece to fit the tiles. They are 30cm square terracotta tiles. I applied one coat of sealer to them before fixing to make it easier to remove stray adhesive and grout.

My Coonara heater sits on a row of bricks. They get warm, but not hot, so there isn't a heating problem with the grout.

[scooter]

Thanks guys, quick update.

Poured the mortar today; applied seal coat of bondcrete yesterday, also a bondcoat today and same stuff in with the mortar. Levelled with wooden float as intended, came up OK.

Now to let it cure for a couple of days before tiling.........cheers........Sean

[jimc]

I have been trying to find those thick brown tiles everywhere. Did you smash them all or are some still in OK condition. I need approx 8 of them. Of my head they are approx 8x8x2cm

[scooter]

Gday Jim, sorry about the tardy reply, they are pretty secondhand (small chips etc) but you are welcome to them if you want (will take off trailer!).

PM me if still interested..............cheers..........Sean