Tiling the hearth setting the tile and grouting

Tiling the hearth setting the tile and grouting

Tiling the hearth: setting the tile and grouting

After my previous tile setting attempt. which failed became a preparatory step / learning experience, I felt I had a much better understanding of the materials I was working with and how to achieve the desired spatial relationship between the tile, edging, and surrounding wood floor.

I laid out all my materials and tools so I was ready to go.

Setting the tile

I mixed the thinset much thicker this time, to a nice sticky peanut butter consistency. I applied the thinset to the floor with a 1/4 inch square notched trowel along two of the edges first and set the edging in it.  I pressed it down as far as it would go because I knew from drysetting everything over and over again thats where it needed to sit.  Normally, one lays tile starting in the middle of the field and working out to the edges, but I needed to start at the corners and work inward to make my edges line up perfectly.  From my numerous dry runs, I already knew the spacing would work with 1/4 grout lines.  In the field, I troweled notches perpendicular to the previous (hardened) notches.  By holding the trowel at a shallower or steeper angle, I made the notches shorter or taller according to the little map I had made.  (See previous post if you dont know what Im talking about.)

It was pretty smooth sailing.  I used shims to keep my edges even, and I pushed the mitered ends of the edging together until I had perfect corners.  When I had all the tiles set, I started tapping on the tiles to make sure there was enough thinset under all areas of each tile.  The very right front corner sounded hollow.  I pushed the tile away from the corner as much as I could and saw that the thinset hadnt squished over to the edges on that tile as much as Id hoped.  My first thought was to put some thinset in a ziploc bag with the corner cut off (like a pastry bag) and apply a bead of thinset around the edge and push the tile onto it.

I did that, but I wasnt satisfied with the result.  Although the hearth wont be walked on as much as if it was some other section of flooring, I worried that this particular tile being in the front corner of the hearth could see some traffic over time, and I didnt want to risk the tile getting broken due to not having enough thinset under it in the corner.  So I lifted the tile using a concrete edger (similar to  pictured, but obtained for $1 at a garage sale) to get under the edge and pull it up.  That worked well.  I scraped the thinset off the tile and the floor, rinsed the tile and let it dry while I troweled new thinset onto the floor, making sure my coverage was good all the way to the edges.  I reset the tile and was happy with the result.  You can see in the photo the piles of thinset I scraped off onto paper towels.

I had all my tiles set.  Woohoo!  I used my straight board again to make sure the tiles were all even with each other and the floor.  Then I cleaned up any excess thinset from between the tiles, cleaned the surface of the tiles and edging, and cleaned all my tools.  To keep the dogs from stepping on the tile for at least a day, I put the big piece of plywood over the hearth, raised up on some pieces of 2×4 set around the hearth.

Things I did differently (i.e. better) this time:

  • taped the dropcloth to the floor so it wouldnt slide around
  • mixed thinset thick like sticky peanut butter
  • knew that I would have a couple hours to work with the thinset and that it would easily clean off the tile and edging when I was done, so didnt panic if a tile needed to be reset or I got some thinset on surfaces
  • started with a base at the exact right height — key to success in this case

I waited almost a week to grout, not because the thinset needs that long to cure, but because I was working on weekends.  On the advice of several people, before grouting I applied a sealant to my tiles to help keep the grout from sticking to them.  This is unnecessary when working with glazed tiles, but with stone, the grout can get worked into the surface and be very hard to clean up unless it has been sealed.  We like the look of the natural stone, so I made sure to use sealant that is not an enhancer (enhancer sort of makes it look wet all the time and emphasizes variations in the stone).  I mixed up the grout according to directions, just mixing it by hand in a large yogurt container since I didnt need a lot.  I liked the ziploc bag as pastry bag method, so I dumped all of the grout into a bag and cut the corner off.

I applied a thick bead of grout to all the spaces between tiles and to the small space between the Schluter edging and the tile.  Then I pushed the grout into the cracks with my float, worked it all the way in, and scraped off the extra.  I did not grout between the edging and the wood floor nor between the tile and the brick facade of the fireplace (grouting between different materials such as tile to wood or floor to wall is a big tiling no-no as this will crack and cause problems over time, but the space between the edging and tile is meant to be grouted).  To prevent any grout from accidentally getting in the space between the wood floor and the Schluter edging, I had applied blue painters tape.  These spaces will be filled later with sanded caulk. [Edit: Two years later, I never did take the step of filling that gap with sanded caulk. It looks fine. The only time I regretted not doing it was when someone spilled a drink on the floor and I was a little bit worried about moisture in the crack. I may still do it sometime.]  After letting the grout set up for about 15 minutes, I cleaned the tile surface repeatedly with a grout sponge (which apparently has magical properties and should not be replaced with a regular sponge) and clean water which I had to change a couple of times to make sure I wasnt just smearing the grout around.

As the grout dried, I cleaned the tile again with my grout sponge, making sure to squeeze out as much water as possible.  I checked every couple of hours to see if a haze was forming.  Ive read that this haze, if present, must be cleaned off before the grout cures or it may become extremely difficult to remove, so even though I didnt see any haze, I buffed the tile again.  And here it is all done.

We think it looks great.  Its almost perfectly flush with the wood floor; you cant feel any height difference if you step on the edge.  I really couldnt be happier with the way it turned out!


p.s.  For those out there who might be planning their own hearth tiling project, I will provide a materials/tools/cost breakdown in another post along with some tips I have learned.  [Update: the full Hearth tiling project recap  is available.]

p.p.s.  Now we can finally have the installers return to make the final hookups on our Mantis fireplace insert and install our new tankless water heater!

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