Replies

1. 
   JTC1 | Oct 18, 2007 05:53pm | #1

   Wood strip - remove after initial set? Sort of like the key in the top of a footing.

   Just a thought, not a concrete expert.

   Jim

   Never underestimate the value of a sharp pencil or good light.

2. 
   FastEddie | Oct 18, 2007 07:50pm | #2

   Strips of rigid foam 1/2" thk x 2-1/4" wide, mash them down into the wet concrete and melt them out a couple of days later.  propane torch, kerosene, whatever.

   "Put your creed in your deed."   Emerson

   "When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it."  T. Roosevelt

3. 
   xxPaulCPxx | Oct 18, 2007 10:41pm | #3

   Cut a board the thinkness of your inset, then wrap it in wax paper and staple it to the board.  You might want to use plywood to keep it straight.

   Rebuilding my home in Cypress, CA

   Also a CRX fanatic!

   If your hair looks funny, it's because God likes to scratch his nuts.  You nut, you.

4. 
   MikeHennessy | Oct 19, 2007 03:23pm | #4

   FastEddie says "use foam". I agree. Cut it thick enough to allow room for the thinset, and wide enough to allow for grout around the tile edges.

   I just used some foam to create a "cutout" in a concrete pad. Worked like a charm, and was easily removed after the crete cured -- an attribute wood does NOT have -- and it did a good job of leaving a nice, square recess. No need to melt, etc., since it was so easy to just pull out.

   Mike Hennessy
   Pittsburgh, PA

1. 
   FastEddie | Oct 19, 2007 05:24pm | #5

   I was remembering when I was on a power plant foundation project in the late 70's and we used styrofoam to create keyways between pours.  It came out real easy when it was sprayed with gasoline.  Or maybe it was acetone."Put your creed in your deed."   Emerson

   "When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it."  T. Roosevelt

2. 
   togo | Oct 19, 2007 07:00pm | #6

   This sounds interesting.  Is there a problem keeping the foam down and also finishing the concrete around the foam? Thanks for your input.

1. 
   FastEddie | Oct 19, 2007 08:03pm | #9

   There should be enough friction to keep the foam in place.  It's only 1/2" thick.  Be sure to make the foam a tad bit thicker and wider than the tile insert.  Lay a scrap 2x4 on top if it starts to rise.  Even better, use  3/4" thick foam to leave some tolerance in case it does rise a little.  Better to have the groove 1/8" too deep than 1/8" too shallow.

   I think we tied the foam to the rebar with tie wires.  Remember, this was for a foundation for a power plant.  The keyways were at least 2x4 and the pours were in the range of 100+ yards ... lots of room for rough measuremsnts.  "Put your creed in your deed."   Emerson

   "When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it."  T. Roosevelt

3. 
   togo | Oct 19, 2007 07:02pm | #7

   Mike, Thanks for your input.  What keeps the foam from rising up in the concrete?

1. 
   MikeHennessy | Oct 19, 2007 07:15pm | #8

   Same thing that keeps a wood form from floating.  ;-)

   The mix I used was not soupy enough to cause the foam to float. I placed the foam on the crete when the bottom was at the correct height, and placed the final layer of concrete around it. If you're worried about it floating, weight it down with some bricks or similar. I didn't need to.

   BTW, the gasoline or acetone sounds like a lot of fun <G>,  but it's really no big deal to just pull the foam out. It deforms enough that it comes out quite easily.

   Mike HennessyPittsburgh, PA