Replies

1. 
   QCInspector | Mar 30, 2007 11:24am | #1

   I can't give you any firsthand information but Taunton publishes 2 books by Fu-Tung Cheng called Concrete Countertops and Concrete At Home. Both are great books on the subject. There is also a DVD that Mr Cheng sells but since he won't sell to Canadians I can't comment on it.
   http://www.concreteexchange.com/index.jsp

   Here is a link that might also be of interest to you.
   http://www.concretenetwork.com/

1. 
   Soultrain | Mar 30, 2007 01:02pm | #2

   I have his book & he recomends using Quikrete 5000 (along with additives that he sells on his web site).

   According to their website, Quikrete is coming out with a countertop blend soon (not sure when it will be available).

2. 
   Danno | Mar 30, 2007 03:09pm | #3

   If you are going to cantilever the concrete, seems like you may need reinforcing steel in it--I'm not sure, but you may want to check on that. Seems like any cracks that develop could go clear through and cause the slab to shear off otherwise.

3. 
   Mongo | Mar 30, 2007 04:18pm | #4

   For a floating slab, weight is critical.

   I've used perlite/vermiculite to reduce weight. Also consder forming it with a dropped edge. The main portion of the slab can be 1-1/2" to 2" thick, drop the sides for your 3-4" thick edges.

   Lightweight mixes run about 75% the weight of a standard mix, or 18# vs 24# for a square foot of 2" thick concrete.

   I use the equivalent of about a 7-sack mix.

   You'll most likely need steel "L" brackets bolted to the framing, then set the slab on the brackets. Depends on the physical size of the slab and how it can be tied in to the fireplace surround.