reinforcing mesh in lightweight concr...

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Author Message Robin E. Snyder Senior Member Username: robin Post Number: 212 Registered: 08-2004 Posted on Sunday, October 19, 2008 - 09:55 pm:    This is my assembly - top to bottom - seamless urethane cement flooring over lightweight concrete topping slab with reinforcing mesh (to prevent cracking), over Noble waterproofing sheet membrane, over concrete slab (above grade). Question: What size of reinforcing mesh would you use? What verbiage would you use to specify the installation of the reinforcing mesh? Thanks! Anne Whitacre, FCSI CCS Senior Member Username: awhitacre Post Number: 840 Registered: 07-2002 Posted on Monday, October 20, 2008 - 12:51 pm:    how deep is the concrete topping slab? Robin E. Snyder Senior Member Username: robin Post Number: 213 Registered: 08-2004 Posted on Monday, October 20, 2008 - 01:27 pm:    3 to 4 inches Richard L Matteo, AIA, CSI, CCS Senior Member Username: rlmat Post Number: 306 Registered: 10-2003 Posted on Monday, October 20, 2008 - 02:15 pm:    Robin, What is the "urethane cement flooring" product on top of the concrete? Are you using the "NobleDeck" product for the waterproofing? My waterproofing/deck coating people tell me that it is generally NOT a good idea to put a coating on the concrete slab if there is waterproofing below as it traps the moisture in the slab. As for the size of the wire mesh - I would get that from the Structural Engineer. Lynn Javoroski CSI CCS LEEDŽ AP SCIP Affiliate Senior Member Username: lynn_javoroski Post Number: 818 Registered: 07-2002 Posted on Monday, October 20, 2008 - 02:30 pm:    As to moisture, lightweight concrete has a greater moisture dissipation problem than normal weight concrete, so trapping the moisture could lead to delamination of the "urethane cement flooring". You'll have to do some testing for the moisture content before the flooring application and perhaps use a special prime-type coat to mitigate the moisture problem. I'm told Sika has such a product and there are a few others. Robin E. Snyder Senior Member Username: robin Post Number: 214 Registered: 08-2004 Posted on Monday, October 20, 2008 - 02:43 pm:    The urethane flooring manufacturer is aware of the moisture issue and is working w/ the structural engineer to design the appropriate mix and they state that their product will allow moisture to escape. So, the question is about the reinforcing mesh. Robert W. Johnson Senior Member Username: bob_johnson Post Number: 184 Registered: 08-2004 Posted on Monday, October 20, 2008 - 02:57 pm:    Why isn't the structural engineer also determining the reinforcing in the slab? Richard L Matteo, AIA, CSI, CCS Senior Member Username: rlmat Post Number: 307 Registered: 10-2003 Posted on Monday, October 20, 2008 - 03:00 pm:    Robin, Sorry, but I've done a number of these and I have to agree with Lynn - you will have a problem with the urethane coating. If you can tell us who's product it is we might be of more help. As I mentioned, you need to talk with the structural enginer about the size of the mesh - he's designing the slab. I still think you should forget about the coating, otherwise make sure you get a warranty form the coating manufacturer in the event the coating fails. Robin E. Snyder Senior Member Username: robin Post Number: 215 Registered: 08-2004 Posted on Monday, October 20, 2008 - 03:13 pm:    its Diamondstone Diamond-Crete RT - it is a kitchen floor in a casino. Mark Gilligan SE, CSI Senior Member Username: mark_gilligan Post Number: 104 Registered: 10-2007 Posted on Tuesday, October 21, 2008 - 02:01 am:    I agree with Richard and Robert in that you should engage the structural engineer on these sort of discussions. All too often on this forumn specifiers seem to feel the need to make decisions outside of their expertise when another team member has that expertise. Why is that? Jerome J. Lazar, RA, CCS, CSI, SCIP Senior Member Username: lazarcitec Post Number: 605 Registered: 05-2003 Posted on Tuesday, October 21, 2008 - 08:39 am:    sometimes it is because no matter what you do the other team member does not step up to the plate to do their job - its always a matter of time, I've had plenty of incidences where we have asked the consultants on the project to perform, sometimes we are totally ignored or the answer is delayed, granted many times it is our fault for not giving the consultant time, but how much time do we get to begin with. I agree with Richard and Robert as well, I don't have time to wear the engineer's hat on my projects, but time does not permit a lacadaisacal attitude. This seldom happens when I know the consultant, but on many projects the consultants are new to me. And I reluctantly have to solve the problem without their help.