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Light gypsum pour??

Bob Truelson
Bob Truelson Member Posts: 2
in THE MAIN WALL
Thanks guys. I can understand the compromises on structural integrity better now. What I had planned to minimize this somewhat was just to drop between the joists along an eight foot strip down the middle of the kitchen. There would be not gypcrete/piping below the cabinets, and there would be about 3 feet of plywood still on top of the joists around the perimeter. The joists are 10" with 16" on centre. The pour would be to a point even with the sides of the exposed plywood, to make things equal for tiling. Still no good?
The main reason I want this is to maximize what I can get out of hydronic. I live in the Yukon (Canada) where we can get down to -45 degrees for short stretches anyway. Another source I was reading said that pex under plywood may not be good enough for the real cold.

Comments

  • Bob Truelson
    Bob Truelson Member Posts: 2
    Light gypsum pour?

    So I'm trying to read up on starting my first hot water heating project and have decided the best option for the kitchen is to drop the plywood between the joists, lay in piping and pour on top to keep the floor level with the rest of the house (which will be mostly baseboard hot water). The guide said to use a 'light gypsum pour' to keep weight down. What kind of a mix is that??
  • Unknown
    Unknown
    Bob,

    Check with a cement finisher, up here they call it "gypcrete", kind of a light concrete slurry that they pump-in through a hose. BTW- There is a minimum thickness it can be "poured", so if your dropping the sub-floor "between" the joists,(which I would frown-on), get a cement finisher, and carpenter`s professional opinion beforehand!

    Dave
  • scott w.
    scott w. Member Posts: 209
    not between the joist

    Bob,

    I would not lower the plywood below the joists to do a gypcrete pour. The plywood on TOP of the joists help to keep the floor solid and not bounce. If you do a gypcrete pour between the joist and put tile on the floor you cold have a very nice cracked floor if/when the joist should flex.

    Now if you are going for the antique aged look........I did a two inch pour on top of 3/4 plywood on eighty year old fourteen foot joists with some joist additions for reinforcment on 12 inch centers and I had some cracks in the gyp after 3 months.
  • Weezbo
    Weezbo Member Posts: 6,232
    Plywood offers another advantage, known as \"Rack Resistance\"

    and if you dont wan the ol lady kicking you out the rack then you best not bring the house down around her ears...

    because unlike not having the map...this subject would Never Leave her current point of conversation...*~/:) especially if some professional carpenter mentioned that you cut the structural integrity out of the house by destroying its rack resistance :)

    Trust Me, on this one...
  • Wayco Wayne_2
    Wayco Wayne_2 Member Posts: 2,479
    If you can get

    under the floor, Joist Trak plates have a real good capacity rating. Do not confuse these with the thin flashing plates that used to be offered. I use the Uponer Joist trak plates that are thick extruded aluminum and have very good capacity with them. Gypcrete is best used when you have cleared the room completely and have no strucural issues with the extra weight. WW

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