Concrete over Wood Sub-Floor - DYI

Discussion in 'Floor Preparation' started by asutherl, Jan 28, 2009.

  1. asutherl

    asutherl New Member

    So I'm new to the forums and I've been kicking around the idea of installing my own concrete floors. I'm a pretty hardcore DYI guy and rarely sub out work because I never get what I pay for (it's pretty common in Los Angeles!).

    After doing some research I think I've got the process and I wanted to validate it with the forum.

    This is levels, starting with the sub floor:

    Plywood - Clean, flat, feather patched and well screwed down to minimize movement
    Primar - To help seal the floor
    NAC EBC - This is an anti fracture membrane
    Metal Lathe - Stapled down
    Underlayment - Self leveling about 1/4 thick
    Primar - Another coat of primar depending on what the top coat manufacture calls for
    Top Coat - Self leveling 1/4 or so
    Acid statin
    Clear coat

    It would be easier to slap down some wood but I like the look and finish of concrete. Any input on my approach above?

    Andrew
     
  2. Peter Kodner

    Peter Kodner Inspector Floors Charter Member Senior Member

    Self leveling underlayments are not intended to be finished flooring.
    Also curious what your joist systems is: spacing, member type and size, spans.
    You may be better off with actual concrete if you can take the weight.
     
  3. asutherl

    asutherl New Member

    In the layers I mentioned I do would do a self leveling overlay (Miracoat or Ultratex), which would be the finished flooring. I assume the overlay can be applied to the underlayment?

    I still need to get back under the house and size the joists.

    Andrew
     
  4. stullis

    stullis Charter Member Senior Member

    I see some issues.
    Specifically with the use of EBC. Where did you get those instructions from?
    I would also recommend a double layer of plywood once you have determined the answer to Peter's questions.

    There are SLCs that can be used as finish flooring. Usually have some type of sealer applied as well.
     
  5. kwfloors

    kwfloors Fuzz on the brain Charter Member I Support TFP Senior Member

    Maybe a float out with gypcrete would save you a bunch of steps.
     
  6. Bud Cline

    Bud Cline Tile Expert Charter Member Senior Member Published

    Many self levelling cement products intended for finish flooring are available. They are acid stain-able if you so desire. In fact one company makes an entire line of such products for both indoor and outdoor finished surfaces. Clear coat wear-surfaces are also available for such applications.

    The floor structure must meet that required for natural stone flooring. Deflection not to exceed 1/720 of the span. A double layer of plywood is usually required. The first layer should be t&g glued and screwed to the floor joists, the second layer installed in opposition to the first should be exterior grade plywood screwed only to the first layer avoiding the floor joists.

    A membrane wouldn't normally be required but couldn't hurt. Perimeter gapping (1/4") for expansion should be used same as is required for tile installations. Some slight cracking should be expected from surface tension but this is said to enhance the beauty of the floor.

    These products can also be used for an etched floor as well as a stamped floor.:yesss:

    Gypcrete is not a wear surface under any circumstances and would be a poor pardner and underlayment for an SLC topping.
     
  7. stullis

    stullis Charter Member Senior Member

    Second layer of plywood is run the same direction ( perpendicular to joists) with joints offset from the bottom layer. Even better to start second layer at 1/4 point in a joist bay as well.

    Do not use a membrane under slc.
     
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