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Concrete resurfacing over wood or plywood substrates

During renovation and remodeling of existing buildings, more and more people are looking for ways to convert their existing wood or plywood subfloors into concrete floors. The daily temperature and humidity changes cause the wood floors to move and expand under stress. The joints between boards and rough uneven surfaces become pronounced. Traditional latex-modified or gypsum based underlayments will crack along joints, break bond with lateral wood movement, and often strong enough to withstand the traffic.  
Plywood Substrate in a kitchen Plywood Substrate in a kitchen

 

Metal lath stapled over plywood substrate Metal lath stapled over plywood substrate

The installation of calcium aluminate cement based self-leveling concrete, Päram 5500 and Päram Super Primer along with expanded metal lath for reinforcement is a successful fast-track method to convert a wood subfloor into a beautiful concrete floor. We recommend applying Päram 5500 at a minimum thickness of 3/8” to withstand lateral movement and traffic stress. 

Self leveling concrete covering metal lath Self leveling concrete covering metal lath

Photo courtesy: Bill Clark, Solid Art Concrete, Chesapeake, VA

Steps:  

  1. The wood subfloor must either be solid hardwood flooring, a minimum of ¾” tongue-and-groove, APA – rated, Type 1, exterior exposure plywood, or OSB equivalent. The subfloor should be solid and fixed securely to provide a rigid base. Any boards exhibiting movement should be renailed. The surface of the wood must be clean and free of oil, grease, wax, dirt, varnish, shellac, or any contaminant that might act as a bond breaker. We recommend sanding the wood surface with 60 grit sanding screen under floor maintainer.
  2. The open joints should be filled with Sgraffino mixed with rapid-set additive.
  3. After the wood surface is thoroughly prepared, prime the surface with Päram Super Primer. The primer solution should be distributed evenly over the floor surface and then brushed into the substrate with a soft bristled push broom. Avoid pudding of primer. When applying with a pump sprayer, make sure to cover the substrate with an even coat to ensure proper penetration and follow immediately behind to work into the surface with a push broom.
  4. Allow the primer to dry to a thin, slightly tacky film (min. 2 hours, max.12 hours). Install 3.4 galvanized, expanded diamond metal lath mesh to the wood subfloor, stapling approximately 6 inches to prevent the mesh from floating. Overlap adjacent pieces of lath mesh approximately 2”.
  5. It is time now to install Päram 5500. It is mixed in 2-bag batches at one time. For each bag, add 5.75quarts of cool, potable water. Mix for at least 3 minutes with a heavy duty drill mixer (minimum 650rpm) to obtain a lump-free mix. Install at no less than 3/8” thickness over the highest point in the floor.
  6. Protect the poured Päram 5500 from excessive heat or draft conditions during the curing process. Turn off all forced ventilation and radiant heating systems. Protect for up to 24 hours after completed installation. The floor can be walked on in 3-4 hours. However, if the surface is colored using a dyes or stains or any other cementitious micro-topping (Sgraffino) or covered with epoxy or polyurethane resin coatings or simply sealed with acrylic, epoxy and polyurethane sealers, we recommend waiting for at least 24 hours. Any other type of floor covering (tiles, VCT, etc.) can be installed after 16 hours.

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2 Responses to “Concrete resurfacing over wood or plywood substrates”

  1. Paul Spurlock, on February 28th, 2010 at 1:16 pm Said:

    I supply and install self leveling underlayments and toppings, Ardex Designer Floors, concrete floor heating systems, etc.

    For more concrete flooring on wood information please visit

    http://www.signature-concrete-stain.com/concrete-flooring-over-wood.html

    For concrete floors on wood, Param 5500 would eliminate having to sell or install additional products, like a micro toppings to convert them to a wear layer.

    If they are manufactured in white, it would be a perfect fit for my customers wanting concrete floors on wood, as a white product will achieve, bolder, more vibrant color effects.

    Resurfacer

  2. Erwin Casseus, on June 12th, 2010 at 6:55 pm Said:

    I need to comment that this was a very informative blog! I have been painting concrete floors for quite some time, but I discovered a couple of things!

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