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Hi, we are working on our house design and hope you guys have experience of how to put in wood floors over a concrete sub floor. Its for a second story floor of a house. We have been advised that there are two options a) cut the wood into little pieces (parque) and glue it direct to the concrete subfloor, b) run 3×2 beams horizontal to the floor boards nailed in above creating a 3 inch gap between concrete and wood to enable air to circulate and the wood not to get damp from the concrete.
We are worried that option a) the glue would simply unstick in time and the floor would potentially be uneven, and the wood would get damp and warp being in contact with the concrete sub floor. Option b has us concerned about noise and possible flexing of floor if the beams are not sufficiently spaced. Any body with experience? Do we need to lay plastic down on top of the concrete to stop moisture transfer, or should we just give this up as a dream floor and tile it all!
I have some friends that have a house just a little North of Sarchi and they have some wood floors that have “cupped” from the high humidity in that area.
They are up a little in elevation enough where they are in the clouds sometimes so this might be the entire problem.
Not sure how they are attached to the concrete, sorry.To be fully cured, concrete requires about thirty days’ time. So if you’re going to install wood over concrete, give it full time to cure and give up all its excess moisture.
That said, tile will be less expensive and less trouble. We have friends who installed tamarindo wood floors over concrete on grade late in the rainy season. In a few months, the boards had shrunk so much that the installer had to come back and fill the gaps.
Would suggest using alternative B.
Use a plastic membrane over the concrete. To avoid potential noise, place strips of cork (produced for this purpose) under each of the “beams”. Neccessary to space the “beams” no more than 60 cm apart providing the floor boards are at least 22 mm thick. Good luck.I have noticed how many north Americans tend to like wood as a house building medium. Soft woods have been plentiful in North America and a building tradition with that material developed because it was inexpensive and handy. However, I have never been fond of wood floors or wood framed houses. And I don’t understrand why they would want to import that building concept to Costa Rica where an established and succuessful masonry building tradition exists.
Wood framed houses are structurally inferior to masonry and, in my opinion inferior in aesthetics. I have seen that hurricanes and strong winds in South Florida knock the wood buildings down while leaving the brick and block houses standing. There are no hurricanes in Costa Rica, but there is moisture and there are a lot of hungry insects as well. When in Rome, or Costa Rica, build with concrete and block like the Romans did and like the Ticos do. Save the beautiful hardwoods for carvings, doors and window frames.
Edited on Feb 18, 2009 08:44
Wood floors are a bad idea over concrete… really a bad idea for a good part of Costa Rica! Go with tile… I have yet to see a wood floor that stands up here… looks great when it goes down… but give it a year or so!
I’ve been inspecting hardwood floors for many years and here in CR almost all hardwood is installed directly to the concrete slabs or floor joists.
There is no doubt that traditional hardwood strips or planks will absorb the moisture in the concrete slab and eventually expand and contract causing the floors to cup. Sanding and refinishing will not solve the problem, because as long as the hardwood is in direct contact with the concrete slab, the floors will continue to absorb moisture and cup.
If hardwood flooring is to be successfully installed on concrete, the moisture content of the concrete slab needs to 3% or lower and then follow these installation procedures.
• Apply a waterproof concrete sealer to the concrete slab.
• Place two layers of 15 lb felt paper, then 6 mil plastic vapor barrier on top of the sealer.
• Nail 5/8″ plywood into the concrete slab with 1-1/2″ concrete nails.
• Place another layer of 15 lb. felt paper on top of plywood underlayment.
• Install 1-1/2″ nails into the tongue of the (minimum ¾” thick) hardwood flooring strips or planks so it adheres tightly to the felt paper and plywood underlayment.An experienced builder will help you plan ahead to accommodate hardwood flooring as the thickness of the underlayment and moisture barriers need to be accounted for when installing the concrete slab or floor joists. If not, your hardwood floors will be approximately 1″ higher than adjacent floor coverings.
Likewise, with a second floor hardwood installation on joists, the hardwood will consistently expand and contract leaving obvious spaces between the planks that will permit dirt and noise to pass from one floor to the other. In homes where hardwood is to be installed on the second floor, it’s also advisable to follow the above installation procedures (minus the concrete sealer) over the floor joists.
You can review an inspection report of defective hardwood floors in a million dollar home in one of the most exclusive subdivisions in CR at,
http://groups.google.co.cr/group/housing–property-inspections/web/water-infiltration-inspection-report?hl=enThank you all for your great input. Chromebuilder, we suspected layers of felt paper and vapor barriers would be the answer, but I had no idea if they were available here in CR, and now we can go and evaluate the cost of those options – you comments were super helpful. Sprite, I think you misunderstood, we ARE going to build a concrete block house, just exploring options for floors. We are neither committed to one or the other, we just have two huge trunks of hardwood in an old bridge on our farm that we wish to dismantle (MINAE have given us permits and all that), so we were wondering if that would be our floor or if putting in wood floor would be too much hassle and we should the wood for doors and trim (as you suggest funnily enough), or make some cool sculptures out of it and have lots of fun.
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