wood flooring_installation_preparation

          Installation Preparation

We remove and dispose of carpet, tile, marble, linoleum and wood flooring. The cost to remove these materials ranges from 1-3.00 per square foot. The two materials that cause an unacceptable amount of dust is a stone floor with mortar and wood flooring. We have dust collectors connected to the jackhammers that break up the stone and also are connected to the circular saws which cut up a wood floor. We never sweep, instead we always vacuum, for our health and your home. Added precautions we take are to plastic off cabinet, chandeliers, drapery, exits and anything that you want covered.

Substrate Preparation

Substrate preparation is needed to remove any possible contaminates that would impair adhesion between the substrate and flooring. The cost to prepare a concrete or plywood subfloor is .50 per sq. ft., and lowers when over 1,500 sq. ft. On concrete, this is accomplished with the use of large 220 volt concrete grinder that removes 1/32nd of concrete, giving the epoxy an abraded and pure substrate to bond to, which is of the upmost of importance when gluing down wide plank boards. On plywood, all nail have to be driven down, then the floor is sanded. OSHA approved dust collections systems are used in both processes. The largest reason for failure with all wood floors comes from lack of attention to floor preparation. Many installers overlook floor preparation and too many times it comes back to haunt everyone involved, every time.

Sika Corporation is our nation's leader in concrete technology. The following is their explanation of correct concrete preparation:

All concrete surfaces must have an open textured surface to allow Primer MB (epoxy) to penetrate the surface and function properly as a moisture barrier or surface consolidator. Substrates must be structurally sound and solid, surface dry, and thoroughly clean and free of laitance, oil, wax grease, paint, latex compounds, curing and sealing compounds, and any contaminant that could act as a bond breaker. Concrete, cement based, gypsum based sub-floors can be mechanically prepared to achieve an open textured surface – blast cleaning or grinding with a diamond cup wheel is appropriate. Acid etching and sanding is not acceptable. Thoroughly clean the floor with an industrial vacuum prior to installation of the Sika Primer MB.

Ardex is another leader in cement production, and the following are their statements concerning concrete preparation:

85 percent of all flooring installation failures are due to some aspect of subfloor preparation. The substrate must be smooth, clean, dry and free of all surface treatments and contaminants; curing 7 sealing compounds, parting or release agents and chemical hardeners (result in non-porous surface). Other contaminants include dry wall mud, paint overspray, oil & grease. Mechanical cleaning of concrete is needed any time adhesion for a covering is necessary, and is attained with a shot blaster, scarifier or grinder. The use of sanding equipment is not sufficient to remove curing and sealing compounds from the surface of concrete and do not use chemicals such as adhesive removers or acid to prepare the concrete! The use of solvents will result in failure. Mechanically clean the concrete! All dormant cracks larger than hairline (1/32) must be filled.

The American Society for Testing and Materials created a report (ASTMF 710) – Standard practice for preparing concrete floors to receive resilient flooring, of which wood flooring is, and states the following:

Concrete must be dry, clean, smooth, and structurally sound, free of dust, solvent, paint, wax, oil, grease, residual adhesive, adhesive removers; curing sealing hardening, or parting compounds; alkaline salts, excessive carbonation or laitance, mold, mildew, and other foreign materials that might prevent adhesive bond. Relative humidity 75% or less, max. alkalinity of 10 ph, don't use adhesive removers, flatness requirements 1/8 " over 10", a minimum of 60 to 90 days drying time for slab, moisture retarders recommended under all on-grade and below-grade concrete floors. In summary, correct floor preparation is vital for the life of your floor and few do this correctly, because they haven't the equipment or are ignorant of the necessary processes needed. Most installers use a four inch floor scraper to remove surface contaminants and others will sand the concrete with a buffer and 12 grit paper.

Both are inadequate and will only give the appearance of a contaminant free subfloor as the previous data supports.

Substrate Correction

Typically the subfloor is out of tolerance in relation to how flat it should be. When a cement contractor pours your slab, it is common for a contract to require that he pour within a 1/8 inch variance over 10 feet. When is this done or enforced? one may ask, almost never. So the responsibility fall in the hands of the flooring contractor, unless a concrete repair contractor is hired to correct the concrete to the standards set by the National Wood Flooring Association, which states that the flatness tolerance should not exceed 3/16" over a span of 10'. The high spots have to be ground down with OSHA approved methods of retaining silica dust, and the low spots have to be filled with a Portland, polymer based cement. It is very important that the cement is mixed with the correct amount of water and given ample time to dry and tested for moisture before applying the moisture barrier. Many flooring installers who lack the experience with cement will mix in too much water to make it easier to screed and level. The down side, being that when the concrete is covered prematurely, the concrete as it dries and cures will shrink and pull away from the flooring, not good! Few flooring contractors have the tools or the experience with concrete to do this well, and thus is often times not addressed or just done poorly. The end result of not addressing the concrete properly is that when a hard surface is placed on top of a substrate that isn't flat, it follows the substrate and because of the sheen it becomes visibly, very noticeable and you can feel it much more when walking over it than when you have carpet. When I point these areas out to homeowners they are amazed that they didn't realize them before when living on carpet. The other problem is hollow spots, where there are low spot over a short span. The wood flooring doesn't bond and is subject to surface moisture and can cup, and is just annoying as you walk over them and feel the give and hear the difference in sound.


Moisture Protection

Moisture protection is more important than you might imagine. 85% of flooring failure is due to either a poor bond between the concrete and moisture barrier, an inadequate barrier for the amount of vapor transmitting upward or hydrostatic pressure. More common than hydrostatic pressure is moisture vapor and is the result a process called enthalpic evaporation, which in layman's terms is a source of water that through certain physical forces, causes the water to evaporate and find the path of least resistance to your floor covering and cause expensive damage. The excessive water below your slab could be due to a high content of clay in your soil, over watering the vegetation within a close proximity of the exterior walls, or water draining down a hill. This doesn't have to be a problem, but most installers just don't have the right tools to prepare the concrete so the moisture barrier can adhere correctly or don't follow the manufacturer's guidelines for a correct application or use an inadequate product. The first step in this process is to test the concrete or plywood for moisture in key locations throughout substrate in which wood flooring is going to be installed, then documenting the findings and selecting the correct product for the application. I have tested all the moisture barriers on the market, because of the various unorthodox installations that I'm asked to do, and only one meets all my needs. Most installers aren't using it, instead they choose to use products that are slightly less in cost or only use products that are marketed much heavier to the mainstream flooring market. No matter what product is used, if the product isn't applied to the manufacturers specification, it may fail, thus voiding any warrantee and you're stuck with a mess. An extreme example that I like to use is an installation I did in La Jolla, CA, on a hill, I installed 7" wide, solid oak flooring in a basement, over concrete. Six months after the installation they had a flood, with standing water over 12 hours, all the woodwork near the floor cupped and buckled, but my floor stayed intact, with no damage, because the concrete was prepared correctly, I used the right products, and applied them correctly. 

If I hadn't, the owner would have been in for a huge expense, as no warrantee would cover any level of flooding. I use Sika's MB primer, as it is the only epoxy that penetrates the concrete up to five millimeters and is able to do that because of its lower viscosity. The major benefit of it penetrating the concrete is that its bond is maximized, where other products with higher viscosities don't penetrate and merely coat the cement. I have done numerous repairs where the epoxy just peeled off the concrete and was the reason for the failure. Another benefit of Sika, is that it is not solvent based, which is a major health and safety consideration. If you are living in your home during an installation, which is so often the case, you certainly don't want to be breathing in the toxic off-gasing of solvent. With solvents, there is always the risk of fire and explosions, when applying solvent based epoxies. It's a good idea to turn off pilot lights and no smoking or you may be left looking like Wile E. Coyote with a burnt umbrella. For technical information on Sika's MB Primer, please click on the following link: http://us01.webdms.sika.com/fileshow.do?documentID=331