Carpet floor coverings hide a multitude of sub-floor sins and so when buying new carpet you mostly don't incur extra costs due to sub-floor leveling.  However, in the world of hardwood flooring things are very different.

In our experience, roughly 6 out of 10 sub-floors will need a small to moderate amount of leveling, 3 out of 10 will need a significant amount and one will be so bad that it is cost prohibitive to fix the sub-floor and so the choice to go back to carpet is made.

Leveling adds time and money to the whole project. Ignoring the need for sub-floor leveling to save money is not a good idea because once the hardwood is installed the sub-floor cannot be corrected.

The result of installing hardwood flooring over an uneven sub-floor can be:

• Excessive movement which will lead to premature failure of the flooring product
  
• Squeaks and creaks
• Gaps and separation
• Veneer delamination (for engineered flooring)
  
• Voided manufacturers warranty

The problems that come with an uneven sub-floor become evident once the floor is installed. If you install a floating floor over an uneven surface then you will notice soft spots where the floor dips when walked on.
Note that a small amount of movement is normal and to be expected with a floating floor because the underlay beneath the hardwood is supposed to compress. The problem of movement arises when the hardwood flooring is allowed to bridge two high spots in the sub-floor, say 5' apart, leaving a low spot in between. The flooring is not designed to span high spots and cannot support weight in this way. Subsequently the floor deflects down into the low spot when walked on. If the floor deflects more than 1/8" (3mm) in 10' then the industry standard has not been met.

Cosmetic cracks in concrete slabs (as shown in this image) usually  represent high spots in the concrete. These are not unusual to see. This picture shows about a 1/8" width crack that is about 6' long. Such cracks don't pose a structural threat unless something is obviously wrong such as a difference in height between one side of the crack and the other, if there is movement in the concrete or significant width to the crack such 1/4" or more.

High spots in the concrete will need to be ground down using a grinder with a diamond tip blade.  Lots of dust is generated so a vacuum attachment should be used with this tool.

Larger areas should not be hand ground as an uneven surface may be left behind effecting the floor covering. Consult a concrete grinding specialist and use a bigger machine (as seen in this image).

It takes three separate trips to site to take an Anhydrous Calcium Chloride moisture test properly and in accordance with ASTM F1869.


1. Grind off the surface layer of concrete where the dome test is to be applied and leave exposed for 24 hours.

2. Return to site to place the plastic dome test.

3. Return to site 60 to 72 hours later to collect the results.

When the NFCA Floor Covering Reference Manual is specified on the job it becomes the responsibility of the General Contractors and/or the building owner to provide and pay for such testing through a third party testing agency.  The flooring contractor should not be responsible to provide such testing as he/she has no control over the site and so cannot protect against active tests being spoiled by other trades.

Chris Maskell
Master Floor Covering Standards Institute.

Before you can teach an old dog new tricks, you must know one thing........ More than the dog!

Although consumers today spend a lot of time shopping on line, their purchases, when it comes to flooring, are usually done at a flooring retailer?
A consumer appreciates the "touch and feel" of the flooring they will purchase, as it will reflect their lifestyle for many years to come. Developing a relationship, sharing experiences, information, and needs,exhibits confidence to a consumer, and will win them over. Knowledge should be shared, 80% of consumers depend on the guidance of a sales person to help with their purchase decision when it comes to flooring.

Scott Cooper,
Director, Stanley Cooper Timber & Stone ltd.

Something as simple as a clean washed adhesive trowel can mean the difference between a successful flooring installation and a failure! A specific notched trowel isn’t just a way to get adhesive to the substrate, it’s also a metering device to put down a specific amount of adhesive for the product that is being installed.  When those trowel notches get filled with dirt and debris you are limiting the amount of adhesive going onto the substrate, in many cases much less adhesive than is required to get the recommended bond.  Every time a significant amount of adhesive is applied it’s imperative that the trowel is washed and cleaned or a new trowel is used.  A simple bucket of water that the trowels can be put into to soak so they are clean and ready for re-use will go a long way to ensure enough adhesive is going on the substrate.  The result.... a greater chance for a successful installation and a happy customer.

Mark Plausteiner
Forbo Flooring Systems