All concrete surfaces continuously emit moisture vapor. This is a natural and necessary function for the health of the concrete. Too little moisture in concrete causes the natural,
continuous process of hydration to cease and the concrete weakens
and structurally dies. Too much moisture causes the bond of all
types of flooring systems to fail for various reasons.
Some slabs reach a point at which the pores or capillaries of the concrete are no longer freely passing the moisture vapor as a gas, but are completely full of liquid. This point is known as "critical saturation."
Moisture emission is measured by conducting a calcium chloride crystal test. In this test, changes in weight of moisture absorbing crystals exposed to concrete for specific lengths of time produce results that are expressed in terms of pounds. The test determines the weight
of the emitted moisture as it would occur over a 1,000-sq-ft slab surface during a 24-hour period. Proper testing methods are critical and will produce a working representation of actual amounts of moisture emission.
The calcium chloride
test is the only qualitative and quantitative test. The American Society for Testing
Materials has set standards for the test, and the World Floor
Covering Association recommends that only qualified, independent
agencies perform it.
You should always test the moisture level prior to a flooring installation.
If the moisture vapor emission level is above 3 lb, floors will develop signs of
bond failure and flooring materials may not stay down.
Flooring manufacturers do not recommend that their products be applied if the moisture emission level is above 3 lb. However, the majority of concrete slabs throughout the United States are well above 3 lb.
Some floor coverings fail because the adhesive re-emulsifies and some
fail because the trapped moisture disintegrates the concrete surface
cap to which it is bonded.
High pH (alkalinity) also plays a direct part in bond failure.
Sealflex Industries, Inc. is able to advise, assist, and help coordinate answers with floor testing facilities, construction companies and floor contracting companies concerning moisture related flooring problems.
A. HERE ARE A FEW SIGNS THAT INDICATE A MOISTURE PROBLEM IN FLOORS:
- Tile peaking at the seams
- Alkali present at the seams
- Presence of excessive adhesive in the seams
- Air pocket bubbles visible in the flooring
- Hollow sounds in the flooring - visible water coming from seams when pressed on.
- Visible rippling seen in the flooring materials
- Loose tiles
- Mildew and musty odors in carpets
- Wetness under plastic carpet pads
B. HERE ARE A FEW QUESTIONS TO ASK REGARDING THE INTERIOR OF BUILDINGS WITH MOISTURE PROBLEMS:
- How are the floors cleaned? Is power floor cleaning equipment used that may force water below the tiles?
- What floor cleaning chemicals are being used? Are these chemicals compatible with the adhesive?
- Are there plumbing leaks under the floor slab?
- Were there any trenches cut into an existing slab that may still be too green?
- What floor-fill was used, if any, to fill low spots, expansion joints, cracks, etc.?
- Was the proper amount of adhesive used? What trowel was used? Did the adhesive have proper open time?
One very important aspect to keep in mind is that air conditioning and heating inside a building will cause moisture to be pulled into and through the concrete floor.
C. THE OUTSIDE OF A BUILDING IS THE LARGEST CONTRIBUTING FACTOR TO THE
MOISTURE PROBLEMS INSIDE OF A BUILDING STRUCTURE. CHECK FOR THE FOLLOWING PROBLEMS:
- The outside bituminous water-proofing compound should have been applied below the floor slab on all perimeter walls and applied properly.
- On many buildings, extensive exterior water-proofing products may have been applied improperly.
- Was a membrane placed under the slab? Were holes punched in the membrane voiding its performance?
- Check the sprinkler system. How close to the building is it? How many minutes during the week is it on? Determine the amount of water possibly going into the concrete slab.
- Look at the plants beside the building. Are they the type that require a lot of water? How wet is the soil and how deep is the moisture? Moss on the building, for instance, can be a sign of over watering.
- Planters along side the building that are not properly water-proofed will leak a very large quantity of water into a building.
- Has the land use changed from little or no nearby buildings to high development? Water tables change.
- Nearby hillsides contribute highly to water entering a slab.
Sealflex Industries Inc. can provide you with more information about moisture.
Please Contact Us if you are interested.
