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Dew Point and Condensation problems with Flooring Installations

Submitted by steveh on Tue, 2010-11-30 16:57 in Condensation, dew point, flooring adhesive

This article is from the Construction Specifications Insitute that addresses adhesive and related problems with building floorings. The article has a lot of good suggestions for installation of floorings during building projects.

 
Dew Point and Condensation
The demand for faster construction schedules and more environmentally isolated interiors coupled with the gradual change from primarily solvent-based adhesives, asbestos, and permeable materials, has led to an increase in flooring problems... with seemingly no end in sight. The majority of these failures can be attributed to improper testing procedures, misdiagnosis, and improper repair techniques (those that give the illusion of success), but two of the most commonly misdiagnosed problems are dew point and condensation.

Explanation of dew point
Dew point is created when a surface is cool enough to allow moisture within the environment to change from its vapor (gaseous) form to liquid (water) form. Without going into a detailed explanation, there are two primary reasons for this occurrence:

1.Lower temperatures typically have lower pressures, encouraging water vapor to move from warmer (higher pressure) to cooler (lower pressure), and

2.Water becomes increasingly cohesive as it cools, causing its molecules to cling together ever tighter as temperatures drop until they solidify into ice.

Dew point creates floor problems
Dew point easily mimics a classic vapor emission problem before and during installation, and is often misdiagnosed as such. The following are ways in which dew point can become problematic (how many of these look familiar?):

Situation A
The installation environment has a moderately warm room of about 21 C to 27 C (70 F to 80 F) and a relative humidity (RH) of 65 to 70 percent or higher. The concrete is considerably cooler at 15.5 C to 18 C (60 F to 65 F). Most installers and manufacturers consider this a safe scenario. The danger here is the concrete will generally have an internal humidity of 70 to 100 percent!

This creates a dew point problem immediately upon installation because most of today's adhesives are water based. The cooler concrete absorbs the water from the adhesive until it reaches saturation. Meanwhile, the installer is under the impression the adhesive is actually starting to 'tack up' as the water evaporates (as they have been taught).

The adhesive tacks and the floor is considered properly installed. Within days (sometimes weeks), moisture problems begin to manifest themselves as the adhesive begins to ooze and/or blisters begin to appear.

Situation B
A water-based adhesive is used and the room appears to be getting clammy (more humid) during installation. The room obviously lacks sufficient airflow and dehumidification. Subsequently, the room becomes increasingly humid until the moisture within the adhesive can no longer properly evaporate (called dynamic equilibrium). The adhesive appears to tack correctly, the floor is installed and within days blisters appear and/or adhesive begins to ooze.

Situation C
The room is too cold for proper installation and fuel-driven, propane heaters (for safety reasons) are brought in. The room is then warmed to 21 C to 24 C (70 F to 75 F) and the installation begins. Unfortunately, the installer does not know propane and other carbon-based fuels are called 'hydrocarbons' for good reason. The primary 'exhaust' created when burning these fuels is carbon dioxide (CO2) and, of course, water.

Water is a primary component of these fuels and adds a substantial amount of moisture to the air as it becomes progressively warmer. To make matters worse, the warmer air now has increased pressure to push additional moisture into the cooler concrete (this explains why cold windows sweat). Within days, the floor begins to show signs of moisture failure.

Situation D
Before installation begins, the room is warmed to bring the environment into compliance for testing. Although the air temperature is within compliance, the concrete surface temperature and internal humidity may conspire to create an artificially high moisture reading during testing. Again, when room temperature is elevated in relation to the concrete surface temperature, moisture will be pushed into the surface of the concrete to create an unnaturally high vapor emission reading.
Inadvertently, the surface has now absorbed moisture from the air and the testing apparatus is incapable of determining where the moisture originated!

Situation E
The concrete has a smooth, flat, polished surface... perfect for installing an even floor. This smooth, polished concrete surface is also virtually impermeable to liquid water (in this case, water from the adhesive). It is imperative that manufacturers and installers begin to treat these surfaces accordingly. A polished concrete surface is more like ceramic than concrete when it comes to liquid absorption. It has to be treated accordingly, meaning it should be treated as an impervious surface, because for all practicality it is essentially non-permeable. Most major manufacturers of adhesives and other adhesive-dependent systems have specific instructions for non-permeable or low-permeable surface installations.

Situation F
(Primarily for fluid-applied floors, such as epoxy and urethane)
Several weeks after successful installation, blisters and/or delamination begin to occur between the primers and finish coats of the flooring system. Manufacturer and installer alike are certain they are not the cause of this problem and blame each other. Like condensation on a cold glass, a minute amount of moisture can collect between epoxy layers if the room is warm and somewhat humid. This creates a layer of compromised bond that will eventually begin to loosen as use and thermal cycles begin to force the layers to separate.

Misdiagnosed dew point problems
Dew point and condensation problems constitute upwards of 30 to 40 percent of the moisture problems investigated. Prior to a flooring specialist's involvement, the general conclusions made about the flooring failure revolve around defective products and/or installation, or a moisture problem that will be expensive to repair. In many instances, this diagnosis is made prior to the specialist's involvement by an independent consultant, laboratory, inspector, or moisture correction representative.

Specifying to combat moisture problems
With all these examples, it is easy to see how dew point problems are routinely misdiagnosed as moisture problems. Still, there are methods of specifying not currently covered by most manufacturers or professional organizations to compensate for these conditions.

The specifier should require all inspections and testing of site conditions be implemented immediately before and during installation of flooring materials requiring adhesives or fluid-applied installations in Part One-General. These products (particularly those containing higher amounts of water) are susceptible to the damages caused by dew point and condensation. Each product of this type is usually some kind of an emulsion where the introduction of additional moisture can create long-term problems, or at the very least interfere with or prevent proper curing.

Inspections conducted weeks or months earlier in the construction process are only valid at the time of testing, and may or may not represent current conditions. Inspection and testing should only be performed by qualified inspectors. Generally speaking, both the contractor and flooring subcontractor have a vested interest in the outcome of the testing results, but considering testing is beyond their scope, it is unreasonable to require either of them to do it.

The prevention of dew point is relatively easy, but will take a major change in the industry's approach to floor installation. To avoid dew point, the interior areas receiving flooring goods have to be acclimated during all phases of installation and testing.

To properly test and subsequently install a flooring product, the air temperature should be at 18 C to 24 C (65 F to 75 F), or whatever the environment is designated to be, and RH between 45 and 55 percent. The concrete temperature is of equal importance. The internal RH of concrete ranges between 65 and 70 percent for a well-cured, dry, and matured concrete, to a more normal 80 to 100 percent. If the assumption is made that newer concrete will have an interior RH of not less than 80 percent, it becomes easier to predict potential dew point and condensation problems.

Concrete has certain characteristics that give clear warning signs. For example, damp or wet concrete is slightly conductive, while dry concrete becomes slightly insulative. Understanding this subtle but important fact gives insight into how and why these problems are so pervasive.

Under the best of conditions, water-based adhesives may require several days to achieve a full cure, whereas the solvent-based adhesives would take a matter of hours. Adding water to this mix greatly complicates the installation. In a majority of cases, this type of failure does a good imitation of a classic moisture-related flooring failure, when in fact it is a conspiracy of events creating a confusing and contentious problem.

Dew point or condensation problems complicate diagnoses of failures, even with the assistance of a flooring expert. Worse yet, if the concrete has either a high pH or high alkalinity, the functionality of the adhesive can be outright eliminated. Alkalinity should not be confused with pH. A high pH can keep the adhesive in an emulsion or partial emulsion state, preventing final or complete curing, whereas high alkalinity is capable of destroying the adhesive.

A simple pH test can warn if a surface pH condition exists, but may not hint at a potential alkalinity problem. These tests are incapable of determining the alkalinity of the surface or the potential availability of alkaline components, only pH levels. An example of how pH testing cannot determine alkalinity or concentration of highly alkaline material is the following; Two cups of water are both given equal amounts of water. In one glass, two tablespoons of sodium hydroxide is added. In the other glass, 20 tablespoons of sodium hydroxide is added. After mixing thoroughly, each glass will indicate nearly identical pH values using litmus or metering devices, although one of the glasses has 10 times the alkalinity of the other.

Under no circumstances should floor-covering materials be installed on concrete surfaces less than 15.5 C (60 F) or within five degrees of the dew point, relative to ambient room temperature (unless the manufacturer agrees to in writing).

Before and during installation, the floor-covering installer is to monitor the temperature of the room and concrete surface, as well as the RH of the interior space. The RH before and during installation should be in the range of 45 to 55 percent.

Environmental controls are especially important if fuel-supplied heaters are used in cool weather construction. For example, if propane heaters are used, over 90 percent of the exhaust is hydrogen, which will combine with oxygen in the air to form water. Believe it or not, 19 L (5 gal) of burned propane fuel can introduce over 15 L (4 gal) of water into the immediate environment. If these heating approaches are employed, it is critical to specify proper air movement and dehumidification.

Improving flooring installations
After speaking with the various trades, it has become obvious the only way real change can occur is through an organization like the Construction Specifications Institute (CSI). Here, the varying agendas amongst the trades are eliminated and everyone starts from a level playing field where specifications do not play favorites.

In the specifications, provisions may be added to compensate for less than ideal conditions. The inspector can monitor the slab and room temperatures along with the RH of the room, then take the necessary steps to ensure dew point conditions are eliminated prior to, and during the installation of, flooring materials. This can be as simple as requiring the use of air movers and dehumidifiers, or more complex as site requirements dictate.

These conditions exist simply because of the nature of the problem and the chasm separating the various industries. The only way to level the playing field is to specify environmental controls within the specifications on an as-needed basis.

Although specifying and compensating for dew point and condensation may initially seem a daunting task, it will ultimately save time, money, and potential conflicts between the architect and owner. Indirectly, the long-term benefits to the flooring industry may be immeasurable.

Notes
1 This refutes the opinion of many so-called 'moisture experts' which contends moisture moves towards warmth. When moisture 'migrates' towards warmth, it is evaporating, not migrating. The water molecules are moving away from one another (this is what causes higher pressure, or expansion). When moisture moves towards a warmer, drier area (such as an open room), it is errantly referred to as diffusion, which is an intermingling of molecules, ions, etc., resulting from random thermal agitation, as in the permeation of a solid by a liquid.

2 This did not happen when adhesives were solvent-based because there was little or no water for the concrete to absorb.

3 Specifically, the hydrogen from the exhaust quickly combines with oxygen in the air to form water.

4 Called "The Industry Position on Moisture," the scope of the testing and requirements can be obtained through the World Floor Covering Association (www.wfca.org).
Table 1- Dew Point Temperature

 Additional Information

Authors
Robert C. Higgins is the vice president and chemist for SINAK Corp. and has been involved with concrete waterproofing since 1976. He has authored and/or contributed to documents drafted by the International Concrete Repair Institute (ICRI), NACE International, The Society for Protective Coatings (SSPC), World Floor Covering Association (WFCA), and ASTM International. Higgins has also acted as an expert witness in construction disputes.

MasterFormat No.
03500-Cementitious Decks
and Underlayments
09600-Flooring

UniFormat No.
C3020-Floor Finishes

Key Words
Divisions 3, 9
Adhesives
Concrete
Condensation
Dew point
Flooring

Abstract
The demand for faster construction schedules and more environmentally isolated interiors coupled with the gradual change from primarily solvent-based adhesives, asbestos, and permeable materials, has led to an increase in flooring problems... with seemingly no end in
sight. The majority of these failures can be attributed
to improper testing procedures, misdiagnosis, and improper repair techniques, but two of the commonly misdiagnosed problems are dew point and condensation.