Question?
I have a vapor barrier under the concrete slab so why do I need a Moisture Vapor Emission and Alkalinity Control System?

Answer:
Under slab polyethylene/plastic sheeting are designed to prevent physical water from contacting the underside of concrete. These liners must be lapped, taped, with all plumbing and electrical piping sealed. They can be ripped and punctured by normal construction traffic and become ineffective. These vapor retarders do not have the ability to stop moisture vapor transmission. The plastic type liners can only retard the under slab physical water intrusion. The vapor retarders will also contain bleed water that in time can migrate through the concrete and reach the surface.


Question?
I have a low water to cement ratio, why would I need a moisture vapor control system?

Answer:
Many times the water/cement ratio is compromised as excessive water is induced during concrete placement in an effort to help in finishing. This extra water of convenience, once it evaporates will leave microscopic voids in the concrete substrate.


Question?
I had never had a moisture related problem, why should I worry about it now?

Answer:
In some cases owners, architects or even engineers were never notified that a floor had failed or is failing. In some causes the builder would use a retrofit type moisture vapor control system just to keep the job on schedule.


Question?
I use water reducing add mixtures, why should I be concerned about excess moisture?

Answer:
Designing a stringent concrete mix is a great beginning but does not allow for jobsite weather conditions such as high humidity or a very dry wind. These types of elements can change the concrete dramatically.


Question?
I live in dry desert type climate, why do I need to think about excess moisture and moisture vapor?

Answer:
The excess amount of the water of convenience in the concrete itself could definitely be a source of moisture vapor emission at a later date. This amount of water does not necessarily leave the slabs even up to a year later.


Question?
I do not like to spend the money up front so why can’t I wait until the moisture tests are performed later so at that point I may decide whether or not I need a MVE control system?

Answer:
When working in a new construction environment it is very difficult to get an adequate reading on a calcium chloride test for ASTM 1869. These moisture vapor emission rate only reflects the condition of the concrete floor at the time of the test. When using retro-fit type system they are very expensive. They also cause down time on your project.


Question?
Can you have floor failures on above grade concrete? If so WHY?

Answer:
Lightweight concrete is used on above grade facilities and is pumped into galvanized steel pans and does not allow the bleed water to completely escape from the concrete prior to the flooring material being installed. When the room is acclimated by temperatures and humidity controlled by the HVAC system, excess moisture will try to escape through the slab thus attacking the floor covering. Above grade concrete design mixes require excess water of convenience to pump the material up into the forms. The aggregates within the same mix are very porous (lightweight aggregate) and can retain water for long periods of time.


Question?
Does moisture vapor emissions by them self break down floor covering adhesives?

Answer:
Within concrete itself the pH is 12 to 13. As moisture vapor emission travels thru the concrete substrate it carries the alkalinity to the surface thus destroying the adhesives and floor coverings.


Question?
What is Sick Building Syndrome (SBS)?

Answer:
Sick Building Syndrome is a set of health problems occurring to the occupants of a particular building which seem to be related to the time the occupants have spent in that building and cannot be accounted for from any other cause. While fumes from paint and plastics as well as poor ventilation can be a cause, the more serious symptoms may come from the toxic spores from mold or fungal blooms. The main source of fungus and mold is from water that has penetrated the building's concrete walls, floors or roofs and has become stagnant in the presence of nutrients that fungus can use. While there are a wide variety of these fungi and their toxic effects, fortunately the points of entry for moisture are more limited and can be dealt with directly.