You won't believe what happens next....

Your about to cover this concrete with a waterproof/vapor barrier anti-fracture membrane. You have no idea how much moisture is in this slab? Is there a vapor barrier under this concrete slab? If you seal this surface, how much moisture will be trapped? If it cannot evaporate in a normal wary through the surface, WHERE DOES THE MOISTURE GO? LIQUID WATER TAKES THE PATH OF LEAST RESISTANCE. The HVAC unit creates a vacuum, along with Moisture Vapor Transmission under the installation and that helps migrate moisture to the edges of the installed membrane! picts/mold in walls.png or real photo? Click here.

The "Perfect Couple"

1. An ASTM Approved Vapor Barrier UNDER the concrete slab. After the concrete cures, there remains 2-3 pounds of water per square foot! So at least 2,000 to 3,000 pounds of water are in great need of evaporation. How much? Most suface bonding products call for Moisture Vapor Transmission to be 3-5 lbs/24Hrs/1,000 SF or their WARRANTY IS VOID, if they even have one!
2. Moisture Factors. Is the concrete a hard trowel finish? It will take longer to dry. Did it rain? The concrete humidity will not be lower than the surrounding humidity. If it is 88% humidity, how fast do you think 3,000 pounds of water will wick up and evaporate? Is it no wonder we get this? Hey, look! No Cracks in the Tile! (At what cost?)

3. The "Perfect Working Couple". Flex-Guard Permeable Crack Isolation on the surface and ASTM Vapor Barrier
under the slab. Surface applications don't really take the place of a proper Vapor Barrier under the concrete. Your have a choice, Evaporation or Moisture Migration.

4. What is the Flex-Guard difference. Some manufacturers claim "permeability" with their product. Many are rated below 1 perm, such as .05. others are semi-perm, such as .15 or points .17, etc. Their warranties will list their product as very low performance, such as 4lbs/24hrs/1,000SF for MVT (Moisture Vapor Transmission). Many of these products were designed for TOP DOWN waterproofing, but they have very low performance with water coming up from underneath. They were used for anti-fracture membrane or crack isolation with a "benefit" of being "waterproofing".
Flex-Guard is HIGHLY PERMEABLE! ASTM 96E +30lbs/24hrs/1,000. YES! That is 30 lbs. NOT .30 lbs.