Water Vapor Barrier Coatings

Protective Coatings – Polyaspartic Polyurea Are Extremely Durable

Polyurea and polyaspartic coatings are one in the same. Different markets call them by different names. These coatings are what we call protective coatings since they offer extremely durable finishes and many other advantages to other types of flooring. The strength of polyaspartic technology comes from its aliphatic backbone combined with high crosslink density that allows it to be tough and resistant to chemicals and UV radiation. These coatings were originally used as environmental control and protection coatings for architectural and structural devices such as bridges, water tanks, rail cars, pipes, oil platforms/rigs, etc… Pretty much any metal or concrete surface exposed to salt, water and UV conditions; such conditions are known to be extremely brutal on man made objects. Along the coast salt fog spray and UV exposure can cause steel to rust, polyaspartic and other polyurethane 2k type coatings offer excellent corrosion protection specifically for these environments. In time, this technology was adapted for flooring and automotive top coats because of its superior traits featuring excellent durability, corrosion resistance, and quick application/return to service times.

This floor in Austin, Texas, was underwater for several weeks. Shouldn\’t we be concerned by moisture in, on, or underneath the coating? Moisture Vapor Transmission (MVT) phenomena can present issues in floors that are/will be coated. MVT presents as an aqueous (water) layer with pressure pushing up and out that can interfere between the floor (substrate) and coating layer. In moisture related flooring failures the weakest link in the system will fail first, which is usually the coating. In the case of the Austin Yacht Clubs\’ floor, our contractors have been properly trained and know that you should never take shortcuts on flooring preparation. In this case the substrate, concrete, was diamond grinded to a suitable finish allowing the coating to penetrate. This allows the polyaspartic to soak into the concrete and to fill gaps in the pores locking itself to the concrete. It would take a significant amount of MVT and time for this coating to delaminate.

This floor survived simply because it was installed properly. The polyaspartic polyurea coating had fully cured within a few days of the original install forming a highly crosslinked polymer resin matrix within the porous concrete. When substrate prep and primer are done correctly floor coatings can tolerate moderate amounts of MVT. Floors with moisture issues will typically manifest themselves within 4-6 weeks after installation or a moisture related problem such as flooding or an underground pipe burst.

Possible Sources of Excess Moisture in Concrete

• Standing Water
• Too much water in the concrete mix (green concrete slab)
• Moisture rising from beneath the slab / foundation.
• Poor ventilation
• Groundwater and/or poor drainage
• Leaks
• Inadequate landscaping grade
• Dew point condensation
• High relative humidity 
• Coating fresh concrete, green concrete is full of water
• Failing to install a vapor barrier

All good points to keep in mind when you hire a contractor for concrete work. Moisture can affect more than just coatings. High moisture areas can cause mold, damp and humid conditions in basements and garages. As well, knowing the concrete to water ratio and other ingredients in the admix may be important if you have technical architectural plans or designs. Too much excess water in cement can result in significantly lower concrete pore density, less dense = less strong. Lower density concrete has significantly reduced compressive strength and durability. This occurs because the water leaves air behind in its place as it evaporates from the concrete during the curing process. Keep this figure in mind, concrete with 10% extra air entrapped in the matrix can result in up to 40% less compressive strength!

Vapor Barriers and Moisture Mitigation Coatings

The solution to a moisture laden concrete slab could be a moisture mitigation coating system, they\’re also called vapor barriers. Vapor barrier coatings are useful when other means of moisture mitigation were not taken or have failed. Traditional vapor barriers or vapor retarders include plastic tarping/sheets (polyethylene plastic) laid beneath concrete to prevent water vapor from penetrating the slab from underneath. Water vapors penetrating concrete slabs can cause issues such as cold, damp, clammy feeling concrete that never goes away, delaminating coatings/sealers, discoloring acid stains, producing efflorescence on the surface, damaging aggregates, and even causing the concrete slab to crack, bend or curl and move beneath objects in the floor.

Thanks to new coating technology you don\’t have to forgo decorative concrete coatings or live with cold, damp, clammy concrete any longer. New concrete coating vapor barriers are high solids, extremely low viscosity coatings. Our new Epoxy 150 W coating is a high solids, extremely low viscosity, low VOC coating. It features specialty wetting additives and siloxane technology to ensure excellent adhesion to properly prepared concrete. Our specialty epoxy formulation was designed specifically for use in moisture laden concrete slabs. This means it can be applied to green concrete (freshly poured concrete) in addition to older concrete that happens to be moisture laden. This epoxy primer vapor barrier features excellent adhesion, reduction or elimination of gassing bubbles in concrete, and sealing water penetration. The key to its success is its extremely low viscosity and additive combination that allows it to wet into concrete, it fills empty pores densifying the concrete surface creating an ultra strong surface bond. This vapor barrier is capable of withstanding 6-12 lbs of MVT depending on solids percentage and number of coats applied. For more information on this vapor barrier please contact us.