When installing tile, whether it’s flooring for a restaurant kitchen, a swimming pool or a patio deck, the process should include waterproofing the substrate prior to the tile installation.
Coatings fail to bond to concrete for two reasons:
- Lack of sufficient surface profile.
- Moisture in the concrete
Today, most coating manufacturers require concrete substrates to be dry (<5% moisture content) with low vapor transmission (< 3-5lbs per 1000 sq. ft./24 hours) before applying most types of membranes. This applies to both new and existing concrete substrates, although each may have its own set of moisture-related problems. For example, a 90-year-old poured-in-place partially buried concrete tank may face an entirely different set of circumstances from a newly constructed concrete slab with a steel tank mounted on it. Ultimately, the concrete needs to be dry prior to coating.
Polyurethanes are used to make products with properties ranging from soft flexible foams such as memory foam mattresses, to rigid foams used for house insulation. They can be made into soft rubber as used for skateboard wheels or into very hard enamels as used in modern automobile paints.
The range of properties can be quite wide, just by changing the chemistry a little, but there's a problem. The traditional chemistry uses materials that have an affinity for water. For applications such as fountains, pond liners, waterproofing, water and waste water tanks, roofing — where long term or constant immersion is an essential requirement — that affinity for water will lead, eventually, to the product swelling or even failing. The reason is in the chemistry, itself. Here’s why.
With so many epoxy, latex, polyurethane, polyaspartic and other type coatings in the market; selecting the appropriate coating to meet your project needs can be challenging. In deciding between a single part or two part coating it is useful to have a basic understanding of curing mechanisms, coating types, and selection protocols to narrow the choices.