Having been given the opportunity in applying elastomeric paint on a wide range of substrates, I have had the experience in dealing with both the success and failures of it. With the right elastomeric and the right substrate, in my opinion there is no other paint that can give an exterior substrate a better result. It bridges those unpleasant hairline cracks, expands and contracts to prevent future cracks from appearing, shields out moisture, resists mildew, has great wash ability, and the beauty of the angular sheen finish that will last years. However, it would only take one elastomeric failure to have second thoughts on it. Usually the failure is resulting from poor preparation, improper application, the wrong elastomeric product was applied, or the substrate not being a good fit for elastomeric at all.
To help you better understand, here is 3 characteristics qualities I want to briefly touch on, Bridging, Elasticity, and Water Vapor Permeability (prem rating).
- Bridging – is when the coating film becomes thick enough to act as a bridge over a gap or crack through its cohesion and elastic qualities. DFT (dry film thickness) range from 12-24 mills
- Elasticity – The flexibility of the paint film. elastomerics elongation ranges from 160% – 360%
- Water Vapor Permeability – (prem rating). – The ability of the coating to permit water to pass through it. Elastomerics range from 5-22 prems
There are 2 types of elastomerics, one is the standard which I call the high build, the other is known as a hybrid. It is important that you have the proper elastomeric for your substrate. If not, you could be looking at issues like thisThe above picture is a commercial building I drive by daily. They originally painted the building with a regular paint, but big cracks appeared as the building settled, they had it repainted in a high build elastomeric for cosmetic reasons, it was a face lift that went all wrong.
The heavy build was the 1st elastomeric coating on paint manufacture shelves. It was designed to be a water-proofing coating. With that it had to be thick to bridge cracks (up to1/16”), and the elongation to prevent cracks from surfacing so water could not intrude. The heavy build elastomeric has a softer shell than a regular acrylic paint and gets softer in hotter elements. With it being soft it is easier for dirt to stick to it, dirt can actually embed itself in the coating. It is important that the coating does not break or tear, the substrate has to be free of open areas like around windows, vents, pipes, etc. The structure needs to be examined for any potential area where water can intrude to determine if the heavy build is the right fit. Due to its low prem rating (2-4), if moisture penetrates it can get trapped between the substrate and the heavy-build elastomeric. The coating would then do its job, just on the wrong side. It will shield the moisture in, with the elasticity it creates those water balloon bubbles you seen in the above picture. The heavy-build has its uses on the right substrate, most residential structures are not. The heavy build is mostly used on commercial buildings. Most paint manufactures won’t even have it available, as they have recommended residential painters to use the hybrid.
As residential painters begin to use the high build, some were creating their own elastomeric paint by mixing 100% acrylic flat paint with the high build elastomeric. This would turn it to a medium build elastomeric, with a higher perm rating, less elasticity and more resistant to dirt pick up. Paint manufactures were getting concerned with painters making their own paint in the field. As a result they started formulating a new elastomeric product which is considered the hybrid elastomeric. The hybrid elastomeric is a medium build 100% acrylic with the 3 characteristics qualities of elastomeric, bridging, elasticity, with a greater water vapor permeability rate. Unlike the heavy body the new hybrid could be applied on both stucco/concrete and wood, including bridging those vertical cracks in T 111 siding with the elasticity to keep them from appearing for years. The hybrid elastomeric has a harder shell with the ability to maintain its shell in warmer clients, meaning it can also resist dirt pick up. The new hybrid elastomerics have exceeded both manufactures and applicators expectations becoming a premium coating to apply on an exterior surface.
It is best to consult with a professional paint contractor that is experienced with elastomerics in your demographic area.. The following hybrid elastomeric products I recommend on the right substrate. Vista Paint 1900 Weather Master, Sherwin Williams Loxon xp, Glidden Decra Flex 300, and Dunn Edwards Paint Endurawall