October 28 - November 1, 2013
During a week of heavy rain, we painted the interior walls of a heated concrete building. On the interior of walls that had an outside exposure, the paint blistered badly a week after the rain subsided. Could the rain have caused the blistering and, if so, how?
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vikram khanna of falcon international on
November 29, 2013:
For above-grade, exposed concrete walls, a possibility to protect against moisture ingress is to use silane/siloxane-based treatments after thorough joint sealing and surface crack repairs, which may lessen the chances of rain-water penetration. Plumbing conduits and vents are other possibilities of sites for leakage, along with capillary rise possibilities, as pointed out by Michael.
tim hady of tjhady painting on
October 30, 2013:
The heat inside the building caused the moisture on the outside exposure walls to penetrate through the walls and blister the paint.
Michael Quaranta of OPERATIONS 40 on
October 29, 2013:
Very interesting situation and friendly response from Mr. Felisario. I don't agree with the rain developing the water through the concrete wall. How old is the building? What is the makeup of the concrete wall and how thick? What is the geography around the building? Is the exterior wall exposed or buried in the surrounding soil? Is there a rain gutter installed on the building and suitable draining around the building? Was there any prior coating on the interior wall? What "paint" was used and how many coats were applied? There is a superior water-based epoxy coating product on the market that would easily solve this interior wall problem.
Samuel Felisario of PT RAJAWALI HIYOTO on
October 28, 2013:
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I presumed that heating is inside the room and the coating used is either solvent-based or solvent-free, therefore impermeable to water-vapor. The heat inside induces evaporation of water coming from the outer wall, leading to blistering. Try to use more permeable systems, like water-based systems, including water-based epoxy.
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