Re: Stucco Failure

Back in the mid 1950's, when I was a teenager, I dealt with a similar problem on a house built in 1929-1930 with stucco over wall tiles manufactured locally in the Pittsburgh, PA area. The diagnosis was fairly simple, there wasn't enough cement in the mixture. The contractor who started the house was getting squeezed financially and scrimped on the expensive materials. Our worst problem was that the tile underneath the stucco needed to be "pointed" because moisture was working its way all the way through the walls and leaching the interior plaster in places. A good example of a problem area was below a small window on the stairway which was on the "downwind" side of the house. Water would condense on the glass, run down to the sil, and down the wall. You could see the outlines of the tiles on the finish plaster inside the house when it was damp.

The solution was drastic. All "loose" stucco was chipped off the tiles with a cold chisel. Then the seams between the tiles were dug out up to 1/2 the width of a tile (3" in some places). Then the tiles were "pointed" with concrete, and a layer of new concrete brought out to the thickness of the original stucco. While it was still tacky, the surface was "textured" so that it had some similarity to the original surface, but it was still clearly a different color and was easily distinguished from the original. This took me two summers on scaffolding 3-4 hours a day six days a week to complete.

When all the patching was done, my father, who was an organic chemist researched available materials and found a tintable sealer which we had applied by an Amish family business. That house is still the same color and texture to this day. As far as I know, the stucco has not been repainted, which means the coating has lasted 45 years. The sealer was not a typical latex paint. It was thicker than paint and was applied with a "whitewash brush" very carefully to insure that all the rough surface was completely covered. I wish I knew more about the formula for it. It didn't smell like oil based paint or modern latex paint. It came in heavy metal 5 gallon pails.