Q. We have remodeled an old house into a church. The exterior fireplace brick and mortar were covered with a water seal and the bricks have crumbled. What other coating can prevent the crumbling?
Decima Hale, Roswell, Ga.
A. The spalling on the exterior brick is most likely due to moisture penetration. The mechanism occurring then is a dissolving of available salts in the brick or mortar.
During drying crystals form from the salts, which then act much like ice crystals, thus causing the face of the brick to crumble.
A brick fireplace properly laid with first-run brick should last for scores of years without spalling. The use of ''seconds'' is poor economy when masonry is exposed to weather.
Silicon coatings are not recommended by the Brick Institute of America since they may do more harm than good.
If the appearance of the brick is unacceptable enough so as to justify the expenditure, cover the masonry with a new brick veneer - or you can plaster over it.