Any coating that goes over brick, stone, or stucco has to allow water vapor to pass through it. That's why oil-based finishes must be avoided; they trap moisture, wreak havoc on mortar, and quickly fail. Choose one of these three options instead. Acrylic:
High-end house paints (above, over brick) do allow moisture to escape but need an alkali-resistant primer to protect them from cement's high pH. Similar to shown: Stellar 249 in C5200, about $60 per gallon; C2 Paint
An ancient coating formula of slaked quicklime and mineral pigments gives masonry a rich, old-world look. Its velvety finish wears off easily and needs to be reapplied about every five years. Products such as Pit Lime Paint (starting at about $50 per gallon; Unearthed Paints
) can be ordered online. Mineral:
Instead of resins and solvents, mineral paints, such as Quartz Guard (about $90 per gallon; LimeWorks.us
), use silicates, which chemically bond to masonry to form a completely breathable, extremely durable skin. Two coats should last 50 years.