I have an old historic building that needs some joints repointed. What mortar should I use?
A. Your old historic building needs a different mortar type than the mortar types used in modern masonry construction. Most historic buildings were constructed with bricks and mortar that are much softer and more permeable than modern bricks and mortar. The use of modern mortar to repoint soft masonry can result in long-term problems such as spalling and cracking of bricks, as well as moisture transmission problems. Prior to the introduction of Portland cement to the masonry industry in the early 1900s, all masonry was constructed with lime mortar. The lime used was not the same as the hydrated lime used in modern masonry, so historic mortars cannot be replicated by simply leaving out the Portland cement from your mortar recipe. There are several options for replicating the properties of old mortar, including mortar formulations with small amounts of Portland cement, and the use of small-batch craft limes available from Europe and some manufacturers in the United States.
A. Your old historic building needs a different mortar type than the mortar types used in modern masonry construction. Most historic buildings were constructed with bricks and mortar that are much softer and more permeable than modern bricks and mortar. The use of modern mortar to repoint soft masonry can result in long-term problems such as spalling and cracking of bricks, as well as moisture transmission problems. Prior to the introduction of Portland cement to the masonry industry in the early 1900s, all masonry was constructed with lime mortar. The lime used was not the same as the hydrated lime used in modern masonry, so historic mortars cannot be replicated by simply leaving out the Portland cement from your mortar recipe. There are several options for replicating the properties of old mortar, including mortar formulations with small amounts of Portland cement, and the use of small-batch craft limes available from Europe and some manufacturers in the United States. It is also imp
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