Portland or Lime Mortar for Repointing Lancaster Brick Homes? If your home was built about one hundred years ago, it most likely has softer clay bricks that have been laid using Natural Lime Mortar. The lime mortar is softer than present day Portland mortar and will eventually wash out if water is allowed to compromise the structure. If the old lime mortar has been washed out from the mortar joints in your brick wall or chimney NEVER repoint using Portland cement.
The City of Lancaster Pa is full of very old masonry structures that may need some masonry repairs. If the repairs are made using hard Portland cement on old soft bricks, the hard Portland will act as a chisel to the face of the brick causing a spalling effect on the face of the brick. Spalling means that the outward 1/4" face of the brick breaks away from the rest of that brick. It is unsightly and destructive to the building.
Portland repointing of bricks in the cold wintery weather of Lancaster Pa will trap any moisture in the brick due to the fact that Portland is waterproof but the bricks aren't. Therefore during a freeze cycle, the moisture that has been trapped in the brick freezes, expands and acts as a hard chisel to the soft brick face.
Natural Lime Mortar allows the moisture to escape from the mortar joint and also is malleable so if the brick expands due to freezing moisture, it doesn't act as a chisel on the old soft brick face.
Brookline Builders a Lancaster Pa historic restorations contractor specializing in all types of historic restorations including masonry, slate, clay tile and all other historic restorations.