Overfilled Mortars on Colonial Houses

Overfilled Mortars

• Bricks are made from kiln-cooked clay and held into place with mortar. Mortar normally consists of sand, water and cement that holds the brick in place. Overfilled mortar joints describes the situation in which the mortar is not pointed and left flush with outside edge of the brick. This is not standard operating procedures for building with bricks and might be indicative of a recent repair to a Colonial-era brick structure.

Colonial Brick and Mortar

• During most of the Colonial era, mortar was made with a mixture of sand, water and lime -- with lime being the end-product of burnt, calcified limestone. This mortar mix is much softer than the mortar that is made from Portland cement, which started to appear in the early 1800s. Bricks made during the Colonial era also tended to be much softer than ones made in the 19th and 20th centuries. This was primarily because of the type of materials used and the small-scale nature of the old kilns.

Soft Bricks and Mortar

• The softer lime mortar worked well when used in conjunction with the old style of bricks. Even today many who undertake renovations of old buildings use a lime mortar mix to repair 18th- and early-19th-century brick structures. This allows moisture to escape through the mortar. On the other hand, a modern Portland cement mortar mix applied to an old exterior brick wall or pier is a potential trouble spot, as the harder mortar will block the passage of water and force the moisture to pass through the old brick.

Overfilled Mortar Joints

• Colonial era houses with overfilled mortar joints need to be checked out immediately by a professional able to distinguish the different types of brick and mortar, for the potential of long term structural damage is possible. The use of Portland cement in combination with harder building materials like granite or field stone may not cause these kind of problems, though it's best to seek a professional's opinion to ensure there's no hidden structural damage.