Repair necessary for building longevity

By The Standard Staff - 06/01/2008

Larry Smith demonstrates how to repair brick on an Uptown Butte building.

Editor’s note: The following is one of a series of columns to run throughout the summer from the Citizens for Preservation and Revitalization. Topics will concern Butte’s architecture and other topics that relate to its historic buildings.

There’s no shortage of historic brick structures in Butte. And often, that brick is in need of repair.

Masonry structures are popular for their high fire resistance and low maintenance.

Over time, though, the weather, wind, and especially moisture can cause deterioration. By design, the mortar joints between bricks in a masonry wall will need attention.

The term “repointing” comes from the masonry term “point,” which means to fill or refill, finishing the joints of brick and stonework with mortar.

Most historic exterior brick walls will need partial or full repointing every 50 to 70 years. However, physical damage or moisture problems can cause mortar to fail prematurely.

The first thing to know about a brick wall in need of repair is the hardness of the brick. This dictates the proper type of mortar to be used.

Common brick is by far the most used in historic Butte buildings. A lower firing temperature makes common brick softer, less tolerant to high compressive stresses, and more permeable to water vapor. Higher quality historic brick and modern brick do not suffer as much from these issues.

Since common brick is weaker and more permeable than modern brick, it is essential that the proper mortar be used. Mortar used for modern brick is sold in pre-mixed bags and will not work effectively for common brick.

Mortar appropriate for historic common brick used in Butte is mostly composed of sand and lime, with a small quantity of Portland cement. Here is a formula: 8 parts sand, 2 parts lime, 1 part Portland cement.

Narrow “pointing” trowels and other necessary materials can be found in local stores.

Once ready to begin, the mortar joints are scraped out using your hands. Compressed air then gets rid of debris. Then simply pack in the new mortar.

With practice, building owners can do a professional job that will last a lifetime.

A brief handout is available from Butte CPR, and at http://www.buttecpr.

org/bricks.

Larry Smith is president of Citizens for Preservation and Revitalization. For details about CPR, visit http://www.buttecpr.org/.

Brick repair workshop set A hands-on workshop to introduce people to the repair and maintenance of historic brick is offered this week.

The introduction to the materials, methods, and distribution of reading materials will be held 6 to 8 p.m. Thursday, June 5, at 27 N. Excelsior. A hands-on practice follows 9 a.m. to noon Saturday, June 7, at an Uptown building. Cost is $10 for members, $30 for non-members.

It’s presented by Butte Citizens for Preservation and Revitalization. For details, contact Larry Smith at info@cpr.org or 491-8623.