January 2003 - Laserfiche WebLink

Home Browse Search

U.S. HERITAGE WORKSHOP The two-day seminar was held in Chicago on November 13 & 14. Its purpose was to acquaint the participants with lime putty and it's use in preserving historic brick and stonework commonly found in neighborhoods typically built between the 1870s to the early 1930s. The use of improper materials can cause further detritions, making a bad situation worse. The workshop provided valuable information and proven field techniques to historic preservation specialists, masons, building owners, architects, consultants and engineers who are involved in maintaining historic masonry buildings. We were able to have hands-on experience in the preparation and application of historic lime mortars. We worked with cutout and wall preparation, removing hard mortar. We learned joint finishing techniques that could recreate a 100 -year-old look and to create and match ribbon and bead joint effects that are found on may historic buildings. I had a working knowledge of mortar repair, but no experience with lime putty. I have helped one contractor with recognizing existing problems with a rubble wall foundation and will assist him and the mason he will hire to do the repair. The workshop participants were told that perhaps 80 percent of all masons have no experience using historic materials. The following was used in a neighborhood newsletter. Masonry — brick, stone, terra cotta and concrete block is found on nearly every historic building. While we have few all brick houses in our neighborhood, all most all houses have masonry foundations or chimneys. Although generally considered "permanent," masonry is subject to deterioration, especially at the mortar joints. Repointing, also known somewhat inaccurately as tuck -pointing is the process of removing deteriorated mortar from the joints and replacing it with new mortar. Properly done, repointing restores the visual and physical integrity of the masonry. Improperly done, repointing not only detracts for the appearance of the building, but also may cause physical damage to the brick or stone. When dealing with any structure constructed prior to 1873 you should know that only lime and sand were used for any masonry structures. That was the year that Portland cement was first manufactured in the US. Between that year and about 1930, masons used a wide variety of lime, Portland cement and sand combinations for mortaring brick and stone buildings. Up until that time cement was considered primarily as an additive or a minor ingredient to help accelerate mortar set time. We should be very careful when re -painting or filling in either brick or stone of historic structures not to use current cement or mortar products. Because of its hardness, water cannot weep through the joints and will cause, over time, the brick or stone to fail. If you are considering repainting, please call the Historic Preservation Commission for additional information. Wayne Doolittle Inspector, South Bend HPC