We are in the process of restoring an 1853 Italianate plantation house in upstate South Carolina. The main living level is raised about eight feet above surrounding grade on a masonry, bearing wall “basement”. (The upper two floors of the house are wood balloon frame bearing on the perimeter masonry wall as well as some internal masonry components. The bearing wall is four wythes thick and constructed of what appears to be site-made, clay-fired brick which are slightly larger than current modular bricks. In many areas the mortar is in excellent condition and appears to be composed of lime, cement and “creek sand.” There are mortar joints that we will need to clean out and tuckpoint. My concern is specifying and installing a mortar that will not, over time, create problems for the relatively soft brick the wall is constructed. I have been made aware of situations where modern mortar strengths create problems for older brick. Does any one have an idea of what or how to mix/measure an appropriate mortar to work in this situation? Thanks, Michael
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Since portland cement was not invented until the 1820s and not manufactured in the US until the 1860s, you are probably right in your contention that your mortar is a lime mortar. For Monticello, Jefferson's crew (many of whom were slaves) manufactured the lime on site by burning limestone. They also made the bricks on site. This was very typical in the South up to the Civil War.
I recommend that you use lime mortar on your house--both because it would be historically accurate and because it would not be harmful to your bricks, which you describe as soft. For information on lime and lime mortars, check out this site: http://www.lime.org/
Thank you for your input. I contacted your suggested lime site and tney have some documents that I have ordered. Is there anything on the web about masonry at Monticello that you recommend? (I will search but was wondering if you knew of anything in particular.) Thank you.
Michael, There is a great book about Monticello, written by Jack McLaughlin. It is called: Jefferson and Monticello: The Biograghy of a Builder.
Michael - The only correct way to approach this is to have a sample of the mortar analyzed by a testing firm for matching purposes. Cost around here would be about $400. The repointing (not tuckpointing, which is a specific technique, not a generic name) should be done by a professional mason with extensive experience, particularly with 19th century softer brick - it's generally not do-it-yourself work.
T. Jeffery Clarke
Edited 7/23/2002 10:38:24 PM ET by Jeff Clarke