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10 Common Mistakes People Make While Working on their Historic Building.
        1. Repointing Bricks with Modern Mortar
                Masonry is one of the most durable historic building materials, however it is also very susceptible to damage as a result of improper maintenance or repair. Mortar is used to bond together masonry units. The interaction between mortar and brick or stone is complex and often misunderstood.  Historic mortar (lime based) was generally soft and readily allowed water or vapor to pass. Modern mortar (Portland cement) is very hard and slow to transmit water or vapor.
             Portland cement works well with modern brick or stone, but causes problems if used with older, hand-packed brick (which were fired at low temperatures and are fairly soft).
              Repointing historic masonry with Portland cement mortar can create a bond that is stronger than the historic material, resulting in a differing coefficient in expansion and porosity, causing damage. This pairing can cause rapid deterioration and failure in hundreds of years old masonry.
             When in doubt, use soft mortar.  

About Danielle Keperling

Danielle Groshong-Keperling has worked full-time in the restoration industry since 2001, but her education in the traditional trades, construction industry, and historical preservation was built from an early age through her Father's work in the traditional trades and her Mother's love of historic architecture. Now, with Jonathan (an artisan craftsman in his own right), her partner in business and life, they work together to help historic building owners restore and preserve their piece of our built history.