"The mortar on our 1840s Victorian home is falling out and the bricks seem soft. I have heard that repointing with currently available mortar supposedly would crush the bricks as it cures..."
I am the owner of an old home built right after the Civil war. As close as we can determine the house is about 130 years old. The basement walls are sand stone and are slowly crumbling. There are stones in the walls as well. What is the best way to secure these walls. Some one said to cement the walls over the sandstone. Can you comment?
First determine if the foundation walls are performing their intended function of supporting the building above and holding water and soil out of the basement. This may require the services of a competent contractor or engineer who is used to dealing with older houses and traditional materials such as sandstone. You want advice from someone who knows how your foundation could be repaired by removing removing individual crumbling stones and replacing them with sandstone cut to fit. This may not be the method you end up using, but your advisor should seriously consider it along with more modern methods.
Then determine the cause of the deterioration. The cause is probably related to water. Find the source of the water. A gutter and downspout system may be leaking or may have been removed all together letting water from the roof pour down on the foundation. Assure that water is controlled outside the foundation with good drainage systems that might include gutters and downspouts, a ground surface grade that slopes away from the foundation, and possibly an underground drainage system.
In nearly three decades of experience working on older buildings I have noticed that costly problems are often created when traditional building systems are combined with modern ones. Simply pouring modern concrete next to your sandstone foundation creates a hybrid foundation system that may not provide a long-term solution. For example, your house is used to sitting on a foundation made up of separate blocks of sandstone that shift and move slightly all along the foundation. This movement occurs slowly over the years and decades. A big section of high-strength concrete cast up against the sandstone may concentrate that movement all in one place causing a crack to run up through the house wall where there was none before.
My rule of thumb is to never use a modern method or material on an older building unless it has stood up to the test of time. If someone recommends pouring concrete up against a sandstone foundation I would ask them to show me two or three cases where this has been done at least 30 to 50 years ago. Then I would look at those cases to see how they are holding up.
John Leeke is a preservation consultant who helps homeowners, contractors and architects understand and maintain their historic buildings. You can contact him at 26 Higgins St., Portland, Maine, 04103; or by E-mail: johnleeke@HistoricHomeWorks.com; or log onto his website at: www.HistoricHomeWorks.com
© John Leeke