Q & A

Ask an Old House Pro: Repairing Brick Walls

Partner Post: Maine Preservation

In a new monthly column, Christopher W. Closs, an expert with Maine Preservation, answers your questions about maintaining antique and vintage homes.

Q. I live in a brick house built around 1900 and I’ve noticed that some of the mortar between bricks is cracked or missing. Several workers have told me I should have the house “repointed.” Sounds odd. What is repointing — and what should I know before I go down that road?

– J. Russell, Fryeburg, ME

A. I agree with this observation. When the mortar between bricks erodes substantially or fails entirely, water can penetrate the walls of your house and cause alarming — and expensive — damage. Repointing involves removing some of the old mortar and replacing it with new mortar that matches the original.

Start by having your mortar tested to determine its composition and strength. A laboratory specializing in materials testing can provide this service. Most pre-1900 brick buildings have lime-based mortar and bricks that are softer than the Portland cement mortar and bricks used in later homes. The all-too-common error of using hard mortar with soft bricks will cause the latter to break down over time. If your house has lime-based mortar, your mason should use oscillating cutting tools, which are far less damaging to old bricks than circular saws. Maine Preservation can furnish the names of relevant laboratories and appropriately skilled masons. You can also reach out to a preservation consultant in your area; just be certain s/he has experience with historic masonry.

From Left: Deeply eroded brick joints shown in their neglected state and with the deteriorated mortar removed

Once you’ve settled on an expert, be prepared for a job that is noisy and dusty. After the workers have cleared away the damaged mortar, they’ll likely use a combination of compressed air and water from a garden hose to blow away grit and dust. Then they’ll apply new mortar and let it set before shaping and texturizing the surface using tools and brushes. This is where the real art of repointing comes into play. Skilled masons make sure that the new joints match the size of the old, and have the same color, texture, and finish. This sculptural approach, coupled with a seamless marrying of materials, will lend curb appeal and character to your old house.

Brick joints after repointing has been completed

Want to know more? The National Park Service publishes a series of in-depth “Preservation Briefs” on a variety of topics. You can find one on repointing here.

Cover Image: In North Yarmouth, a circa 1810 Cape Cod home is rendered in the Federal style, which was popular from 1790 to 1825.

Christopher W. Closs is field service advisor for Maine Preservation, the only nonprofit historic preservation group working to preserve and protect treasured places across the state of Maine. Closs holds a Master’s Degree in Historic Preservation from the University of Vermont and is skilled in restoration carpentry and stone masonry. You can email additional questions to Chris@mainepreservation.org and find more helpful information at mainepreservation.org.


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