New Mortar to Match the Original

Need to match a batch of new mortar to an existing one? We’ll show you how.

Masonry buildings require relatively little maintenance. Besides occasional cleaning, they’ll need a periodic re-establishment of the mortar joint between the individual stones or bricks; this is called pointing or repointing. Masonry walls must withstand the onslaught of wind, rain, heat, water-vapor migration, and often prolonged freezing temperatures. In a well-built wall, the brick or stone masonry units erode slowly while the mortar is the sacrificial element. When voids and crevices show up between brick or stone masonry units, it’s time to consider repointing. You might do walls sequentially to spread out the cost, since deterioration may occur at a different pace. Many articles have counseled using a mortar softer than the masonry, so that the mortar rather than the brick or stone is sacrificial. Remember the aesthetics, too. Without effort applied toward tooling and color matching, repairs will be painfully obvious.

Wrong Way:

Don’t Do a Surface Job
Effective pointing mortar should extend on average ¾” to 1″ into the joint to provide mechanical adhesion; thus, all joints to be repointed should be raked to that depth. Some masons, however, routinely use a latex modified mortar that “sticks” to old mortar. The quick method requires only minimal joint chiseling; the goal is uniform appearance, not longevity. Modified mortar has water-vapor permeability different from that of old mortar and may contribute to masonry failure.

Right Way: 

Match Color and Tooling
Unless you are repointing a relatively new house, the bag off the shelf is unlikely to match. In the late 19th century, mortars were commonly colored black, brown, red, and various shades of grey and tan. Sometimes black and white particles were included. Be sure that you or your mason is familiar with the tooling of the original joints, as tooling influences the look and even the longevity of the new mortar. Tape off a 2′ x 2′ area to test the color match and tooling skills.


Tags: mortar masonry OHJ December 2015 renovation wood

By Ray Tschoepe

Raymond Tschoepe is Director of Conservation for the Fairmont Park Historic Conservancy and and adjunct faculty member of the historic preservation program of Bucks County Community College, where he teaches a core course in building conservation. He is a contributing editor of Old House Journal, for which he has written, illustrated, and photographed numerous articles. Mr. Tschoepe lectures at conferences and workshops for the Traditional Building Conference and the Association for Preserving Technology. Mr. Tschoepe graduated from the School of Fine Arts master’s program in Historic Preservation. He then worked for nearly 10 years as an independent restoration contractor. Among many preservation projects, Ray worked toward the restoration of elements of Bellaire manor, Letitia Street House, Malta Boat Club and the entry doors and panels of Founder’s Hall at Girard College.

More From This Category

Product Recommendations

Here are some supplies and products we find essential. We may receive a commission from sales referred by our links; however, we have carefully selected these products for their usefulness and quality.

Product of the Week


© Copyright 2021 Home Group, a division of Active Interest Media. All Rights Reserved.
P.O. Box 20730 Boulder, CO 80308