Moisture Control in Masonry Buildings

Masonry requires attention and long-term care to maintain its structural integrity and visual appeal. The harsh weather that stone and brick walls are designed to keep out can destroy them if moisture isn’t properly channeled. Moisture control in masonry buildings is a critical concern, particularly in many pre-war buildings and even older structures that have withstood decades of Chicago winters.

Two major issues that commercial masonry contractors face when repairing and restoring brick or stone walls are the “washing out” of mortar joints and “thermal jacking” of walls. The long-term effects of water infiltration are at the heart of both of these problems.

How “Washing Out” and “Thermal Jacking” Occur

“Washing out” refers to the deterioration of the lime used in mortar joints. Mortar joints can “wash out” due to water infiltration. Professional masons often use tuckpointing with similar lime mortar to repair or replace the damaged mortar in washed-out joints.

“Thermal jacking,” on the other hand, is a more severe problem. Whenever moisture seeps into a wall, it collects in the wall’s core and joints. Water is highly responsive to the weather. When it freezes and expands, water can move stones and bricks, causing a wall to bulge outward. Bulging walls will eventually collapse if they are not promptly restored.

While tuckpointing commercial masonry can be costly, rebuilding invariably costs more. Construction is also far more problematic for contractors and owners than tuckpointing, especially if a structure must be occupied while the work is completed.

Mortar and Moisture Control

Air vents and weep holes are masonry walls’ first line of defense against water infiltration. These open spaces in the mortar between bricks have not “washed out,” rather they are planned holes placed at regular intervals in the wall. They allow water and moisture to drain away from the rain screen drainage system inside of a wall, which is designed to protect the core from water exposure. Air vents let air and moisture escape through the upper face of the walls. Weep holes allow for drainage at the lowest points of the wall and must be located along the bed joint.

Both “washing out” and “thermal jacking” can be abated or even avoided by regularly checking for signs of water infiltration in the mortar joints. Other potential problem spots to monitor for moisture control include roofs, chimneys, flashings, gutters, windows, and doors.

Since 1938, Soumar Masonry Restoration, Inc. has helped commercial clients across Chicagoland with a variety of masonry services, including repairs, historical restorations, and construction. Call us at (630) 216-4422 or request a free estimate online.