Restoring Masonry Buildings: A Comprehensive Guide to Preservation and Safety - Part Two

Oct 8

Last month, we introduced you to the basic importance of repairing masonry buildings. In this article, we’d like to distinguish the several different types of masonry deficiencies, and how to identify them.

Types of Masonry Deficiencies:

1. Incorrect Masonry Repair: Previous inadequate repairs can worsen existing issues.

2. Spalling: Chipping or flaking of a masonry unit’s surface, often caused by freeze-thaw cycles or moisture ingress. This reduces the durability of the masonry allowing for further deterioration and the potential for water infiltration.

3. Efflorescence: Water and salts within the masonry can create a white, powdery deposit on the masonry surface which can indicate that there are water-related issues in the masonry.

4. Deteriorating Mortar Lines: Crumbling or eroded mortar joints can compromise the bond between masonry units which weakens the overall structure and can allow for water infiltration.

5. Deteriorating Grout/Mortar Lines: Deteriorating mortar joints were not repointed as they should have been with an appropriate mortar but grouted as a form of repair. This grouting has created a scenario in which there are differing hardnesses in the fabric of the wall. As a result, environmental fluctuations such as thermal and moisture conditions cause the bricks to expand and contract at different rates than the grout and mortar thereby causing further deterioration of the grout and occasional spalling of the bricks themselves.

6. Crazing: Fine cracks on the masonry surface often due to shrinkage during the curing process. They can allow for water infiltration and compromise the surface weather resistance.

7. Cracking: Cracks on the surface or within masonry units can be caused by several factors such as settling, ferrous anchors, freeze-thaw cycles and water ingress, thermal expansion and contraction, or structural stress.

8. Delamination: This is the separation of layers within masonry units which is often caused by freeze-thaw cycles, or poor construction. Delamination is concerning as it can lead to further deterioration of the masonry which will weaken its structural integrity.

9. Pitting: Small holes or depressions on the surface of masonry units resulting from aggressive weather exposure. Pitting can lead to further deterioration.

10. Coving: Gradual rounding of the edges of masonry units compromising the structural integrity and water infiltration.

11. Chipping: This is when the corners of the masonry break. This can allow for loss of the unit's structural integrity and allow for water infiltration.

12. Blistering: Formation of raised protrusions on the surface of masonry units caused by moisture trapped beneath the surface. This is often a sign of water-related issues.

13. Ferrous Anchors Corrosion: Masonry-embedded metal anchors will weaken structurally when exposed to water.

Identifying Damaged Masonry or Mortar:

1. Visual Inspection: Locating and cataloging cracks, discoloration, and areas with missing or dislodged pieces may help indicate underlying structural, water infiltration, and other issues.

2. Probing: Using a tool to gently probe the mortar joints to identify soft or deteriorated areas.

3. Sound Test: Tapping on the masonry with a hammer can reveal delaminated or hollow areas, indicating potential deficiencies.