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Masonry maintenance
Tuckpointing
The process of cutting out old mortar to a uniform depth and placing new mortar in the joint is used to repair mortar joints that have deteriorated.
Mortar joints are considered deteriorated when:
- They have eroded back more than 1/4" from the face of the unit or beyond the depth of the original joint
- Cracks are visible within the mortar
- The bond between brick and mortar is broken or the mortar is soft and/or crumbling
- Any portion of a mortar joint is missing
The deterioration of mortar is caused by any or all of the following factors:
- When excessive moisture can enter a wall and freeze repeatedly, spalling of the mortar and brick will occur due to the expansive nature of frozen water. The sources of moisture entry, beyond normal exposure include leaks in flashing, gutters, lintels, sills and sealant joints.
- Older buildings were commonly built without adequate expansion joints and cracking occurs when building movement, from thermal expansion, is not provided for. All clay products (brick) grow in long term service while concrete products shrink.
- Uneven settlement in a building's foundation may occur resulting in cracking.
- Although more predominant in very old buildings, the composition of the mortar used may be such that it is unable to be as resistant to severe weathering. For example, the use of high cement content mortars can result in loss of bond between brick and mortar.
- Erosion from water, wind and pollution.
Process
The process of tuckpointing involves these steps:
- Identification of wall area(s) in need of repair
- Removal of the defective mortar with the proper tools to prevent damage to adjacent masonry units
- Removal of dust and debris from joints to be pointed by brushing or flushing with water
- Mortar is mixed that closely matches the existing in strength, hardness, color and texture
- Dampening of the mortar joints before the mortar is pointed in
- Tightly packing the fresh mortar into the joints in thin layers (1/4" maximum)
- Tooling of the mortar to match the original profile after it has become “thumbprint” hard
- Light brushing of the joints to remove any excesses
- Application of commercial cleaners to remove any mortar stains
Once a wall area has been properly tuckpointed it is not only a wall with improved structural integrity, but one that is more resistant to moisture penetration for years to come. An added benefit of tuckpointing is that the overall appearance of the wall is enhanced with new mortar in place.
Replacement
When excess moisture within brick or concrete block freezes, the result often times is the cracking, spalling or disintegration of these units. This is due to the expansive nature of confined moisture as it freezes.
Deteriorated brick or block would be identified and replaced with new units that closely match the original in size, color and texture. Repair of conditions that expose the masonry to abnormal moisture is recommended to keep the same deterioration from occurring in the future.
Caulking
Missing or deteriorated sealant within building expansion joints and at the perimeter of masonry openings (windows, doors, etc.) is often the source of moisture entry into the wall system.
Sealant failures result from:
- Improper joint design (width of joint)
- Incorrect type of sealant used, i.e., silicone, urethane, acrylic
- Lack of proper preparation (cleaning and priming) prior to sealant installation
- Incorrect placement of backing rod (the material behind the sealant used to control its depth or width-to-depth ratio)
- Incorrect placement of backing rod (the material behind the sealant used to control its depth or width-to-depth ratio)
- Age and exposure to ultra-violet light from the sun and climatic extremes
These joints should be professionally inspected and if the sealant has torn or lost elasticity, should be cut out completely and new sealant properly installed.
Through-wall flashing
Masonry walls effectively resist moisture when properly designed and constructed. Excess moisture may develop within the wall system if an effective means of relieving the absorbed moisture is not used. The result of this can lead to the corrosion of masonry anchors, lintels and relieving angles, water damage to interior finishes, and the creation of mold or mildew on the non-masonry surfaces. The installation of through-wall flashing is an effective means of removing excess moisture from masonry wall systems when not originally included in a building's construction.
When, by inspection, it is determined that through-wall flashing would provide the necessary correction for these problems, the suitable material will be selected, with consideration given to the issues of durability, compatibility and ease of installation, as well as cost. Flashing is typically designed for installation at window and door lintels, and continuously along the relieving angles between building floors. There are many options available when specifying a through-wall flashing material and a satisfactory balance between budget and performance can be achieved.
All flashing will then be installed according to corresponding industry guidelines and once in place will provide an effective means of expediting accumulated moisture from a building's masonry wall system for years to come.
Cleaning
The accumulation of dirt and pollutants on masonry, to say nothing about graffiti and vandalism, can cause damage to a building's overall appearance. Cleaning would also be required if coating of the masonry surface is contemplated.
The masonry can be cleaned to its original color or tone with the use of restoration cleaners and high-pressure water. With the number of environmentally friendly cleaners from different manufacturers available, it is easy to select the best product for your project.
Water repellents
Masonry structures, when properly constructed and maintained, are quite resistant to moisture penetration by themselves. Added protection may be obtained through the application of high-quality water repellents.
Although not designed to prevent all instances of moisture penetration, they do aid in lessening the amount of water absorbed into the masonry wall systems. The effective use of these materials, however, requires that the masonry be in good condition and void of cracks or other deterioration.
Estimated life expectancy of materials exposed to normal weathering
Material |
Use |
Estimated Life Years |
Brick |
Walls |
100 or more |
Finishes |
||
Sealers Silicone Paint |
Damproofing Damproofing Waterproofing |
1 - 5 1 - 5 3 - 5 |
