Chimney Tuckpointing and Repointing

Rooftop chimneys are exposed to harsher environmental conditions compared to the lower parts of a building, leading to accelerated deterioration. The primary reasons for this accelerated deterioration are as follows:

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1. Exposure to Extreme Temperature Fluctuations: Rooftop chimneys experience more significant temperature swings due to direct exposure to sunlight and wind. These temperature fluctuations cause the masonry materials to expand and contract repeatedly, leading to cracking and spalling of the brickwork and mortar joints.

2. Increased Moisture Penetration: Rooftop chimneys are more susceptible to moisture penetration from various sources, including rain, snow, and condensation. This moisture can seep into the masonry units and mortar joints, causing further deterioration through freeze-thaw cycles and efflorescence.

3. Wind and Weather Exposure: Rooftop chimneys are directly exposed to wind, rain, and other weather elements, which can erode the mortar joints and cause loosening or displacement of bricks over time.

4. Lack of Maintenance: Chimneys on rooftops are often overlooked or difficult to access, resulting in a lack of regular maintenance and upkeep, which can exacerbate existing problems.

To address the deterioration of rooftop chimneys, our company undertakes a comprehensive approach to repair and restoration, including at least some of the following procedures:

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1. Counter Flashing and Base Flashing Repair: We can repair the counter flashing and base flashing around the chimney to ensure proper water drainage and prevent moisture penetration. This may involve replacing deteriorated flashings or resealing them to the roofing membrane.

2. Repointing: Deteriorated mortar can be removed from the joints between the bricks and re joints are thenrepointed with new, compatible mortar. This process improves the structural integrity of the chimney and prevents further water infiltration.

3. Flaunching: The flaunching, the sloped mortar at the base of the chimney can be repaired or replaced where it meets the roof. Proper flaunching is needed for directing water away from the chimney and preventing moisture penetration.

4. Crown Repair: The crown, or the top portion of the chimney, is often exposed to the harshest conditions. We repair or replace damaged or missing crown bricks, ensuring proper water shedding and preventing moisture entry.

5. Chimney Cap, Spark Arrestor, and Flue Tile Repair/Replacement: We can survey and repair or replace chimney caps, spark arrestors, and flue tiles as needed. These components protect the interior of the chimney from water entry and can prevent sparks or debris from escaping.

During these repair processes, we often use specially formulated appropriate masonry materials and techniques to match the existing brickwork and maintain the historic integrity of the structure. Proper installation of flashing, counter flashing, and sealants is also needed, in many cases, to ensure long-term watertightness and prevent future deterioration.

Regular condition checkups and timely maintenance of rooftop chimneys are needed to address any issues before they escalate and cause more extensive and costly damage.

Exposed Blind Wall Repairs

The term "blind wall" is commonly used to describe masonry walls that were originally built against an existing structure and were never intended to be exposed on one side. These walls are often found in historic buildings, particularly in dense urban areas like Capitol Hill in Washington, D.C.

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When neighboring structures are removed or their height is lowered, these blind walls can become exposed, revealing a rough and unfinished surface with unstruck mortar joints and voids. These exposed blind walls face unique challenges and require specific repair and restoration techniques.

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At the rooftop level, where we generally work, the exposure of these blind walls is even more severe due to the harsh environmental conditions and lack of protection from adjacent structures. The rough and unfinished surface of the exposed blind wall can be susceptible to moisture penetration, freeze-thaw cycles, and accelerated deterioration.

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To address the repair and restoration of exposed blind walls, particularly on rooftops, our company employs the following techniques:

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1. Filling Voids: We may fill voids or gaps in the exposed masonry surface with compatible mortar or repair materials. This process helps to create a more uniform and weather-resistant surface, preventing moisture penetration and further deterioration.

2. Repointing: In areas where the mortar joints are severely deteriorated or missing, we may remove the existing mortar and repoint the joints with new, compatible mortar. This process improves the structural integrity of the wall and deters water infiltration.

3. Surface Preparation: Before any repair work, we may need to clean and prepare the exposed masonry surface to allow for proper adhesion and bonding of the repair materials.

4. Coatings or Sealants: In some cases, we may apply coatings or sealants to the exposed blind wall surface where the wall meets an adjacent roof system. These coatings help to protect the masonry from moisture intrusion while still allowing the wall to breathe and prevent further deterioration.

5. Flashing and Coping Repair: If the exposed blind wall extends above the roofline, we may need to repair or replace any deteriorated flashing, coping stones, or other water-shedding elements to prevent water infiltration and protect the masonry below.

Throughout the repair process, we pay close attention to matching the existing masonry materials and techniques to maintain the historic integrity of the structure. Proper installation of flashing, sealants, and coatings is also crucial to ensure long-term protection and prevent future deterioration of the exposed blind wall.

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Regular checkups and timely maintenance are essential for exposed blind walls, as they are often overlooked and can be susceptible to accelerated deterioration due to their exposed and unprotected nature, especially at the rooftop level.

Scam Pointing & Joint Caulking Removal

Scam pointing or cover-up pointing is a term used to describe the practice of smearing a thin layer of incorrect mortar over existing brick joints without properly raking and removing the original deteriorated mortar. This practice is often favored by real estate professionals and property flippers because it provides a seemingly new appearance at a minimal cost. However, it is considered an improper and unacceptable method, as it fails to address the underlying issues and can exacerbate existing problems.

Our company is frequently hired to remove this improper cover-up pointing and perform proper repointing work. Scam pointing can cause several problems and exacerbate underlying issues, including:

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1. Lack of adhesion: The new mortar layer is simply smeared over the existing joints without proper preparation, leading to poor adhesion and a high risk of future cracking, crumbling, or complete separation from the bricks.

2. Moisture entrapment: The original deteriorated mortar remains in place, trapping moisture within the joints. This trapped moisture can lead to further deterioration of the bricks and mortar, as well as potential freeze-thaw damage in colder climates.

3. Incompatible materials: The mortar used for scam pointing is often not compatible with the existing masonry materials, leading to differential movement, cracking, and potential structural issues over time.

4. Concealment of underlying problems: Scam pointing merely covers up existing issues, such as cracked or spalled bricks, instead of addressing and repairing them properly. This can lead to further deterioration and more extensive damage in the long run.

5. Accelerated deterioration: The improper application of the mortar layer can create pathways for water infiltration, causing accelerated deterioration of the masonry and potential damage to the interior of the building.

6. Shortened lifespan: Scam pointing is a temporary and cosmetic fix that does not address the root causes of deterioration. As a result, the lifespan of the masonry is significantly shortened, and more extensive repairs or complete repointing will be required sooner than if the work had been done properly initially.

To improve the longevity and structural integrity of masonry structures, our company follows proper repointing procedures, which involve carefully raking out the deteriorated mortar to a specified depth, cleaning the joints, and installing new, compatible mortar in accordance with industry standards and best practices. This approach addresses the underlying issues, ensures proper adhesion and compatibility, and provides a long-lasting and durable repair.

Regular maintenance and checkups are needed to identify and address any issues with masonry joints before they escalate and require more extensive repairs. By avoiding scam pointing and opting for proper repointing techniques, property owners can protect their investments and maintain the aesthetic and structural integrity of their historic masonry buildings.

Loose Brick at Coping and Parapets

Brick can become loose underneath parapet copings due to various factors, including age, weathering, and improper construction techniques. In some cases, wood nailers (as shown in the photo above) were originally set into the brick walls to secure the historic copings. While these wood nailers might remain in place, the surrounding mortar and brickwork can deteriorate over time, leading to potential instability and the need for repairs.

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One common issue is the deterioration of mortar at the interface between the wood nailers and the brick courses. Prolonged exposure to moisture and freeze-thaw cycles can cause the mortar to crack, crumble, or separate from the bricks and wood nailers. Additionally, the wood nailers themselves may rot or decay, further compromising the structural integrity of the parapet coping and the top courses of brickwork.

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In such cases, our company is often hired to rebuild the top courses of bricks at the exterior demising walls and/or interior party walls. This process involves carefully removing the loose or deteriorated bricks and mortar, checking and potentially replacing any damaged wood nailers, and then rebuilding the top courses using compatible bricks and mortar.

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The causes of loose bricks underneath parapet copings can vary, but some common factors include:

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1. Moisture infiltration: Water penetration through cracks, defective flashing, or other openings can saturate the masonry and cause the mortar to deteriorate, leading to loose bricks.

2. Freeze-thaw cycles: In colder climates, the repeated freezing and thawing of trapped moisture within the masonry can cause expansion and contraction, leading to cracking and eventual loosening of bricks.

3. Thermal movement: Differential thermal expansion and contraction between the brick masonry, wood nailers, and coping stones can create stress and cause the mortar to break down over time.

4. Improper construction techniques: If the original construction did not follow proper methods for securing the coping stones or embedding the wood nailers, it can lead to premature failure and loose bricks.

5. Age and weathering: Over time, even well-constructed masonry can deteriorate due to exposure to wind, rain, UV radiation, and other environmental factors.

To address this issue, our company can follow a process that includes checking the exposed portions of the parapet wall and coping system, to identify the extent of deterioration where observable, and rebuilding the affected areas. Repaired flashing details, compatible historically accurate or comparable mortar ratios, and / or appropriate anchoring techniques are used to restore, rebuild, and or repair areas of this type of deterioration and damage.

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Regular maintenance and check ups can hep to identify and address any problems with loose bricks or deteriorated mortar before they escalate and potentially compromise the structural integrity of the parapet walls and copings.    

Structural Failures

Structural failures highlight the importance of addressing deteriorated historic masonry and old brick mortar joints before they lead to structural failures, such as the collapse of walls and chimneys above roofs. In the Capitol Hill neighborhood, we often encounter extremely and excessively deteriorated areas of historic brick masonry above the rooftops of historic buildings. This highlights the critical need to work with a contractor like GL Barnhart Construction to maintain and monitor the condition of a building through routine maintenance and condition surveys or check-ups.

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Historic mortar, especially in areas above flat rooftops, is prone to accelerated breakdown due to prolonged exposure to the elements over many years. The subcomponents of lime mortar, such as the lime binder, aggregate, and any additives, can deteriorate at different rates when subjected to environmental factors like moisture, freeze-thaw cycles, and ultraviolet radiation.

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One of the primary causes of mortar breakdown is the presence of moisture. Water can penetrate the mortar joints through various means, including rain, condensation, and capillary action from the surrounding masonry units. Once inside the mortar, this moisture can dissolve and leach out the lime binder, weakening the mortar's bond and cohesion.

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Additionally, the repeated freezing and thawing of trapped moisture within the mortar joints can cause significant damage. As water freezes, it expands, creating internal stresses that can lead to cracking and spalling of the mortar over time.

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Exposure to ultraviolet radiation from sunlight can also contribute to the deterioration of historic mortar. UV rays can degrade the organic components within the mortar, such as hair or other fibers used as reinforcement, leading to a loss of strength and integrity.

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Furthermore, the aggregate used in historic mortars, often comprising sand or crushed stone, can also be affected by weathering processes. Prolonged exposure to moisture and freeze-thaw cycles can cause the aggregate particles to become loose or dislodged from the mortar matrix, further compromising the overall strength and durability of the mortar joints.

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As the mortar joints deteriorate, they can no longer adequately transfer loads between the masonry units, increasing the risk of structural failures. Loose or missing mortar joints can lead to the displacement of individual bricks, potentially causing partial or complete collapse of walls, chimneys, or other masonry structures above rooftops.

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By working with a contractor like GL Barnhart Construction for routine maintenance and condition surveys, property owners can proactively identify and address any issues with deteriorated historic masonry before they escalate into more severe and costly problems. Regular monitoring and timely repairs can help preserve the structural integrity and historic character of these buildings for generations to come.

Fixing Mismatched Mortars

In another section, here in our service page, we talked about the problems associated with cover-up or scam pointing. This problem is similar but slightly different. Often the issue isn't really about flippers trying to cut a corner, sometimes it is just that workers don't receive enough training before striking out on their own and when asked to repoint an area of historic brick will just use mortar from a big-box store. That mortar is incorrect and will lead to massive, devastating, and destructive problems.

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When workers without sufficient training or experience in historic masonry may attempt to repoint areas of historic brick using readily available mortar from big-box stores. This mortar is often incorrect for historic applications and can lead to severe problems.

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When inappropriate mortar is used for repointing historic brickwork, it can create compatibility issues and accelerate the deterioration of the masonry. Modern mortars, such as those found in big-box stores, are typically formulated with high Portland cement content, making them harder and less permeable than the original historic lime-based mortars.

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The use of these harder, less breathable mortars can cause several problems:

1. Increased stress on the masonry units: The harder mortar is less flexible and cannot accommodate the natural movements and thermal expansion of the brickwork, leading to cracking and spalling of the bricks over time.

2. Moisture entrapment: The less permeable mortar can trap moisture within the masonry assembly, leading to potential freeze-thaw damage, efflorescence, and accelerated deterioration of the bricks and mortar joints.

3. Incompatibility with historic materials: The chemical composition and physical properties of modern mortars may be incompatible with the historic bricks and any remaining original mortar, causing further deterioration and potential structural issues.

In cases where inappropriate mortar has been used for repointing historic brickwork, there are steps that can be taken to help improve the situation and mitigate further damage. One effective approach is selective repointing with proper mortar of a lower compressive strength, generally lime mortar.

Lime mortar, which was commonly used in historic masonry construction, is softer and more permeable than modern cement-based mortars. By selectively removing the inappropriate mortar and repointing with a compatible lime-based mortar, several benefits can be achieved:

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1. Improved breathability: Lime mortar allows for the natural movement of moisture through the masonry assembly, reducing the risk of moisture entrapment and associated damage.

2. Flexibility and compatibility: Lime mortar is more flexible and compatible with historic bricks, accommodating thermal and structural movements without causing excessive stress on the masonry units.

3. Preservation of historic character: The use of lime mortar helps maintain the historic appearance and integrity of the masonry, ensuring a faithful restoration or repair.

It's important to note that the selective repointing process should be carried out by experienced professionals who understand the unique requirements of historic masonry and can properly match the composition, color, and texture of the new lime mortar to the existing brickwork.  By addressing the issue of inappropriate repointing and employing proper techniques with compatible materials, we can help preserve the structural integrity and historic character of these Capitol Hill buildings for years to come.