This week we looked at five of the most common frequently asked questions (FAQ’s) related to historic brick masonry restoration in Washington DC.  Those questions and subsequent answers got into discussions on restoration and preservation, repointing and tuckpointing, and the technical areas of best practices of care for historic masonry structures and facades.     

A link to last week’s article can be found here.

Today we continue that discussion by looking at a new set of 5 of the most common frequently asked questions. Today we will talk about:

We start today’s discussion with FAQ #6 below, where we left off last week:

6. What are the long-term consequences of neglecting the need for repointing in historic brick masonry?

In the long-term, unmitigated or untreated mortar deterioration will lead to catastrophic failure of a building, eg. collapse. The brick walls of historic row homes in The historic neighborhoods of Washington DC such as Capitol Hill, Georgetown, and Dupont Circle, are structural walls.   Unlike interior non-bearing partitions, structural walls support the dead loads and live loads of a building.   The dead load of a building is the mass and weight of the building itself, whereas the live load of a building is the weight of furniture, furnishings and the inhabitants or users of a building.

While we use the word catastrophic, and this kind of major failure is in fact catastrophic, you can often see obvious signs of failure slowly happening to a building long before a building starts to collapse.  In a past article, at the following link,we looked at a collapsed rowhome rear facade:

Learning Masonry Structure Anatomy From Old Ruins – Part I

In this fascinating case study, you learn about the foundation and load path of a typical historic brick rowhome and how the economic blight in America’s urban centers affected the choices related to mid-century restoration of defunct systems, often rendering fireplaces abandoned and unrepaired, especially after more modern and contemporary HVAC systems became available.  The building in the case study was vacant and unprotected for years.  Over time the brick mortar joints became neglected and deteriorated to the extent that the walls first experienced lateral deflection.   Repointing or tuckpointing and restoration of the historic brick mortar could have reversed the natural effects of aging.  Overtime, slowly the damage became worse and worse.  It’s true that masonry deterioration generally happens very slowly, yet the process of deterioration happens at an increasing rate.  Deterioration is nonlinear.  In other words, while historic brick deteriorates slowly, it happens faster and faster.  Erosion begets yet more erosion, for example.  Disintegrating mortar leads to yet more disintegration of mortar deeper within a brick wall assembly.  The driving force of disintegration, erosion,  and deterioration of mortar are the elements of nature and mainly exposure to water and hydration. This damage happens, invariably at mortar joints.  Repointing or tuckpointing are the only way to preserve and stop the process of deterioration, but as the damage becomes extensive, it can lead to worse problems.  

The picture below shows the exterior episode of a structural brick wall in a historic building. The wall went without proper repointing for decades.   As water entered and sat within the mortar joints, through the pressures of freeze-thaw cycles, the bricks cracked and spalled.  

The damage to this particular wall is so extensive that even from a distance, the deterioration is noticeably visible.  Brick spalling refers to the gradual deterioration or flaking of the surface layers of brick masonry structures. This phenomenon primarily occurs due to the infiltration of water into the brick’s pores, especiallyin historic brick masonry like that which was commonly used over 100 years ago in Washington DC, followed by cycles of freezing and thawing. When water enters the brick, it expands as it freezes, exerting pressure on the brick’s internal structure. This repeated expansion and contraction stress lead to the disintegration of the brick’s surface layers, resulting in spalling. Additionally, chemical reactions, often the effects of which can be seen in efflorescence, between water and the minerals within the brick can indicate signs of deterioration leading to spalling. Over time, if not addressed, brick spalling can compromise the structural integrity of the masonry and cause significant degradation, making it a concern in the areas of structural failure as a result of a lack building maintenance over a long period of time.

7. How can I differentiate between a superficial cosmetic issue and a structural problem that requires repointing?

This particular question is complex, but the bottom line is that issues with deterioration at mortar joints over extended periods of time, has explained in the FAQ above, lead to significant damage and even eventual catastrophic failure.  Differentiating between a superficial cosmetic issue and a structural problem requiring repointing in historic brick masonry involves a careful assessment of several factors. First, the depth of mortar deterioration must be examined. It helps to engage a professional like Infinity Design Solutions. Superficial cosmetic issues typically manifest as minor mortar wear on the surface, often due to weathering and exposure to the elements. These cosmetic concerns may not affect the structural stability of the masonry,  at first. In contrast, structural problems are characterized by deeper mortar deterioration, potentially extending into the the area beyond the surface of the mortar joint. 

Another aspect to consider is the presence of gaps or voids between bricks. Superficial issues might involve minor gaps or cracks, primarily affecting the mortar joints’ outer layers. However, structural problems often result in more extensive gaps, voids, or even complete separation between bricks. These gaps can compromise the load-bearing capacity of the wall, making repointing necessary for restoring structural integrity.

When the mortar’s integrity is compromised at this level, it can jeopardize the stability of the entire wall.  After the mortar joints become destabilized,  secondary problems often result in lateral deflection which leads to wall collapse or stair-step cracking which leads to header failure and collapse.

In the realm of structural concerns, it’s important to understand that the mortar in historic brick masonry contributes significantly to the wall’s integral strength. Mortar joints distribute loads and provide cohesion between bricks. As erosion or deterioration progresses into the core of these joints, it weakens the overall structure. A skilled assessment, including probing the mortar joints and assessing the extent of wear, can help identify whether the issue is superficial or requires repointing for structural reinforcement. Proper evaluation and timely intervention are essential to maintain the stability of historic brick masonry structures.

The picture below shows the front facade of a historic brick building, built over 100 years ago.  

8. How does the choice of mortar type impact the durability and appearance of a repointed facade?

The choice of mortar used in repointing is critical in its effect on the longevity of a restored facade, and it involves a somewhat complex interplay of factors. Traditional historic brick mortars, often dating back a century or more, exhibited significant variation in both the types of aggregates and binders used. These historic mortars tend to be softer and more permeable compared to their modern counterparts.

The key distinction is in the binder composition of these mortars. Traditional historic mortars often used slaked lime as a primary binder, with aggregate materials like sand and sometimes even crushed shells, foubd in some coastal areas (like the Carolinas with tabby Ruins along the seaside).  These ingredients created a mortar that was relatively soft (on a structural engineering scale) and porous, allowing for flexibility and breathability. This was particularly well-suited to the older bricks and masonry materials used in historic buildings. Over time, this type of mortar could accommodate the natural expansion and contraction of bricks, with changes in weather and temperature, preventing damage due to typical shifts.

In contrast, modern mortars commonly use Portland cement as the primary binder, resulting in a mortar mix with higher compressive strength and lower permeability. While this might appear to be an improvement in terms of structural resistance, it will invariably cause potentially devastating problems when used on historic brick masonry, in the repointing or tuckpointing process, for example. The rigidity of modern mortars can be mismatched with the relatively softer and more porous historic bricks, leading to unintended consequences. When subjected to structural stresses or environmental changes, these differences in material properties can cause stress points and even damage to the historic masonry.

Moreover, modern mortars’ lower permeability,  when used in repointing or tuckpointing, can disrupt the natural breathability of historic walls. Moisture that would have been absorbed and released through the softer, more porous historic mortar can become trapped within the masonry. This can lead to increased risk of freeze-thaw damage, efflorescence, and spalling, all of which can deteriorate the bricks’ appearance and structural integrity.

In essence, while modern mortars may offer advantages in terms of strength and longevity, they must be used judiciously in the context of historic brick facades. The choice of mortar type should prioritize compatibility with the existing masonry materials and take into account the building’s specific needs. This often involves replicating the historic mortar’s composition and properties, as closely as possible, to ensure the long-term preservation of the facade. In cases where modern mortars are used, careful consideration, and possibly consultation with professionals such as Infinity Design Solutions, is helpful to mitigate potential adverse effects on historic structures.

The picture below shows a facade area where a leaking scupper head caused damage to the brick wall for years while the scupper went unrepaired.   Later, when repairs were finally made to the brick, to the right side of the scupper in the photo below, the brick was reset in place by an untrained and unskilled worker and a modern mortar was used.  Untrained or unskilled workers will often use incompatible mortars because modern mortars are available at local big box stores and compatible historic mortar is not available off the shelf at big box stores.

9. Can repointing address issues related to cracking, spalling, or other forms of masonry deterioration?

No, repointing or tuckpointing alone cannot fix problems of brick damage and deterioration such as cracking and spalling.  Repointing proactively on a timely schedule can largely prevent this type of damage from occurring, but even after damage within individual brick units happens, even where it cannot yet be seen, it cannot be fixed by simply repointing.  The only way to fix that type of damage is to replace the damaged units.  

As a side note, as we touch one here, damage can happen within the internal parts of individual brick units for a significant amount of time before those brick units even crack and/or spall or fall apart. The internal parts of a brick, once damaged from unmitigated exposure, are damaged permanently, and meanwhile the outer parts of the brick might not show that damage for years or even decades. Pointing and/or repointing or tuckpointing will not fix that damage that has already happened and even after repointing, if repointing is not done on a timely schedule, the damage that’s already happened In the past can become visually apparent after pointing happens if that repointing doesn’t happen proactively and preemptively.

The picture below shows a closer view of a different brick wall where pointing has not been managed properly. This wall should have been repointed years prior to now and in the picture below you can see the condition of those open mortar joints where the mortar has deteriorated significantly now today. In the middle of the picture there is a brick that has cracked and spalled.

10. What maintenance practices can homeowners follow to prolong the effects of a professional repointing job over time?

 There are several types of upkeep and maintenance practices that should be followed by homeowners to protect the facade of a building from damage and deterioration.   The pictures below show the work of an overzealous house flipper who added three large dormers to an attic space in a conversion to add interior square footage. The dormers did not initially account for an uninterrupted span of a gutter at the gable roof eave.  Now the only practical solution is to have four independent gutter and downspout systems.  It looks ridiculous, but it’s much better to collect and channel rainwater away from the facade.  It was a big oversight, but at least the facade is being protected.  

The next picture shows the same facade from a different angle and you can see that the original line of roof eave has been interrupted by the new dormers.

The following tips can help maintain a building for increased longevity:

1. Conduct routine inspections of your brick facade. Look for any signs of deterioration, cracks, or gaps in the mortar joints. Early detection allows for timely repairs, preventing more extensive damage.
2. Keep the brick facade clean. Remove dirt, dust, and debris regularly to prevent them from settling into the mortar joints, which can lead to deterioration over time.
3. If you need to clean the bricks, use a mild, non-acidic detergent and a soft brush or sponge. Avoid abrasive materials or harsh chemicals that can damage the mortar.
4. Ensure that your gutters and downspouts are functioning correctly. Proper drainage prevents water from overflowing and saturating the brickwork, which can accelerate mortar deterioration.
5. Trim any overhanging trees or bushes near the building. This prevents branches, leaves, or debris from scratching or damaging the brick facade.  It’s not easy to scratch a brick, but when branches grow out to the point that they are literally touching against a facade, UT can cause damage.  Imagine a heavy branch pushed against a brick facade, with the weight of the heavy truck pressing it against the bricks as the entire tree, including the mass of the trunk sways to and fro everything the wind blows.  That can be a lot of contact, even to the point of causing abrasive damage, just in a day.  Imagine if that action continues unabated, unmitigated for months or years.
6. Ensure that the ground around your building slopes away from the foundation. Adequate drainage helps prevent water from pooling around the base of the building, reducing the risk of moisture infiltration.
7. Address any cracks or gaps in the mortar as soon as they appear. These vulnerabilities can allow water to penetrate, leading to more significant problems. Homeowners can contact a professional, like IDS, for repairs.

The pictures below show an area at a window header, where a gap developed between the brick and the steel lintel after the lintel had oxidized and became dilapidated. This particular still lintel is the structural reinforcement which supports the flat header.     

This is an example of a very expensive repair that could have simply been avoided by routine maintenance of upkeep.

1. If you’re considering painting your brick facade, choose a breathable masonry paint or lime wash. Avoid waterproof coatings that can trap moisture and exacerbate deterioration.
2. Periodically consult with professionals experienced in historic masonry preservation like Infinity Design Solutions. They can conduct assessments, provide guidance on planning and maintenance, and perform necessary repairs.
3. While some minor maintenance tasks can be done by homeowners, avoid using low skill contractors for repointing or major restoration work. Incorrectly executed repairs can do more harm than good. Consider specialists, like Infinity Design Solutions for extensive mortar or brickwork issues.
4. Recognize that repointed mortar joints will not last indefinitely. Depending on various factors, including climate and exposure, repointing may be needed again in the future. Plan for this as part of your long-term maintenance strategy.

By following these maintenance practices and staying vigilant, homeowners can extend the life of a professional repointing job, ensuring the continued preservation of their historic brick facade. Regular care helps protect the building’s structural integrity and retains its historical character.