Exploring Blind Side Facing Masonry Walls: Key Considerations and Techniques
We’re starting a series today looking at issues of blind side facing Masonry walls. The blind side facing wall is a portion of a wall that cannot be accessed when building a brick partition or facade. You may have never heard of anything like this before, but there’s a chance here in Washington DC, you’ve walked right past a brick wall that was never intended to be exposed. You may have noticed significant blobs of mortar that has oozed out between the joints and never been cleaned or struck to have a intended finish.
It looks very rugged and rough, and since it was never really intended to be exposed, it wasn’t considered a problem at the time of the original construction. In most cases, most buildings like the one below were built side by side next to another existing building over 100 years ago and in this particular case, those buildings weren’t built together.
They were built separately, but touching, built at different times. The side of the building shown was built after the previous building was fully built. Instead of just using the neighboring building’s wall as the new building’s interior wall, they built their wholly owned wall of brick next to it. But as they built the brick right next to another building, they didn’t have the ability to strike and clean those mortar joints.
Joint striking, aka tooling, is the process of finishing the mortar joints between bricks after the mortar has been applied and partially set. A tool is used to shape the mortar, modifying the appearance of the brick joints and improving its performance, especially in an exterior exposed position. The most common types of joint profiles include concave, flush, raked, and weather-struck joints. Each profile has specific implications to how water runs off the wall and how shadows are cast on the brick surface.
Concave and weather-struck joints are popular for their ability to shed water most effectively which reduces the anount of water infiltration and damage. Raked joints, where the mortar is recessed, create a more visually pronounced shadow effect but are more susceptible to water penetration. Each rig joint basically creates a little ledge at the top of the brick. As precipitation lands on top of each of those little ledges, that water sticks around for a longer amount of time which leads to higher degrees of permeation which can have negative consequences over many years, especially through freeze-thaw cycles.
Joint striking compacts the mortar against the bricks, which improves the overall bond of each individual mortar joint. This leads to overall greater structural integrity of the brickwork. Proper tooling / striking needs to be done when the mortar is firm but not fully hardened. If it’s done too early it’ll be just smooshing around material that can’t be formed or shaped yet. If it’s done too late, it won’t be able to modify and shape the actual surface of the mortar because the mortar will already be too hardened.
As the decades went by, both buildings changed significantly and the building shown below has been modified and modernized in many ways, but the building that was originally next to it on the left side has since been razed and demolished and is now gone.
The next picture below shows how much closer view. In the portion of the wall in the right hand side of the photograph, you can see a portion of the front facade. This brick is a different type of brick, a darker red, and the mortar joints are in much better shape and condition. It’s not just that the mortar joints at the front wall have been restored and repointed or tuck pointed in the years after the original construction, but also that the front facade wall was built much better, even in the beginning approximately 100 years ago
The front facade wall, in contrast to the side wall, was always intended to be a finished exposed surface. The picture below shows the view from the side but at the front of the side where you can see the front facade front course of bricks. At the time of the original construction, the masons who built this building couldn’t access the edge shown in the picture below. Instead of filling and striking the joints completely, at the blind side, there are some inevitable voids. As the adjacent building is now gone, that void is open and it looks like pedestrians have walked by or loitered around and jammed little pieces of trash into the interstitial space.
If you look at the picture below, you can see some of the kinds of issues to expect when you cannot actually reach a portion of a wall. This is at the edge of the front facade of the wall. Here at the time of the original construction the edge of the brick, shown in the picture below, would have been against an adjacent brick of the adjacent building. From the joint of the brick, on the side, the rear portion of that same bed joint of mortar was not accessible and had not been tooled and smoothed. As well, there is a recess on the inside area of that mortar joint.
We can Help
Our company focuses on historic restoration more than modern building upkeep, maintenance, and construction, but our company understands both types of construction very well and a full picture well-rounded approach is needed in any niche in the construction industry. Although we focus on historic restoration, repointing, tuckpointing and historic brick repair, our company also has technical knowledge and competencies in the areas of modern and contemporary construction as well as we become one of the leaders in that area of the market today. Understanding both historic and modern or contemporary construction is useful because both aspects help understand the challenges and potential solutions for challenges in building science and construction.
We can help with a variety of historic masonry restoration needs and upkeep, from modest tuckpointing and or repointing to complicated and extensive historic masonry restoration. ]Infinity Design Solutions is a historic restoration specialist contractor specializing in both historic masonry restoration such as tuckpointing our repointing, and brick repair. If you have questions about the architectural details or facade of your historic building in Washington DC, reach out and say hello and if we can help we’ll be glad to assist you. You can email us or call us on the telephone at the following link: contact us here.
