Most people are familiar with the advantages of masonry as an excellent, cost-effective, and sustainable building material. However, there is a lot more to it than meets the eye! Per code, lintels cannot bear on brick above certain heights in multifamily brick veneer buildings, so shelf angles are installed on each floor. These are more complex things to install!
A veneer is a nonstructural facing of brick, stone, or concrete masonry material securely attached to a wall or backing. Pro Angle Masonry Charleston provides the exterior finish for a building and transfers out-of-plane loads for approval. The license may be a masonry wall or a framed backup wall of wood or steel studs for veneers that support out-of-plane loads. For masonry veneers helped out-of-plane, TMS 402-163 requires anchoring the surface to the backing using either wood ties or masonry anchors. Masonry anchors are fastened to the backup wall framing through the sheathing, and wood ties are typically attached directly to the wood framing.
In operative stonemasonry, the builder’s square was an essential tool to verify that the sides of a cut stone were truly square and that they met the square’s “true right angle.” Freemasonry has adopted this symbol as one of its most important and recognized emblems, representing a morality that emphasizes truthfulness, fairness, and adherence to established boundaries. The compass represents a sense of direction and balance and serves as a reminder that Freemasonry’s teachings can help one navigate life’s journey easily.
The height of a brick wall is usually limited to 30 ft from the foundation to the top of the wall or 38 ft from the bottom of a gable to the top of the roof. Brick above these limits must be supported by lintels, provided on each floor where a lintel spans an opening. Depending on the type of construction, lintels may be loose or precast concrete lintels for appearance or galvanized steel lintels for economy.
For masonry above the maximum height limits, a system of shelf angles is required. Shelf angle design is important, and it is recommended that a preconstruction meeting be held to discuss the details of the masonry anchoring system. This meeting can ensure that all parties understand the requirements and expectations, including the condition that a gap be left on the underside of any lipped brick above a shelf angle.
This gap allows insulation to run continuously from the foundation to the floor line, minimizing thermal bridging and improving a building’s energy performance. A hole also makes installing fire-rated flashings at the wall and roof junction easier.
Concrete masonry units contribute strength, durability, fire resistance, energy efficiency, and sound attenuation to wall systems. They are available in a wide range of shapes and sizes. Various finishes and architectural treatments enable masonry to achieve many aesthetic and functional goals. The concrete masonry materials used to construct a structure are selected to achieve the desired performance characteristics.
Brick is a non-load-bearing cladding material that provides a finished exterior to a wall. Veneers transfer out-of-plane loads to the backing wall but do not add to the load-resisting capacity of the wall system. The surface is secured to the backing by lintels or supports attached to noncombustible framing.
An engineer sizes lintels and shelf angles to meet the steel design code requirements, including stiffness, to minimize masonry cracks. They are also designed to limit deflection between support points to l/600 or 0.3. Over openings, the lintels must be supported by a stiff, continuous member intended to limit the deflection of the wall wythe to l/600 or 0.1 in.
Masonry anchors are welded to the lintels or supports and may be corrugated sheet metal, wire, joint reinforcement, or adjustable. Building codes often restrict the use of certain anchor types. See TEK 12-1B, Anchors and Ties for Masonry (ref 9), for additional information on the requirements for anchors.
The vertical run of most Masonry Anchors, whether they are Rod Anchors, sometimes referred to as weld-on wire ties or Slotted Channel anchors, is approximately 5 in. This length was chosen to maximize the likelihood of matching the vertical run of the Masonry Anchor with the height of a mortar joint. The Masonry Anchor should not be tilted at an angle to the vertical as this will decrease the steep run and lessen the likelihood that it will match up with the mortar joint.
Experienced masons have found that they can lay about five times more blocks when working to a mason line than when using only their straightedge. A mason line is any device that can support the mason while laying blocks and ensure that partnerships are straight, plumb, and at the correct height. The corner pole is one type of mason line used in concrete block walls. The mason line should be checked frequently to ensure it is taut and will not pull out during the construction of a long course.
The design of vertical support elements for anchored masonry veneer is critical to minimizing cracking within the surface. Typically, galvanized-steel loose lintels for larger openings are used, while shelf angles (see detail below) are provided at other locations. These components are designed to minimize deflection under uncategorized dead and live loads. They must also be capable of accommodating movement provisions between the backup wall structure and the masonry veneer, which are required by code.
Most professionals are familiar with the need for relief angles to support brick veneer with wood and steel stud-framed walls at certain intervals. These angles, which are welded to the masonry backup wall system, are required per code for cladding over 30 feet in height.
For masonry walls, the frequency of these angles depends on several factors, including the type of masonry used, moisture control, and movement provisions. In addition to the issues mentioned above, these support members must be capable of resisting both the shear and flexure loads applied at these locations.
This is why it is important for structural engineers to carefully consider the construction of these support structures and their placement within a building. It includes determining the proper frequency of these angle supports and ensuring that they are placed in a location that will not interfere with the installation of any interior finishes, such as wood flooring.
To ensure the integrity of these supports, they should be installed with a minimum clearance to the underlying construction of 1/16 inch (1.6 mm). In most cases, this clearance is achieved by using an angle cut to a length equal to the maximum depth of the masonry veneer at that course level.
Additionally, it is critical that the masons properly size the bricks for the last course under the relief angle. In this case, the architectural drawings did not include a gap dimension under the curve, so the masons assumed there was no need to leave a space for thermal expansion. It was a costly mistake that could have been avoided by conducting preconstruction meetings with the team.
Masons perform various technically innovative masonry projects daily, from routine maintenance to rebuilding after a major failure or restoration of a historic structure. Our teams have the knowledge, skill, and staff to complete every project with industry standards met or exceeded for structural viability and aesthetics.
Lintels (or shelf angles) are horizontal supports, usually made of steel in commercial buildings, spanning window or door openings. These are very important to the integrity of the masonry walls. If not properly maintained, the fence will sag or skew, creating a dangerous condition for pedestrians and a risk of falling bricks and debris.
Lintels are often not galvanized in older structures, speeding up deterioration. Over time, they can rust and, if left untreated, will eventually fail, so they need to be periodically checked and replaced. When a lintel fails, it is often the cause of cracking in the brick-and-mortar joints.
The good news is that if the steel is only mildly corrupted, it can be refurbished and re-used, saving an expensive replacement cost. A simple routine check performed by a specialist in masonry restoration every 2-3 years is generally sufficient to detect deterioration and determine whether the steel is viable for continued use.
Relief angles are also critical to the overall structural stability of brick veneer wall systems. They must be provided per code for wood and steel stud wall construction at certain intervals. Often, these are omitted during installation as contractors assume they are not needed. This assumption needs to be corrected, and the resulting failure of these crucial supports can be disastrous.