- Schools, commercial and institutional buildings
- Buildings requiring a high fire rating
- Noisy environments
- Areas with frequent rainfall
- Tough, beautiful brick exterior over a structural backup system
- Extremely durable, long-lasting wall system
- Minimal long-term maintenance
- Great design flexibility
- Concrete block backup acts as the structure, with vertical and horizontal reinforcement grouted into place
- Less flexible, less prone to rot and rust than a wood-stud or steel-stud backup wall
- Cavity system inherently weatherproof – great for moist environments
- Excellent insulating value and heat capacity
- Inherently fireproof with fire ratings ranging from 3-5 hours
- Great for noisy environments – naturally absorbs sound
- One trade erects both the structural and skin layers of the wall
- Lower life cycle cost offsets higher initial investment
- This substantial wall system may require larger foundation
- Backup: Lightweight plain gray concrete block (CMU), 8” x 8” x 16” (nominal), vertical reinforcement @ 32” on center.
- Horizontal Reinforcement: 9-gauge joint reinforcement/pintle wall ties at 16” on center (every other course) Reference: Colorado Masonry Systems Design Guide, Chapter 6, Table 6-4
- Veneer: Modular clay brick (nominal 4” x 2-5/8” x 8”)
- Drainage cavity: 4” cavity (2” insulation + 2” air gap)
- Insulation: 2” extruded polystyrene rigid insulation board Reference: Colorado Masonry Systems Design Guide, Chapter 8, Table 8-3
- Flashing: Self-adhered bitumen flashing with 1” metal drip edge Reference: Colorado Masonry Systems Design Guide, Chapter 6, Shelf Angle Flashing Options, Fig.6-3 (Option 2)
- Mortar: Type N, Portland cement/lime, plain gray
- Joints: Concave tooled
- Fire Rating of a multi-layered cavity wall = (Rating1 0.59 + Rating2 0.59 + 0.3)1.7
- Brick veneer + CMU Grouted @ 32” on center: 4 hours
- Brick veneer + fully grouted CMU: 4 hours
Reference: NCMA TEK Manual 07-01D
Reference: BIA Tech Note 16
- Brick veneer + CMU Grouted @ 32” on center: 70 pounds per square foot
- Brick veneer + fully grouted CMU: 105 pounds per square foot
- STC = (weight of wall)0.233 x 21.5
- CMU grouted @ 32” on center: STC = 57.86 dB
- CMU fully grouted: STC = 63.59 dB
- R-value: 13.71
- Outside air film 0.17
- Brick veneer 0.44
- Air gap 0.97
- 2” EPX board 10.00
- 8” CMU, grouted at 32” on center 1.45
- Interior air film 0.68
- TOTAL 13.71
- Place rigid-board insulation in the drainage cavity to maximize interior usable space and take advantage of the huge thermal mass provided by the masonry backup system.
- Brick veneer expands as it ages, whereas concrete block shrinks. Don’t forget to detail expansion joints in the brick veneer and control joints in the concrete block backup.
- Shelf angles may not be required for veneer support at every floor line. Cut down on the number of shelf angles to save money and simplify construction.
- Simplify construction by requesting to use the same mortar type on the veneer as the backup. Type N is usually fine for both, except in high seismic zones where Type S is required.
- Do your best job to keep mortar from filling the cavity space. The cavity needs to be open enough to permit water to drain down onto flashing below.
- If you are doing high-lift grouting, a rebar positioning device can help you keep the rebar in place where it will give maximum structural effect. See example.
- Use 16” wide rigid insulation that will fit neatly between the eyes of the horizontal reinforcing. Use the legs of the pintles to hold the insulation board securely against the CMU back-up, leaving the cavity open for drainage.
- If the design calls for insulation in the cavity, you might consider using full sheets of insulation paired with standard two-piece adjustable anchors screwed to the face shells of the CMU instead of using pintle/eye horizontal reinforcing to tie the two wythes of the wall together. This system allows you to use large sheets of rigid insulation and minimizes the amount of time spent taping seams between pieces of insulation. Reference: Colorado Masonry Systems Design Guide, Chapter 6, Table 6-4
Self-Adhered Flexible Flashing: This tough, flexible flashing strip comes with a removable release liner for easier installation. The liner MUST be removed to allow the sticky layer of the flashing to self-heal around any punctures from nails or screws. If the sticky layer of the flashing is bitumen, hold this flashing at least ½” from the edge of the masonry so that the tar layer does not melt and form ugly black drips on the face of the wall. Bitumen-based flashing is often paired with a metal drip edge which can be exposed to sunlight. This flashing will stick to masonry, concrete, gypsum, wood, or steel.
Base of Wall —Flash Vent Self-Adhering SS Flashing with Drip Edge
Roof to Wall Parapet Detail —York 304 SA Self-Adhering Stainless Steel Flashing (view from face of wall)
Roof to Wall Parapet Detail —York 304 SA Self-Adhering Stainless Steel Flashing (view from roof)
Ladder-Eye Horizontal Reinforcing: Attaches the brick veneer to the horizontal reinforcing in the back-up CMU wall. The hooks of the pintles allow some vertical adjustability if the bed joints in the veneer do not exactly align with the bed joints in the CMU behind it. The horizontal legs of the pintles have been tested to transmit a lateral force of over 200 pounds per lineal foot from the veneer to the structural CMU wall behind it. This system allows the builder to fit 16” tall rigid insulation between the projecting eyes of the horizontal reinforcing.
Masonry Anchors & Ties
Barrel Veneer Ties: Designed to minimize thermal transfer. The thickness of the barrel resists bending, and the single screw allows the anchors to be installed quickly. These ties can be screwed into concrete, CMU or wood studs. The factory-installed EPDM washers seal the penetration the screw makes in the air/vapor barrier. Using this style of masonry anchor will minimize the amount of tape used to seal joints in the rigid insulation.
These drawings contain technical information on masonry wall systems. They provide some of the basic information required to properly design and detail these systems. This information does not cover all designs or conditions. The information presented illustrates only principles that are involved. The information contained here is based on the available data and experience of the technical staff of Atkinson-Noland & Associates and Rocky Mountain Masonry Institute. The information should be recognized as suggestions which, if followed with good judgement, should produce positive results. Final decisions on the use of information, details and materials as discussed in this guide are not within the purview of Atkinson-Noland & Associates or Rocky Mountain Masonry Institute. Final choices must rest with the project designer, owner, or both.