Ch. 28 and 29 Review Questions
With the help of a sketch, illustrate the anatomy of PB EIFS. Also, explain what backwrapping is and where it is used in EIFS cladding.
- Gypsum, Stud/Insulation, Glass-Mat-Faced Gypsum, Air-Weather Retarder, EPS (foam insulation), Fiberglass Reinforcing Mesh, Base Coat, Finish Coat - Backwrapping is the process of wrapping the terminal edges of insulation (vulnerable areas, such as the foundation and around openings) with reinforcing mesh.
Using sketches and notes, explain the anatomy of an insulated sandwich precast concrete curtain wall panel.
- Outer Concrete, Rigid Plastic Foam Insulation, Inner Concrete - Ties embedded in concrete - Reinforcing Rod
With the help of sketches and notes, explain the support system of a precast concrete curtain wall panel.
- Supported using steel tube or W-Sections embedded in the precast wall panel connect to the bearing plate embedded in the spandrel beam. - Leveled to proper height using leveling shims - Tiebacks connects with a slotted clip angle attach to an anchor embedded in panel and a coiled ferrule embedded in beam
Sketch a split-tail anchor, showing the material it is made of and its function in a stone-clad wall.
- Used to secure stone veneer to backup wall - Made of stainless steel
Using sketches, explain the commonly used shapes of precast concrete wall panels.
- Window wall panels - Spandrel panels - Spandrel plus infill panels
Using sketches and notes, explain the adjustability requirements of anchors used in a brick veneer wall assembly.
Anchors require adjustability in the vertical and horizontal directions. Anchors should limit movement perpendicular to the backup wall.
Using a sketch, explain the purpose of a (a) bonding pad and (b) flex anchor in a GFRC panel.
Bonding Pad: - Prevents Bonding - Reduces Stresses - Allows for Movement Flex Anchor: Panel Stability: The flex anchor helps to stabilize the GFRC panel and prevents excessive movement or deflection. It provides a secure connection between the panel and the supporting structure, ensuring that the panel remains in its intended position and does not shift or deform under wind loads or other forces. Load Transfer: The flex anchor transfers the load applied to the GFRC panel, such as wind loads or self-weight, to the supporting structure. It helps distribute the load across multiple anchors, reducing the stress on each individual anchor point. Flexibility: As the name suggests, the flex anchor has a certain level of flexibility or movement allowance. This flexibility accommodates the natural expansion and contraction of the GFRC panel without compromising the overall structural integrity. It allows the panel to move slightly while maintaining a secure attachment to the support system.
Discuss the pros and cons of using a CMU backup wall versus a steel stud backup wall in a brick veneer wall assembly.
CMU Backup Wall: Pros: Strength and Durability: CMU backup walls are known for their strength and durability. They can withstand heavy loads and provide a robust support structure for the brick veneer. Fire Resistance: CMU has excellent fire-resistant properties, which enhances the overall fire safety of the wall assembly. Sound Insulation: CMU backup walls offer good sound insulation properties, reducing the transmission of noise between interior and exterior spaces. Thermal Mass: CMU has high thermal mass, meaning it can store heat and help regulate temperature fluctuations. This can contribute to improved energy efficiency and reduced heating/cooling costs. Cons: Higher Cost: CMU materials and installation can be more expensive compared to steel stud backup walls, primarily due to the cost of materials and labor. Heavyweight: CMU walls are heavy, which can pose challenges during construction, transportation, and foundation design. Additional structural considerations may be required to support the weight of the wall. Limited Design Flexibility: CMU walls offer limited design flexibility compared to steel stud walls. They may not be as easily modified or adapted to accommodate design changes during construction. Steel Stud Backup Wall: Pros: Lightweight Construction: Steel stud backup walls are lightweight, making them easier to handle and transport. They impose less load on the building structure, simplifying foundation design. Ability to deflect lateral load before the bending stress in them exceeds their ultimate capacity. This is obtainable by increasing the stiffness. However this increases the cost of the project. Design Flexibility: Steel stud walls offer greater design flexibility, allowing for easier modifications and adaptations during construction. They can accommodate curved walls, irregular shapes, and various architectural features. Cost-Effective: Steel stud walls are generally more cost-effective compared to CMU walls due to the lower material costs and faster installation. They require less labor and may result in reduced construction time. Good Insulation: Steel stud walls can incorporate insulation materials easily, resulting in improved energy efficiency and thermal performance. 1-2 Story Buildings have continuous steel stud from the top to bottom and do not require shelf angles. Only requiring a slip connection to connect the structural frame to the floor or roof. Cons: Lower Strength: Steel stud walls may not possess the same structural strength as CMU walls. They may require additional bracing or reinforcing to withstand heavy loads or high wind pressures. Fire Resistance: Steel studs are not inherently fire-resistant and may require additional fireproofing measures to meet building codes and regulations. Sound Transmission: Steel stud walls can have higher sound transmission compared to CMU walls. Additional sound insulation measures may be needed to achieve desired acoustic performance. Corrosion of the CFS anchors over time by condensation. Requires an Air-Weather barrier.
Discuss the difference between control joints and expansion joints in a stucco-clad wall.
Expansion Joints: - Used to respond to large movements in the building structure - Installed at regular intervals Control: - Create weak points in the stucco for controlled cracking. To adapt to the shrinkage of stucco. - Installed at corners, changes in wall height, etc.
Using a sketch, explain the anatomy of stucco applied over a metal-stud wall assembly, showing all components.
Gypsum, CFS Stud/Insulation, Fiberglass-Mat-Faced-Gypsum, Self Adhering Joint Tape, Air-Weather Barrier, Water Resistant Membrane, Lath, Scratch Coat (3/8"), Brown Coat (3/8"), Finish Coat (1/8")
With the help of sketches and notes, explain various ways in which weep holes can be provided in a brick veneer assembly.
Open Head Joints: Head Joints are left open to allow water to drain. The open-head joints should be spaced at regular intervals along the wall, typically every few courses. Joint Screen: An L-shaped sheet metal or plastic element. Its vertical leg has louvered openings to let the water out, and the horizontal leg is embedded in the horizontal mortar joint of the veneer. The joint screen has the same width as the head joints. (Honeycomb is only available) Wicks: Cotton Rope inserted in the mortar head joint that absorbs water from the air space by capillary action and drains it to the outside. Their drainage efficiency is low. Weep Tubes: Small plastic or metal tubes inserted into the mortar joints at the bottom of the brick veneer assembly. They extend through the mortar joint, allowing water to drain out.
Explain the difference between PB EIFS and PM EIFS. Which of the two methods is more commonly used?
PB: - Polymer Based - Soft Coat - Strong and Flexible - PB is more commonly used PM: - Polymer-Modified - Hard Coat - Thicker, Harder Coating
Discuss the pros and cons of EIFS cladding compared with stucco cladding.
Pros of EIFS Cladding: - Energy Efficiency: EIFS provides excellent thermal insulation - Versatile Design Options: Wide range of colors, textures, and finishes - Lightweight: Reduces structural load Cons of EIFS Cladding: - Vulnerability to Moisture Intrusion: Improper installation or lack of maintenance can lead to moisture problems, such as water penetration and trapped moisture within the EIFS system which can lead to mold (No Breathability) - Poor Impact Resistance - Complex Installation: Requires skilled installation to ensure proper integration with other building components, proper flashing, and effective sealing to prevent water intrusion. Pros of Stucco Cladding: - Durability - Fire Resistance - Minimal Maintenance Cons of Stucco Cladding: - Lack of Insulation - Limited Design Options - Prone to Natural Cracking: Due to the natural drying and curing process, as well as movement caused by temperature fluctuations. (Hairline Cracks) - Heavy Weight: Potentially requiring additional structural considerations and higher construction costs.
Using sketches and notes, explain the functions of a shelf angle and a lintel angle in a brick veneer assembly.
Shelf Angle: A shelf angle is a structural component used to support the weight of horizontal surfaces such as shelves, ledges, or balconies. Lintel Angle: A lintel angle is a structural element used to support the load of a wall or opening above it, such as doors, windows, or openings in masonry walls.
What are the essential differences between stucco applied on a stud wall and that applied on a CMU wall?
Stucco Applied on a Stud Wall: - Total stucco thickness is ≈7/8" - Not a barrier wall - Able to drain rainwater through drainage plain - Sheathing provides a flat surface for the stucco application. - Requires a scratch coat (Acts as a bonding agent between the stucco and the sheathing) - Requires a lath over the scratch coat (Provides a keying surface for the stucco, allowing it to adhere properly to the wall) - Control joints have a maximum area of 144 feet² - 18 ft maximum length between control joints - Length-to-width ratio of 1 and 2.5 Stucco Applied on a CMU Wall: - Total stucco thickness is 5/8" to 3/4" - Acts as a barrier wall meaning there is no way for rainwater to drain if it were to penetrate. - Rigidity provides better structural integrity to the stucco - Textured surface that helps with the adhesion of the stucco. - Control joints have a maximum area of 250 feet²
With the help of a sketch, explain the two-stage joint seal in precast concrete wall panels. What are its advantages over a single-stage joint seal?
Two-Stage Joint Seal - Two joints -Outer seal provides a weather barrier and contains weep holes. - Inner seal is continuous, without any openings, and is meant to provide an air barrier. - The provision of the air barrier and the openings in the exterior seal make the two-stage joint system function as a rain screen Advantages of Two-Stage Joint Seal over Single-Stage Joint Seal: - Enhanced Durability - Improved Weather Resistance - Reduced Maintenance
