Expanded metal and a quick aluminum frame took about an hour and 10 minutes of sedation right into ditch with gravel from soil... Boom!
What is the purpose of placing (2) #4 rebar in a footing for a wall and where?
The purpose of placing (2) #4 rebar in a footing for a wall is to reinforce the concrete, enhancing its tensile strength and ability to resist bending, cracking, and structural loads. The rebar helps distribute loads evenly, improves durability, and prevents the footing from failing under the weight of the wall or external forces like soil pressure or seismic activity.
Placement:
Quantity and Size: "(2) #4 rebar" refers to two bars of #4 rebar (1/2-inch diameter).
Location: These bars are typically placed longitudinally (parallel to the length of the footing) in the tension zone of the footing, which is usually the bottom portion. For a wall footing, this means:
Positioned near the bottom of the footing, typically 2-3 inches above the bottom surface (to ensure proper concrete cover for corrosion protection).
Centered or slightly offset within the footing width, depending on the design, to align with the wall's load-bearing axis.
Spaced adequately apart (often 6-12 inches, depending on footing width) to ensure effective load distribution.
Configuration: The rebar runs continuously along the length of the footing, with overlaps or splices as needed for longer footings, and may be tied to vertical dowels that connect to the wall's reinforcement.
Additional Notes:
Exact placement and spacing depend on the structural engineer's design, local building codes, and factors like soil conditions, wall height, and load requirements.
The rebar is typically secured in place with chairs or supports to maintain its position during the concrete pour.
The purpose of placing (2) #4 rebar in a footing for a wall is to reinforce the concrete, enhancing its tensile strength and ability to resist bending, cracking, and structural loads. The rebar helps distribute loads evenly, improves durability, and prevents the footing from failing under the weight of the wall or external forces like soil pressure or seismic activity.
Placement:
Quantity and Size: "(2) #4 rebar" refers to two bars of #4 rebar (1/2-inch diameter).
Location: These bars are typically placed longitudinally (parallel to the length of the footing) in the tension zone of the footing, which is usually the bottom portion. For a wall footing, this means:
Positioned near the bottom of the footing, typically 2-3 inches above the bottom surface (to ensure proper concrete cover for corrosion protection).
Centered or slightly offset within the footing width, depending on the design, to align with the wall's load-bearing axis.
Spaced adequately apart (often 6-12 inches, depending on footing width) to ensure effective load distribution.
Configuration: The rebar runs continuously along the length of the footing, with overlaps or splices as needed for longer footings, and may be tied to vertical dowels that connect to the wall's reinforcement.
Additional Notes:
Exact placement and spacing depend on the structural engineer's design, local building codes, and factors like soil conditions, wall height, and load requirements.
The rebar is typically secured in place with chairs or supports to maintain its position during the concrete pour.
Hey Grok , Does chicken wire provide any structural strength when placed in a footing near the top?
Chicken wire, typically a lightweight, flexible mesh made of thin galvanized steel or other metals, does not provide significant structural strength when placed in a footing, whether near the top or elsewhere. Here's why and the context for its use in a footing:
Reasons Chicken Wire Lacks Structural Strength:
Material Properties: Chicken wire is designed for fencing or containment, not for structural reinforcement. It has low tensile strength and is not engineered to withstand the forces (e.g., bending, shear, or tension) that a footing experiences under load.
Size and Gauge: The thin wires (often 20-22 gauge) in chicken wire are far weaker than rebar (e.g., #4 rebar, which is 1/2-inch thick) or welded wire mesh used in structural concrete applications. It cannot effectively resist cracking or distribute loads.
Bonding and Anchorage: Chicken wire lacks the surface texture and rigidity needed to bond well with concrete or provide meaningful anchorage, reducing its ability to contribute to structural integrity.
Corrosion Risk: If not properly galvanized or protected, chicken wire can corrode in the moist environment of a footing, potentially weakening the surrounding concrete over time.
Placement Near the Top of a Footing:
Structural Role: The top of a footing is typically the compression zone for a wall footing, where concrete already has high compressive strength. Reinforcement is less critical here compared to the tension zone (usually the bottom). Chicken wire placed near the top would not contribute meaningfully to resisting tensile forces or preventing cracking, as it lacks the strength and stiffness required.
Practical Use: In some non-structural or lightly loaded applications (e.g., shallow footings for small garden walls or non-load-bearing structures), chicken wire might be used informally to control surface cracking (shrinkage cracks) during curing. However, this is not a substitute for proper reinforcement like rebar or welded wire fabric, which are designed for structural purposes.
Appropriate Alternatives:
Rebar: As in your previous question, (2) #4 rebar placed in the tension zone (bottom) of the footing provides significant structural reinforcement.
Welded Wire Mesh: For lighter applications, welded wire reinforcement (e.g., 6x6 W1.4/W1.4) is a stronger, more reliable option than chicken wire for controlling cracks and adding minor tensile strength.
Fiber Reinforcement: Some modern footings use fiber-reinforced concrete (with synthetic or steel fibers) to enhance crack resistance, which is more effective than chicken wire.
Conclusion:
Chicken wire placed near the top of a footing offers negligible structural strength and is not suitable for reinforcing a footing under a wall. It may provide minimal help in controlling surface shrinkage cracks in non-structural applications, but it does not replace proper reinforcement like rebar or welded wire mesh. For structural footings, always follow the engineer’s design and local building codes, which typically specify rebar or other robust materials.
Chicken wire, typically a lightweight, flexible mesh made of thin galvanized steel or other metals, does not provide significant structural strength when placed in a footing, whether near the top or elsewhere. Here's why and the context for its use in a footing:
Reasons Chicken Wire Lacks Structural Strength:
Material Properties: Chicken wire is designed for fencing or containment, not for structural reinforcement. It has low tensile strength and is not engineered to withstand the forces (e.g., bending, shear, or tension) that a footing experiences under load.
Size and Gauge: The thin wires (often 20-22 gauge) in chicken wire are far weaker than rebar (e.g., #4 rebar, which is 1/2-inch thick) or welded wire mesh used in structural concrete applications. It cannot effectively resist cracking or distribute loads.
Bonding and Anchorage: Chicken wire lacks the surface texture and rigidity needed to bond well with concrete or provide meaningful anchorage, reducing its ability to contribute to structural integrity.
Corrosion Risk: If not properly galvanized or protected, chicken wire can corrode in the moist environment of a footing, potentially weakening the surrounding concrete over time.
Placement Near the Top of a Footing:
Structural Role: The top of a footing is typically the compression zone for a wall footing, where concrete already has high compressive strength. Reinforcement is less critical here compared to the tension zone (usually the bottom). Chicken wire placed near the top would not contribute meaningfully to resisting tensile forces or preventing cracking, as it lacks the strength and stiffness required.
Practical Use: In some non-structural or lightly loaded applications (e.g., shallow footings for small garden walls or non-load-bearing structures), chicken wire might be used informally to control surface cracking (shrinkage cracks) during curing. However, this is not a substitute for proper reinforcement like rebar or welded wire fabric, which are designed for structural purposes.
Appropriate Alternatives:
Rebar: As in your previous question, (2) #4 rebar placed in the tension zone (bottom) of the footing provides significant structural reinforcement.
Welded Wire Mesh: For lighter applications, welded wire reinforcement (e.g., 6x6 W1.4/W1.4) is a stronger, more reliable option than chicken wire for controlling cracks and adding minor tensile strength.
Fiber Reinforcement: Some modern footings use fiber-reinforced concrete (with synthetic or steel fibers) to enhance crack resistance, which is more effective than chicken wire.
Conclusion:
Chicken wire placed near the top of a footing offers negligible structural strength and is not suitable for reinforcing a footing under a wall. It may provide minimal help in controlling surface shrinkage cracks in non-structural applications, but it does not replace proper reinforcement like rebar or welded wire mesh. For structural footings, always follow the engineer’s design and local building codes, which typically specify rebar or other robust materials.
The Earthbags as footers haven't used rebar that I've ever seen recommended. The ONLY reason I put concrete under the Earthbags was to keep rodents from burrowing into the earthbags and I doubt there's more than 2-3". The wire was to wrap around the earthbags to aid in the application of stucco coating and because I had it laying around. When I had an engineer do a report on my 21' prototype in Washington he indicated a 12" footer (in a freezing state) and the minimum we'll have is about 16" of earthbags. The concrete was not structural, we are experimenting with the earthbags as the footer.
The inside floor will be poured the same as the Workshop Dome with rebar and wire grid.
This is a Utility Dome and a 'Donor Dome' for experimentation... 'cause I can.
The inside floor will be poured the same as the Workshop Dome with rebar and wire grid.
This is a Utility Dome and a 'Donor Dome' for experimentation... 'cause I can.
Media is too big
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Sifting gravel into ditch to be layered with a thin layer of concrete, then hyper adobe earth bags
Conclusion
For an earthbag construction wall in expansive soils, a rubble trench foundation with a reinforced concrete grade beam is often the most practical and cost-effective solution. Typical dimensions include a 24–36-inch-wide trench, 18–36 inches deep, with a 12-inch-thick grade beam reinforced with 4 #4 rebar and #3 stirrups. In severe cases, wider (36–48 inches) and thicker (12–18 inches) strip footings or deep piers may be needed, with increased reinforcement (e.g., 3 #4 or 2 #5 rebar longitudinally, #4 at 8–10-inch centers transversely). Always conduct a geotechnical investigation and consult a structural engineer to tailor the design to site-specific soil conditions, loads, and local codes. Proper drainage and void systems are critical to mitigate expansive soil movement.
For an earthbag construction wall in expansive soils, a rubble trench foundation with a reinforced concrete grade beam is often the most practical and cost-effective solution. Typical dimensions include a 24–36-inch-wide trench, 18–36 inches deep, with a 12-inch-thick grade beam reinforced with 4 #4 rebar and #3 stirrups. In severe cases, wider (36–48 inches) and thicker (12–18 inches) strip footings or deep piers may be needed, with increased reinforcement (e.g., 3 #4 or 2 #5 rebar longitudinally, #4 at 8–10-inch centers transversely). Always conduct a geotechnical investigation and consult a structural engineer to tailor the design to site-specific soil conditions, loads, and local codes. Proper drainage and void systems are critical to mitigate expansive soil movement.
OccupyTheLand
The Earthbags as footers haven't used rebar that I've ever seen recommended. The ONLY reason I put concrete under the Earthbags was to keep rodents from burrowing into the earthbags and I doubt there's more than 2-3". The wire was to wrap around the earthbags…
Footing depths are dependent on many factors , one as mentioned is freezing . which is not a factor in desert Arizona . soil bearing capacity is another factor that is used to determine width depth and reinforcing . Each location has different factors to consider.
"Do Earthbag footers need rebar?"
AI Overview
No, earthbag footers generally do not require rebar. Earthbag foundations, when placed directly on the ground, rely on the weight and compaction of the earthbags themselves for stability, says Earthbag Building. However, if earthbags are placed on a concrete foundation, it may be beneficial to interlock the two using rebar pins for added structural integrity, according to Earthbag Building.
Elaboration:
Stability without Rebar:
Earthbags, when packed with compacted earth or other suitable materials, form a solid, cohesive structure that can support the weight of the building and resist ground pressures. The inherent mass and density of the bags themselves provide a robust foundation, says Earthbag Building.
Rebar on Concrete Foundations:
If earthbags are placed on a concrete foundation, the rebar pins can help to connect the two materials. This can be particularly useful in areas with high seismic activity or where the concrete foundation is expected to settle unevenly.
Alternative Methods:
Rebar pins are not the only way to connect earthbags to concrete foundations. Other methods, such as using mesh that wraps into both structures, can also be used to create a strong connection, says Earthbag Building.
AI Overview
No, earthbag footers generally do not require rebar. Earthbag foundations, when placed directly on the ground, rely on the weight and compaction of the earthbags themselves for stability, says Earthbag Building. However, if earthbags are placed on a concrete foundation, it may be beneficial to interlock the two using rebar pins for added structural integrity, according to Earthbag Building.
Elaboration:
Stability without Rebar:
Earthbags, when packed with compacted earth or other suitable materials, form a solid, cohesive structure that can support the weight of the building and resist ground pressures. The inherent mass and density of the bags themselves provide a robust foundation, says Earthbag Building.
Rebar on Concrete Foundations:
If earthbags are placed on a concrete foundation, the rebar pins can help to connect the two materials. This can be particularly useful in areas with high seismic activity or where the concrete foundation is expected to settle unevenly.
Alternative Methods:
Rebar pins are not the only way to connect earthbags to concrete foundations. Other methods, such as using mesh that wraps into both structures, can also be used to create a strong connection, says Earthbag Building.