Understanding Footing Reinforcement
Proper rebar calculations ensure structural integrity and code compliance for concrete footings.
- Rebar Requirements Minimum: 2 #4 bars. Typical: #5-#7 bars. Spacing: d/3 or 18" max. Cover: 3" bottom/sides. Lap splice: 40× diameter. Corner bars: 24" extension.
- Design Loads Dead load: structure weight. Live load: occupancy. Soil pressure: 1500-3000 psf. Factor of safety: 2.0. Minimum depth: below frost line.
- Size Guidelines Width: 2× wall width min. Depth: L/6 minimum. Thickness: 8" minimum. Projection: 6" min each side. Keyway: 2×4" where required.
- Code Requirements ACI 318 Chapter 15. IBC Section 1809. Minimum steel: 0.0018bh. Temperature steel: #4 at 18" O.C. Dowels: match vertical bars.
Construction Guide
Installation Details
Chairs: 4' O.C. Tie wire: 16 gauge black. Clean steel: no rust scale. Secure bars: prevent movement. Inspection: pre-pour required.
Special Conditions
Grade beams: additional steel. Pile caps: mat reinforcing. Frost walls: vertical bars. Stepped footings: continuous steel. Heavy loads: two-way steel.
Cost Analysis
Steel: $1.25-1.75/lb installed. Chairs: $0.50 each. Ties: $0.25 each. Labor: $1.00/ft² of footing. Minimum charge: $500. Inspection: $150.
Quality Control
Bar grade: 60 ksi min. Mill certs required. Bend radius: 6× diameter. Support: no ground contact. Splices: staggered 5'. Clearance: ±1/4".
Footing Basics
Understanding footing types and requirements.
- Continuous Wall support.
- Isolated Column support.
- Spread Load distribution.
- Strip Linear support.
Rebar Sizes
#3
3/8" diameter.
#4
1/2" diameter.
#5
5/8" diameter.
#6
3/4" diameter.
Installation Tips
- Coverage Proper depth.
- Spacing Even distribution.
- Overlap Proper splicing.
- Support Chairs/spacers.
Code Requirements
- Coverage Minimum depth.
- Spacing Maximum gaps.
- Strength Load capacity.
- Inspection Verification.