14.3 Wall Schedules, Retaining Wall Sections & Penetration Details
Key Takeaways
For walls thicker than 10 inches, ACI 318-19 Section 11.7.2.3 generally requires at least two layers of distributed reinforcement in each direction. It excepts single-story basement walls and cantilever retaining walls.
Read the wall mark, story, face, curtain count and bar layering from the approved schedule and section.
Use the retaining wall section to identify the stem, heel, toe, dowels, joints and specified load-resisting reinforcement.
Match the boundary element mark to its detail and verify the specified vertical bars and transverse confinement.
Verify opening trim and any diagonal bars from the approved detail. Refer unshown penetrations for design review.
14.3 Wall Schedules, Retaining Wall Sections & Penetration Details
Read the wall mark and story together. Compare the schedule’s thickness, reinforcement and curtain count to the section. Then locate any boundary elements, retaining footing or opening details that apply to the wall.
Structural Concrete Wall Schedules & Curtain Architecture
Structural drawings identify cast-in-place concrete walls using wall marks such as W1, W2, BW-1 (basement wall), or SW-1 (shear wall). The Wall Schedule specifies rebar arrangements across stories.
Sample Structural Wall Schedule
| Wall Mark | Story Level | Thickness () | Vertical Rebar | Horizontal Rebar | Curtains | Boundary Element / Details |
|---|---|---|---|---|---|---|
| W1 | Level 1 to Level 2 | 8" | #4 @ 12" O.C. | #4 @ 12" O.C. | Single (Center) | Standard corner trim bars |
| W2 | Basement to Level 1 | 12" | #5 @ 10" O.C. | #4 @ 12" O.C. | Double (Each Face) | Vert bars outside on earth face |
| SW-1 | Footing to Level 1 | 14" | #6 @ 8" O.C. | #5 @ 8" O.C. | Double (Each Face) | SBE-1 at ends (see detail 4/S4) |
| SW-1 | Level 1 to Level 2 | 12" | #5 @ 10" O.C. | #4 @ 10" O.C. | Double (Each Face) | SBE-2 at ends (see detail 5/S4) |
| BW-1 | Foundation to Grade | 16" | #7 @ 8" (EF), #5 @ 12" (IF) | #5 @ 10" O.C. | Double (Each Face) | Earth face tension steel; Keyway |
Single Curtain vs. Double Curtain Code Rules
ACI 318-19 Section 11.7.2.3 requires at least two layers of distributed reinforcement in each direction for walls thicker than 10 inches, except single-story basement walls and cantilever retaining walls. Each layer lies near a face. The exceptions do not preclude a design with two layers. For special structural walls, Section 18.10.2.2 requires at least two curtains when or the ratio of overall wall height to length is at least 2.0. Check the approved wall type and applicable detailing requirements.
Read the order of vertical and horizontal bars from the section. If the sample W2 detail places the vertical bars closest to the earth face, verify that order at W2. The required layer order can change with the wall’s load direction, cover and connections. Use the approved spacing for each direction and face. ACI 318-19 Section 11.7 sets separate limits for cast-in-place and precast walls and additional limits where in-plane shear reinforcement is required.
Special Boundary Elements (SBE) in Shear Walls
In tall concrete buildings subjected to wind and seismic lateral loads, structural shear walls behave as giant cantilevers. Bending moments induce tremendous compressive and tensile stresses at the extreme edges (flanges) of the wall.
+-------------------------------------------------------------+
| [SBE-1] [SBE-1] |
| +-------+ Wall Web +-------+ |
| | o o o | ======================================= | o o o | |
| | o o o | Double Curtain Reinforcement | o o o | |
| +-------+ +-------+ |
| Boundary Boundary |
+-------------------------------------------------------------+
The boundary element detail identifies the confinement zone, longitudinal bars and transverse reinforcement, including hook configurations and the extent of confinement. For the sample SW-1 at the footing-to-Level-1 tier, verify the layout in SBE-1. Above Level 1 the schedule refers to a different detail. Read the drawings for the reinforcement connection to the footing or mat and where the confinement changes. Chapter 18 provides the special structural wall requirements.
Retaining Wall Sections & Detail Interpretation
Cantilever retaining walls resist lateral earth pressure through cantilever action of the vertical stem wall fixed into a reinforced concrete spread footing.
Exposed face Backfill face
| |
| | | ← Vertical stem bars
| | | near backfill face
--------------------+-------------|--+---------------------
| | ===== Heel bars |
| Toe bars ===== | |
+---------------------------------------------------------+
Toe projects outward Heel below backfill
In the illustrated cantilever wall under lateral backfill pressure, the stem bends away from the soil. The earth side is the tension face for that load case. Match the earth and exposed faces on the actual section, and verify the primary bars and layer order. If the approved detail identifies separate reinforcement at the footing heel and toe, compare the top and bottom bar placements to that detail. The heel projects beneath the retained soil, and the toe projects on the opposite side. Confirm the dowel sizes, embedments and laps. Check a specified key or joint preparation separately from any drainage details. Use the project design for the actual support and loading conditions.
Wall Penetrations, Openings & Reentrant Corner Reinforcement
Wall openings can interrupt the load path and concentrate stress at the corners. This example shows a detail for one opening with jamb, header, sill and diagonal bars.
Header Trimmer Bars (Top)
================================
|| / \ ||
Jamb || / (2) #5 Diag \ || Jamb
Trimmer || / \ || Trimmer
Bars (Left) || +----------------------+ || Bars (Right)
|| | | ||
|| | WALL OPENING | ||
|| | | ||
|| +----------------------+ ||
|| \ / ||
|| \ (2) #5 Diag / ||
|| \ / ||
================================
Sill Trimmer Bars (Bottom)
Opening trim and design review
A rectangular opening interrupts the reinforcement layout and can concentrate stresses at its corners. ACI 318-19 Section 11.7.5.1 requires additional reinforcement around windows, doors and similarly sized openings. It requires at least two No. 5 bars for walls with two layers in both directions and one No. 5 bar for walls with a single layer in both directions. Anchor the bars to develop the specified yield strength in tension at the corners. Check the approved jamb, header and sill details, including any diagonal bars and their orientation, location and anchorage. The figure illustrates one possible project detail.
For a proposed opening missing from the approved construction documents, record the location and geometry and refer it for design review. ACI 318-19 Section 26.8.2 requires review of unshown embedments and installation of piping and conduit without cutting, bending or displacing specified reinforcement. Check the actual approved spacing for a pipe cluster. Changes to approved documents go through the applicable approval process.
| Inspection task | What to check |
|---|---|
| Wall and curtains | Wall mark and story, thickness, count, bar size and spacing at each face. |
| Retaining section | Tension face for the stated detail, heel and toe reinforcement, and dowel laps. |
| Boundary element | Approved confinement length, bar sizes, spacing and hook details. |
| Opening | Location, size, trim layout and anchorage shown on the approved detail. |
A cast-in-place structural wall is neither a single-story basement wall nor a cantilever retaining wall. Under ACI 318-19 Section 11.7.2.3, what thickness triggers at least two layers of distributed reinforcement in each direction?
More than 6 inches.
More than 8 inches.
More than 12 inches.
More than 10 inches.
The section shows a retaining stem fixed at the base and subject to lateral pressure from the backfill. Which stem face is in tension near the base for this load case?
Both faces equally.
The earth-retaining face.
The exposed front face.
The footing shear key.
The approved opening detail calls for jamb and header bars plus two diagonal No. 5 bars at each corner. The jamb and header bars are in place, but the corner bars are missing. What is the inspection finding?
The opening conforms because jamb and header bars replace all corner bars.
The opening conforms if a sleeve is installed after the wall is cast.
The opening does not conform. Document the missing bars and notify the contractor.
The inspector should add diagonal bars of any available size.
Sections you finish are checked off in the contents.