+---
+title: Shallow Foundations (Spread and Strip Footings)
+category: Structural / Concrete
+toc_depth: 3
+description: >
+ When to use: Buildings, structures, and site improvements that bear directly on
+ competent soil or rock within a few feet of finish grade. Covers the execution and
+ quality assurance of spread (isolated column) footings, continuous wall (strip)
+ footings, combined footings, and strap (cantilever) footings — forming, bearing-surface
+ preparation, reinforcement and dowel layout, anchor-bolt and embedded-plate setting,
+ keyways and construction joints, lean-concrete sub-bases, and bearing-inspection hold
+ points. Applies to commercial, institutional, industrial, and multi-family residential work.
+ Not intended for: Deep foundations — piles, drilled shafts, micropiles, helical piles
+ (use sync/deep-foundations); slabs-on-grade and thickened slab edges (use sync/slab-on-grade);
+ concrete materials, mix design, placement, and curing (use sync/cast-in-place-concrete);
+ reinforcing-bar material, fabrication, and splicing (use sync/concrete-reinforcement);
+ foundation-wall waterproofing and drainage (use sync/below-grade-waterproofing);
+ excavation, dewatering, and engineered fill (use sync/earthwork); precast grade beams
+ (use sync/precast-concrete); tilt-up panel footing ledges (use sync/tilt-up-concrete);
+ and permanent retaining walls (use sync/retaining-walls).
+---
+
+# Scope {toc}
+
+## This standard specifies the execution and quality assurance of shallow foundations — spread footings, continuous wall footings, combined footings, and strap footings — that bear directly on soil or rock within a few feet of finish grade.
+
+## This standard governs forming, bearing-surface preparation, lean-concrete sub-bases, reinforcement and dowel layout, anchor-bolt and embedded-plate setting, keyways and construction joints, bearing inspection, and acceptance of shallow foundation work.
+
+## This standard is an execution specification, not a structural design document; the footing schedule prepared by the Engineer of Record and the project geotechnical report govern all dimensions, reinforcement, bearing pressures, and elevations. {note}
+
+## The contractor builds what the drawings and schedule require; this standard tells the contractor how to execute and verify that work to a defensible quality. Where a value here conflicts with the footing schedule or geotechnical report, those engineering deliverables govern. {note}
+
+## Concrete materials, mix proportioning, admixtures, conveying, placing, consolidation, finishing, curing, and cylinder testing are specified once for all cast-in-place work in [[sync/cast-in-place-concrete]] and are incorporated here by reference rather than restated. {note}
+
+## Footings are cast-in-place concrete. To avoid two divergent sources of truth, this standard references the concrete-execution standard for everything common to all CIP work and confines itself to what is unique to footings: bearing verification, geometry and forming, embed setting, and the link between the geotechnical report and the field. {note}
+
+## Reinforcing-bar material, fabrication, bending, splicing, and placement tolerances are specified in [[sync/concrete-reinforcement]]; this standard specifies only footing-specific bar layout, cover, and dowel embedment. {note}
+
+## Deep foundation elements — driven piles, drilled shafts, continuous-flight-auger piles, micropiles, and helical piles — are outside this standard and are covered by [[sync/deep-foundations]]. {note}
+
+## Slabs-on-grade, including thickened slab edges that function as integral grade beams, are covered by [[sync/slab-on-grade]] and are not within this standard. {note}
+
+## Excavation, dewatering, subgrade proof-rolling, and placement and compaction of engineered fill beneath footings are covered by [[sync/earthwork]]; this standard begins at the prepared, accepted bearing surface. {note}
+
+## Below-grade waterproofing membranes and foundation drainage are covered by [[sync/below-grade-waterproofing]]; precast grade beams by [[sync/precast-concrete]]; tilt-up panel footing ledges by [[sync/tilt-up-concrete]]; and permanent earth-retaining structures by [[sync/retaining-walls]]. {note}
+
+# Referenced Standards {toc}
+
+## Materials, design, and execution shall comply with the latest adopted edition of each of the following unless a specific edition is cited or a more recent edition is mandated by the authority having jurisdiction.
+
+## Where referenced standards conflict, the more stringent requirement shall govern unless the Engineer of Record directs otherwise in writing.
+
+| Standard | Title |
+|----------|-------|
+| ACI CODE-318-25 | Building Code Requirements for Structural Concrete and Commentary |
+| ACI 301-20 | Specifications for Concrete Construction |
+| ACI 117-10 (R2015) | Specification for Tolerances for Concrete Construction and Materials |
+| ACI 336.2R-88 (R2002) | Suggested Analysis and Design Procedures for Combined Footings and Mats |
+| IBC 2021 (Section 1808) | International Building Code — Foundation and Soil Investigations |
+| IBC 2021 (Section 1809) | International Building Code — Shallow Foundations |
+| ASCE/SEI 7-22 | Minimum Design Loads and Associated Criteria for Buildings and Other Structures |
+| ASTM A615/A615M | Deformed and Plain Carbon-Steel Bars for Concrete Reinforcement |
+| ASTM A706/A706M | Deformed and Plain Low-Alloy Steel Bars for Concrete Reinforcement |
+| ASTM C150/C150M | Portland Cement |
+| ASTM C94/C94M | Ready-Mixed Concrete |
+| ASTM C39/C39M | Compressive Strength of Cylindrical Concrete Specimens |
+| ASTM D1557 | Laboratory Compaction Characteristics of Soil Using Modified Effort |
+| ASTM D1586/D1586M | Standard Penetration Test (SPT) and Split-Barrel Sampling of Soils |
+
+# Submittals {toc}
+
+## Action submittals are documents the Engineer of Record reviews and must accept before the related work proceeds; they establish that the contractor's intended means comply with the drawings before any concrete is placed. {note}
+
+### The Contractor shall submit the following action submittals for review and acceptance before placing footing concrete:
+- Concrete mix designs for each specified compressive strength, with the geotechnical sulfate-exposure class addressed.
+- Reinforcement placing drawings showing bar size, spacing, cover, dowel layout, and lap/development lengths for each footing type.
+- Anchor-bolt and embedded-plate setting drawings, including template details and the steel fabricator's bolt-pattern coordination.
+- Footing layout and excavation plan keyed to the footing schedule, identifying each bearing elevation and any stepped-footing transitions.
+- Proposed lean-concrete (mud-mat) sub-base locations and thickness where used.
+
+```datasheet
+label: Action Submittals
+type: checkbox
+options:
+ - Concrete mix designs (per specified strength)
+ - Reinforcement placing drawings
+ - Anchor-bolt / embedded-plate setting drawings
+ - Footing layout and excavation plan
+ - Lean-concrete sub-base plan
+default:
+ - Concrete mix designs (per specified strength)
+ - Reinforcement placing drawings
+ - Anchor-bolt / embedded-plate setting drawings
+ - Footing layout and excavation plan
+```
+
+## Informational submittals document conditions and qualifications; the Engineer reviews them for record and to confirm field readiness, but they do not by themselves authorize work. {note}
+
+### The Contractor shall submit the following informational submittals:
+- Geotechnical report excerpts establishing the allowable bearing pressure and bearing stratum for each footing area.
+- Qualifications of the special inspection and testing agency performing bearing and concrete inspection.
+- Bearing-surface inspection reports for each footing, signed by the geotechnical engineer of record or their authorized representative.
+- Aggregate-base and engineered-fill compaction test reports beneath footings, referencing [[sync/earthwork]].
+
+```datasheet
+label: Informational Submittals
+type: checkbox
+options:
+ - Geotechnical report excerpts (bearing pressure / stratum)
+ - Testing agency qualifications
+ - Bearing-surface inspection reports
+ - Subgrade / fill compaction test reports
+default:
+ - Geotechnical report excerpts (bearing pressure / stratum)
+ - Bearing-surface inspection reports
+ - Subgrade / fill compaction test reports
+```
+
+## Closeout submittals are the record set delivered at completion so the Owner can document what was actually built and verify acceptance. {note}
+
+### The Contractor shall submit the following closeout submittals before final acceptance of foundation work:
+- Concrete cylinder break reports (7-day and 28-day) for all footing placements.
+- As-built footing elevations and anchor-bolt locations where they deviate from the schedule within tolerance.
+- Signed bearing-inspection and pre-pour inspection records for all footings.
+
+```datasheet
+label: Closeout Submittals
+type: checkbox
+options:
+ - Cylinder break reports (7-day and 28-day)
+ - As-built footing / anchor-bolt locations
+ - Signed bearing and pre-pour inspection records
+default:
+ - Cylinder break reports (7-day and 28-day)
+ - Signed bearing and pre-pour inspection records
+```
+
+# Quality Assurance {toc}
+
+## The bearing-inspection hold point is the single highest-value quality control step for shallow foundations: once concrete is placed, the bearing condition can no longer be verified, so it must be confirmed and signed off before any concrete or reinforcement covers the bearing surface. {note}
+
+## A footing sized for an assumed bearing pressure is only as good as the soil it actually rests on. Variable fill, soft pockets, organic seams, perched water, and over-excavation all defeat the design assumption. The pre-pour bearing inspection catches these before they are buried. {note}
+
+## The bearing surface of every footing shall be inspected and accepted in writing by the geotechnical engineer of record or their authorized representative before reinforcement is set or concrete is placed.
+
+## The contractor shall not place lean concrete, reinforcement, or footing concrete on any bearing surface until the bearing inspection sign-off for that footing has been obtained.
+
+## Where the inspected bearing condition does not match the allowable bearing pressure assumed on the footing schedule, the contractor shall stop work on that footing and obtain written direction from the Engineer of Record before proceeding.
+
+## A pre-pour inspection shall verify footing dimensions, bearing elevation, reinforcement size and spacing, cover, dowel layout, anchor-bolt template, and form condition.
+
+## The pre-pour inspection shall be documented for each footing or footing group.
+
+## Special inspection of shallow foundations shall be performed by a qualified agency in accordance with IBC 2021 Chapter 17 and the project statement of special inspections.
+
+## The testing agency shall sample and test footing concrete in accordance with [[sync/cast-in-place-concrete]]; at minimum, one set of cylinders shall be taken per 50 CY of concrete placed or per day of placement, whichever yields more sets.
+
+## Concrete represented by any cylinder set whose 28-day average compressive strength falls below the specified f'c shall be evaluated in accordance with ACI 318-25, and the Engineer of Record shall determine acceptance, additional testing, or remediation.
+
+## Mock-ups and pre-construction conferences are coordination tools, not contractual obligations on the foundation subcontractor; they are most useful where anchor-bolt patterns are complex or where stepped footings on a sloped site introduce sequencing risk. {note}
+
+# Geotechnical Basis and Bearing {toc}
+
+## The allowable bearing pressure governs the plan dimensions of every footing; it is established by the geotechnical engineer from the soil investigation. {note}
+
+## The allowable bearing pressure shall not be assumed or interpolated by the contractor; it shall be taken from the project geotechnical report or the footing schedule.
+
+## Allowable bearing pressure (the net allowable soil bearing capacity) is the pressure the soil can carry safely after accounting for overburden, groundwater, and an appropriate factor of safety. IBC Table 1806.2 gives prescriptive presumptive values by soil class — roughly 1,500 psf for clay or silt up to 4,000 psf for sandy gravel — but a site-specific geotechnical report almost always governs and commonly falls in the 1,500 to 6,000 psf range, with competent rock far higher. {note}
+
+## The allowable bearing pressure used for each footing area shall be the value stated in the project geotechnical report or on the footing schedule, not a presumptive code value, unless the building official has explicitly accepted presumptive values for the project.
+
+## Standard Penetration Test N-values reported in the geotechnical investigation, obtained per ASTM D1586, are the primary field data behind the allowable bearing pressure. {note}
+
+## The contractor shall not rely on visual soil assessment in lieu of the geotechnical report to determine allowable bearing pressure.
+
+```datasheet
+label: Allowable Bearing Pressure (per geotechnical report)
+type: range
+unit: psf
+min: 1500
+max: 10000
+step: 250
+default: 2000
+drawing_ref: "footing schedule / geotechnical report"
+```
+
+## Footing depth shall satisfy the deepest of three controls: the minimum embedment below adjacent finished grade, the local frost-protection depth, and the elevation of the competent bearing stratum identified in the geotechnical report.
+
+## The bottom of exterior footings and footings in unheated areas shall be placed below the local frost-protection depth established by the authority having jurisdiction. {note}
+
+## Frost depth varies dramatically by region — effectively zero in the deep South to 48 inches or more across the northern tier — and a footing bottom above frost depth is subject to frost heave. The Engineer of Record translates the local frost depth into a bottom-of-footing elevation on the drawings; the contractor builds to that elevation. {note}
+
+```datasheet
+label: Minimum Footing Embedment Below Adjacent Grade
+type: range
+unit: in
+min: 18
+max: 72
+step: 6
+default: 24
+drawing_ref: "footing schedule"
+```
+
+```datasheet
+label: Frost-Protection Depth (bottom of footing below grade)
+type: range
+unit: in
+min: 0
+max: 72
+step: 6
+default: 36
+drawing_ref: "footing schedule (per AHJ frost depth)"
+```
+
+## Where the bearing stratum is reached at a varying elevation, footings shall be stepped or deepened as directed by the Engineer of Record rather than founded partly on bearing soil and partly on fill.
+
+# Footing Types and Configurations {toc}
+
+## Footing type is selected by the Engineer of Record from the column and wall layout, load eccentricity, proximity to property lines, and soil bearing; each type addresses a specific geometric or load condition, and mis-forming or mis-locating one defeats the design intent in the field. {note}
+
+## The five common shallow-foundation configurations each address a different geometry. Choosing among them is a design decision, but mis-forming or mis-locating one defeats that decision in the field. {note}
+
+### Isolated spread footings support a single column and are reinforced in two directions; square footings carry uniform bar spacing each way, while rectangular footings concentrate a band of reinforcement under the column in the short direction per ACI 318-25. {note}
+
+### Continuous strip (wall) footings run beneath bearing and shear walls, carrying continuous longitudinal reinforcement plus transverse bars; they distribute wall loads as a line load rather than a point load. {note}
+
+### Combined footings carry two or more columns on one footing where individual footings would overlap or where a column sits against a property line, and may be rectangular or trapezoidal in plan to balance bearing pressure. {note}
+
+### Strap (cantilever) footings tie a property-line column footing to an interior footing with a rigid strap beam so the eccentric edge load is balanced and bearing pressures are kept near uniform, per ACI 336.2R. {note}
+
+### Stepped footings accommodate sloped sites by stepping the bearing elevation; each step is limited by code, and horizontal reinforcement must be lapped continuously across each step. {note}
+
+### Thickened spread footings with an integral pedestal carry a formed concrete pier between footing and steel column, common for industrial and pre-engineered metal buildings. {note}
+
+```datasheet
+label: Footing Type
+type: select
+options:
+ - Isolated spread (column) footing
+ - Continuous strip (wall) footing
+ - Combined footing (two or more columns)
+ - Strap / cantilever footing
+ - Stepped footing
+ - Spread footing with integral pedestal
+default: Isolated spread (column) footing
+```
+
+## Stepped footings shall step at a slope no steeper than 1 vertical to 2 horizontal between adjacent bearing elevations, in accordance with IBC 2021 Section 1809.
+
+## Horizontal reinforcement in stepped footings shall be lapped continuously across each step so that the footing acts as a single continuous element.
+
+# Materials {toc}
+
+## Footing concrete strength is selected by the Engineer of Record for structural demand and exposure; 3,000 psi is the common default for light residential work and 4,000 psi for commercial and industrial footings, with higher strengths and sulfate-resistant cement where the geotechnical report identifies aggressive soils. {note}
+
+## ACI 318-25 sets 2,500 psi as the absolute minimum for structural concrete, but durability — not strength — frequently controls the mix. Sulfate exposure classes from the geotechnical report drive cement type and supplementary cementitious materials, specified through the mix design under [[sync/cast-in-place-concrete]]. {note}
+
+### Footing concrete shall be normalweight ready-mixed concrete furnished and tested in accordance with ASTM C94 and [[sync/cast-in-place-concrete]].
+
+### Portland cement shall conform to ASTM C150; Type I/II is the baseline, and a sulfate-resistant type shall be furnished where the geotechnical sulfate-exposure class requires it.
+
+### The specified compressive strength f'c shall not be less than 2,500 psi for any structural footing, in accordance with ACI 318-25.
+
+```datasheet
+label: Specified Compressive Strength (f'c) at 28 Days
+type: select
+unit: psi
+options:
+ - "2500"
+ - "3000"
+ - "4000"
+ - "4500"
+ - "5000"
+default: "4000"
+```
+
+## Reinforcing bar grade is a design selection; Grade 60 deformed bar to ASTM A615 is the corpus default, with ASTM A706 low-alloy bar required where weldability or seismic ductility is specified for dowels and starter bars. {note}
+
+### Footing reinforcement shall be deformed bar conforming to ASTM A615 Grade 60 unless the structural drawings specify otherwise.
+
+### Reinforcement that will be welded, or that is required to meet seismic ductility provisions of ACI 318-25 Chapter 18, shall conform to ASTM A706.
+
+```datasheet
+label: Reinforcing Bar Specification
+type: radio
+options:
+ - ASTM A615 Grade 60 (standard)
+ - ASTM A706 Grade 60 (weldable / seismic)
+default: ASTM A615 Grade 60 (standard)
+```
+
+## Lean concrete used for a mud-mat sub-base is plain, unreinforced, low-strength concrete whose purpose is to provide a clean, stable working surface for setting reinforcement — it is not a structural element. {note}
+
+### Lean concrete for mud-mat sub-bases shall have a specified compressive strength of 2,000 to 2,500 psi and shall be placed without reinforcement.
+
+# Reinforcement, Cover, and Dowels {toc}
+
+## Concrete cast against and permanently exposed to earth requires more cover than formed concrete because the soil interface is irregular and aggressive; the most common footing detailing error is defaulting to beam cover instead of the cast-against-earth value. {note}
+
+## ACI 318-25 requires 3 inches of cover for concrete cast against and permanently exposed to earth — the bottom and sides of a footing poured neat against the excavation or against a mud-mat. Formed faces later exposed to weather require 2 inches. Specifying and verifying the correct cover is what keeps the steel protected for the life of the structure. {note}
+
+### Concrete cover over reinforcement cast against and permanently exposed to earth shall be not less than 3 inches, in accordance with ACI 318-25.
+
+### Concrete cover over formed footing faces exposed to weather or earth after form removal shall be not less than 2 inches.
+
+```datasheet
+label: Concrete Cover — Cast Against Earth
+type: range
+unit: in
+min: 3
+max: 4
+step: 0.5
+default: 3
+```
+
+```datasheet
+label: Concrete Cover — Formed Faces Exposed to Weather
+type: range
+unit: in
+min: 1.5
+max: 3
+step: 0.5
+default: 2
+```
+
+## Footing bar size and spacing are set by the structural design; the layout below is the field deliverable, and reinforcement that cannot develop its required length within the footing must be resolved before the pour, not discovered at it. {note}
+
+## Footing bars are typically #4 through #8. One-way strip footings carry a minimum of two longitudinal bars and temperature-and-shrinkage steel of 0.0018 times the gross area for Grade 60 per ACI 318-25. The governing geometry constraint is that the footing must be thick enough to develop the bottom bars — development length plus cover plus the diameter of the transverse bar. {note}
+
+### Footing reinforcement shall be placed at the size, spacing, and distribution shown on the reinforcement placing drawings and footing schedule.
+
+### Bottom reinforcement shall be supported on bar chairs, dobies, or precast cover blocks sized to maintain the specified cover above the bearing surface or mud-mat; reinforcement shall not be laid directly on soil.
+
+### One-way strip footings shall contain not less than two continuous longitudinal bars and temperature-and-shrinkage reinforcement of not less than 0.0018 times the gross concrete area for Grade 60 bar, per ACI 318-25.
+
+### Footing thickness shall be sufficient to develop the bottom reinforcement, accommodating the required development length plus cover plus the diameter of the transverse bar; where it is not, mechanical couplers or standard hooks shall be provided as detailed by the Engineer of Record.
+
+```datasheet
+label: Primary Footing Bar Size
+type: select
+options:
+ - "#4"
+ - "#5"
+ - "#6"
+ - "#7"
+ - "#8"
+default: "#5"
+drawing_ref: "footing schedule"
+```
+
+```datasheet
+label: Footing Bar Spacing (each way)
+type: range
+unit: in
+min: 6
+max: 18
+step: 1
+default: 12
+drawing_ref: "footing schedule"
+```
+
+```datasheet
+label: Footing Thickness
+type: range
+unit: in
+min: 12
+max: 36
+step: 2
+default: 18
+drawing_ref: "footing schedule"
+```
+
+## Column and wall dowels transfer load from the superstructure into the footing and must be embedded to develop their required length; short dowels are a recurring source of field rework. {note}
+
+### Column and wall dowels shall match the size and number shown on the structural drawings and shall be embedded in the footing to develop their required tension or compression length per ACI 318-25.
+
+### Dowels shall be tied in position and supported so they do not displace during concrete placement; field-bending or repositioning of dowels to fit columns is not permitted without the Engineer of Record's written approval.
+
+```datasheet
+label: Column / Wall Dowel Embedment
+type: range
+unit: in
+min: 12
+max: 48
+step: 2
+default: 24
+drawing_ref: "footing schedule"
+```
+
+# Anchor Bolts and Embedded Plates {toc}
+
+## Anchor bolts set by hand routinely drift out of tolerance, and a bolt pattern that exceeds tolerance forces field reaming or base-plate rework and cascades RFIs to the steel fabricator; a rigid template is the single most effective control. {note}
+
+## Anchor-bolt spacing and the location of the bolt group relative to column gridlines are tight tolerances because the steel base plate is fabricated to fixed hole patterns. Setting bolts to a template that is secured to the formwork — not to loose string lines — is what keeps the steel erectable. {note}
+
+### Anchor bolts and embedded plates shall be set using a rigid template, secured to the formwork or footing forms, that fixes both the bolt-group pattern and its location relative to column gridlines before concrete is placed.
+
+### Anchor-bolt projection above the top of concrete shall match the steel fabricator's requirements, accounting for base-plate thickness, leveling nuts, and grout space.
+
+### Anchor bolts shall be set within a spacing tolerance of ±1/16 inch bolt-to-bolt within a group and a location tolerance of ±1/8 inch on the group centerline relative to the established column gridline, unless the structural drawings specify tighter tolerances.
+
+### Anchor bolts and embedded plates shall be cleaned of concrete and protected from damage until the supported steel is erected.
+
+### Anchor-bolt threads shall be protected during the pour.
+
+```datasheet
+label: Anchor Bolt Diameter
+type: select
+unit: in
+options:
+ - "0.75"
+ - "0.875"
+ - "1.0"
+ - "1.25"
+ - "1.5"
+default: "0.75"
+drawing_ref: "anchor-bolt schedule"
+```
+
+```datasheet
+label: Anchor Bolt Setting Method
+type: radio
+options:
+ - Rigid template secured to formwork
+ - Cast-in template with leveling provision
+default: Rigid template secured to formwork
+```
+
+```datasheet
+label: Anchor Bolt Group Centerline Tolerance
+type: range
+unit: in
+min: 0.0625
+max: 0.25
+step: 0.0625
+default: 0.125
+```
+
+# Keyways and Construction Joints {toc}
+
+## Shear transfer between a footing and the wall or stem above it is not automatic; a keyway or a roughened, intentionally bonded construction joint must be specified, or the joint becomes a smooth plane that cannot transfer horizontal shear. {note}
+
+## At the footing-to-stem-wall interface, the second pour bonds to the first only as well as the joint is prepared. A formed keyway provides a mechanical shear key; alternatively, a roughened construction joint to a full amplitude provides shear-friction capacity. Dowels across the joint develop tension. The detail must be on the drawings and built as shown. {note}
+
+### A keyway or an intentionally roughened construction joint shall be provided at the footing-to-stem-wall or footing-to-grade-beam interface as detailed by the Engineer of Record.
+
+### Where a roughened construction joint is used in lieu of a keyway, the surface shall be intentionally roughened to a full amplitude of approximately 1/4 inch and cleaned of laitance before the subsequent placement.
+
+### Vertical dowels crossing the construction joint shall be sized, spaced, and embedded as shown on the structural drawings to develop the required shear-friction and tension across the joint.
+
+```datasheet
+label: Footing-to-Wall Shear Transfer
+type: radio
+options:
+ - Formed keyway
+ - Roughened construction joint (≈1/4 in amplitude)
+ - Both keyway and dowels
+default: Formed keyway
+drawing_ref: "footing-to-wall detail"
+```
+
+```datasheet
+label: Keyway Width
+type: range
+unit: in
+min: 1.5
+max: 6
+step: 0.5
+default: 2
+drawing_ref: "footing-to-wall detail"
+```
+
+```datasheet
+label: Keyway Depth
+type: range
+unit: in
+min: 1.5
+max: 4
+step: 0.5
+default: 1.5
+drawing_ref: "footing-to-wall detail"
+```
+
+# Lean-Concrete Sub-Base (Mud-Mat) {toc}
+
+## A mud-mat protects reinforcement cover and alignment on soft or wet subgrade, where bars set on loose soil sink, lose cover, and drift out of position; it is a working surface, not a structural layer. {note}
+
+## On firm, dry subgrade a mud-mat is optional. On soft or saturated soil it earns its cost: a thin lean-concrete slab gives a clean, level surface that holds chairs and keeps the bottom mat at the right elevation. The decision should follow a soil-condition trigger rather than contractor preference. {note}
+
+### A lean-concrete mud-mat shall be provided where the subgrade is soft, where groundwater is within 12 inches of the bearing elevation, or where the geotechnical report or drawings require it.
+
+### Where used, the mud-mat shall be a minimum of 3 inches thick and shall extend not less than 3 inches beyond the footing perimeter to provide working clearance.
+
+### Reinforcement shall not be placed directly on a subgrade that is soft enough to displace under foot or equipment traffic; a mud-mat or equivalent stable working surface shall be provided first.
+
+```datasheet
+label: Lean-Concrete Mud-Mat
+type: radio
+options:
+ - Required (soft / wet subgrade)
+ - Not required (firm, dry subgrade)
+ - Per geotechnical recommendation
+default: Not required (firm, dry subgrade)
+```
+
+```datasheet
+label: Mud-Mat Thickness
+type: range
+unit: in
+min: 3
+max: 6
+step: 1
+default: 3
+```
+
+# Tolerances {toc}
+
+## Footing dimensional tolerances follow ACI 117 and matter because a footing that is mislocated, undersized, or out of plumb at the pedestal can shift bearing pressure, reduce cover, or prevent the supported column from landing on its base. {note}
+
+### Footing location, plan dimensions, top elevation, and thickness shall be within the tolerances of ACI 117 unless the structural drawings specify tighter limits.
+
+### Reduction of any footing plan dimension below the scheduled dimension shall not be permitted; oversizing within the excavation is acceptable provided cover and reinforcement position are maintained.
+
+### Pedestals and formed stem walls cast monolithically or jointed to footings shall be plumbed within the ACI 117 tolerance for the formed surface.
+
+```datasheet
+label: Footing Plan-Dimension Tolerance
+type: range
+unit: in
+min: 0
+max: 2
+step: 0.5
+default: 2
+```
+
+# Installation {toc}
+
+## Footing execution proceeds from accepted bearing surface to verified embeds in a fixed sequence; skipping the verification steps is where defects become permanent. {note}
+
+## The execution sequence is: prepare and obtain acceptance of the bearing surface, place any mud-mat, set and tie reinforcement and dowels to the correct cover, set anchor-bolt templates and embeds, complete the pre-pour inspection, then place concrete under [[sync/cast-in-place-concrete]]. Each gate exists because the condition it checks cannot be verified after the next step covers it. {note}
+
+### The contractor shall coordinate excavation, dewatering, and subgrade preparation with [[sync/earthwork]] so that the bearing surface presented for inspection is the surface on which the footing will bear.
+
+### Loose, disturbed, or over-excavated material at the bearing surface shall be removed and replaced with lean concrete or compacted engineered fill as directed by the geotechnical engineer before reinforcement is set.
+
+### Water shall be removed from footing excavations and concrete shall not be placed in standing water or on a frozen or frost-affected bearing surface.
+
+### Reinforcement, dowels, anchor-bolt templates, and embedded plates shall be set, tied, and secured against displacement before concrete placement begins.
+
+### The pre-pour inspection shall be completed and signed before concrete placement begins.
+
+### Footing concrete shall be placed, consolidated, finished, and cured in accordance with [[sync/cast-in-place-concrete]]; this standard does not restate those requirements.
+
+### Concrete shall be placed continuously within each footing; planned construction joints shall occur only where shown on the drawings and shall be prepared as specified for keyways and construction joints.
+
+## Backfill placed against a footing or stem wall before the concrete has gained adequate strength can crack or displace the element; a strength gate prevents premature loading. {note}
+
+### Backfill shall not be placed against footings or stem walls, and surcharge loads shall not be applied, until the concrete has attained at least 70 percent of its specified compressive strength, verified by 7-day cylinder breaks or by maturity, and until any required bracing is in place.
+
+### A hold point for inspection shall be observed before backfill is placed against foundation elements, and backfill operations shall be coordinated with [[sync/below-grade-waterproofing]] where waterproofing or drainage is installed.
+
+```datasheet
+label: Minimum Strength Before Backfill / Surcharge
+type: range
+unit: "% f'c"
+min: 50
+max: 100
+step: 5
+default: 70
+```
+
+# Eccentricity and Overturning {toc}
+
+## Footings carrying combined axial load and moment — from frame action, wind, or seismic demand — must be checked for the bearing-pressure distribution across the base, not just the average pressure; a footing that looks adequate on average can overstress one edge or partially uplift. {note}
+
+## For a footing under axial load plus moment, keeping the load resultant within the middle third of the base (eccentricity not exceeding B/6) keeps the entire base in compression. Larger moments, common in seismic design, may allow partial uplift only with a documented analysis. Footings subject to significant moment are a design responsibility, but specifications that never require the check invite undersized footings. {note}
+
+### Footings subject to combined axial load and moment shall be designed by the Engineer of Record for the resulting non-uniform bearing-pressure distribution and for overturning stability.
+
+### Where the load resultant on an eccentrically loaded footing falls outside the middle third of the base, the partial-uplift condition shall be supported by a documented analysis from the Engineer of Record, in accordance with ASCE/SEI 7-22 load combinations.
+
+### The contractor shall not substitute a symmetric footing for a combined or strap footing shown on the drawings, as these types exist specifically to manage eccentric loading.
+
+# Delivery, Storage, and Handling {toc}
+
+## Footing materials are largely delivered just in time, but reinforcement and embeds staged on site must be protected so that what is installed still meets the material specifications. {note}
+
+### Reinforcing bar shall be stored off the ground on supports and protected from contaminants that would impair bond, in accordance with [[sync/concrete-reinforcement]].
+
+### Anchor bolts, embedded plates, and templates shall be stored to protect threads and faying surfaces from damage, corrosion, and concrete contamination until set.
+
+### Ready-mixed concrete shall be delivered, discharged, and tested within the time and condition limits of ASTM C94 and [[sync/cast-in-place-concrete]].
+
+# Warranty {toc}
+
+## Foundation defects surface slowly and are expensive to access once a structure is built over them, so the warranty obligation centers on workmanship and on correcting deficiencies revealed by acceptance testing and inspection. {note}
+
+### The Contractor shall warrant footing work against defective materials and workmanship for the period stated in the Contract, and shall correct concrete that fails to meet the specified compressive strength as determined under ACI 318-25.
+
+### The Contractor shall remain responsible for correcting footing defects attributable to placing on unaccepted bearing surfaces, omitted bearing inspections, or backfill placed before the required strength was attained.
+
+# Spare Materials and Records {toc}
+
+## Shallow foundations are buried in service, so the durable deliverable is the record set; spare physical materials are minimal. {note}
+
+### The Contractor shall deliver to the Owner the complete record set of bearing-inspection reports, pre-pour inspection records, cylinder break reports, and as-built footing and anchor-bolt locations.
+
+### The Contractor shall retain unused project-specific embed templates until final acceptance in case anchor-bolt rework is directed.