Previous poured concrete foundation walls projects and or serving but not limited to these cities in Ohio: Cleveland, Akron, Canton, Parma, Lakewood, Lorain, Elyria, Euclid, Mentor, Strongsville, Cuyahoga Falls, Columbus, Newark, Dublin, Grove City, Lancaster, Delaware, Reynoldsburg, Cincinnati, Dayton, Hamilton, Middletown, Fairfield, Springfield, Kettering, Beavercreek, Huber Heights
| Specification | Typical requirement | Governing basis |
|---|---|---|
| Minimum depth | Not less than 12 inches below undisturbed ground surface, and below the local frost line | Ohio Residential Code 403.1.4, with frost depth taken from Table R301.2(1) as filled in by the local jurisdiction |
| Width | Commonly twice the wall thickness, so a 10 inch wall gets a 20 inch footing as a starting point | Long-standing design practice, adjusted for soil bearing capacity and load. Confirm against approved drawings and your AHJ |
| Thickness | Not less than the projection beyond the wall face, 6 inches minimum in typical residential work | Common design practice for plain concrete footings. Verify on the stamped plan |
| Rebar | Frequently two continuous longitudinal bars in the bottom third, lapped at splices and hooked at corners | Specified by the designer or engineer, not by a universal residential code minimum. Read it off the foundation plan |
| Concrete strength | Commonly 3,000 psi at 28 days for footings, higher where the plan calls for it | Mix design on the approved drawings and the submitted batch ticket |
| Projection | Equal on both faces of the wall unless the plan shows an offset, and never more than the footing thickness | Derived from footing width minus wall thickness, divided by two |
A concrete footing is the widened base under a foundation wall that spreads building load into the soil. In Ohio it must bear at least 12 inches below undisturbed grade and below the local frost line, be wide enough for the bearing soil, and be at least as thick as it projects past the wall.
This article is the numbers reference: what each dimension on a footing detail means, where the requirement comes from, and how to check a pour against the drawing. For the process side, the footing types, mix selection and installation sequence, read our complete guide to concrete footings, the companion piece to this one.
Depth: What Actually Sets the Number
Depth is the requirement builders get wrong most often, because two separate rules apply and both have to be satisfied.
Ohio Residential Code 403.1.4 requires exterior footings to bear not less than 12 inches below the undisturbed ground surface. That is a floor, not a target. The same section also requires footings to extend below the frost line, and for the frost line it points to Table R301.2(1).
Table R301.2(1) is not filled in at the state level. Ohio leaves the frost depth cell to each jurisdiction. There is no statewide Ohio frost number, and any figure quoted as “the Ohio frost depth” is either a local value borrowed from one city or an invention.
In practice the deeper of the two controls. Where the local frost depth is 32 inches, the figure the City of Columbus publishes, the 12 inch rule never enters your bottom of footing elevation. On an interior footing in a heated basement, the 12 inch rule is often the governing number instead.
Confirming the value is a phone call, not a lookup. Which Ohio jurisdictions publish a figure and which do not is covered in concrete footing depth and Ohio frost line requirements. Get the number from the department that will inspect the footing.
Depth is measured to the bottom of the footing
The required depth is to the bearing surface at the bottom of the footing, not the top of it. At the 38 inch frost depth Summit County publishes, a 10 inch thick footing puts the top of the footing around 28 inches below grade, and the excavation deeper still for stone and working room.
Width and Projection: Where the Number Comes From
Footing width exists to spread load. The wall delivers a line load in pounds per linear foot, the soil carries a pressure in pounds per square foot, and the footing is the transition. Divide load by allowable bearing pressure and you have the required width.
The rule of thumb most crews carry in their heads is that the footing is twice the wall thickness. A 10 inch wall gets a 20 inch footing as a minimum. An 8 inch wall gets 16 inches. That rule is a reasonable starting point for a one or two story house on competent soil, and it is why the numbers on so many residential plans look the same from job to job.
It stops being reliable in three situations: weak or organic soil with low bearing capacity, heavier structures such as three stories or masonry veneer, and any footing carrying a concentrated load from a column or beam pocket. Those are sized from the load, not from the rule of thumb.
Projection is the leftover. Subtract the wall thickness from the footing width and split the difference across both faces, so a 20 inch footing under a 10 inch wall projects 5 inches per side. That number drives the thickness requirement below, and it is the dimension your form crew is holding on the wall line.
For worked examples at common house sizes, see concrete footing sizes for a house in Ohio. If you are still settling on the wall dimension that feeds this calculation, foundation wall thickness in Ohio covers that side of it.
Thickness and Concrete Strength
Footing thickness is governed by the projection. The standard practice is that thickness is not less than the projection beyond the face of the wall, with 6 inches as the practical residential minimum. The reason is shear. Concrete projecting past the wall acts as a short cantilever, and if it is too thin relative to how far it sticks out, it cracks off diagonally rather than transferring load down into the soil.
Run the arithmetic. A 10 inch wall on a 20 inch footing projects 5 inches, so 6 inches of thickness clears both the projection rule and the minimum. Widen that footing to 24 inches for poorer soil and the projection becomes 7 inches, which pushes thickness to 7 inches or more. Widening without thickening creates a detail that does not work.
Concrete strength for residential footings is commonly specified at 3,000 psi at 28 days, higher where the design or exposure calls for it. Treat the approved drawing as the requirement and the batch ticket as the proof, and confirm both with your AHJ, since some jurisdictions specify above that baseline.
Rebar in a Concrete Footing: Why It Is There and Where It Goes
A plain concrete footing works in compression. Rebar is added when the footing has to work in tension, which happens whenever the soil under it is not uniform. Soft spots, backfilled utility trenches, differential settlement and expansive clay all put a footing into bending, and steel keeps a bending footing from cracking through.
The common residential detail is two continuous longitudinal bars in the lower portion of the section where tension develops, with cover maintained so the steel stays embedded in concrete rather than sitting on dirt. Bars are lapped at splices and hooked or continued around corners. Pushing bars into concrete after the pour is not equivalent to supporting them on chairs before it.
Where the residential code does not mandate a bar schedule, the requirement comes from the designer. Rebar in a footing is usually a specified item rather than a code minimum, so the authority is the stamped foundation plan. Follow what is drawn, and if the plan is silent where you expect steel, ask before you pour.
Placement, cover, lap length and bar sizing are covered in more depth in rebar and steel reinforcement in concrete foundations.
The Keyway and the Footing to Wall Connection
The footing and the wall are poured at different times, so the joint between them is a cold joint. Left flat and untreated it can transfer vertical load but resists very little lateral movement, and it is a path for water.
A keyway is a recess formed down the center of the top of the footing with a beveled key set into the wet concrete. The wall pour fills it, and the resulting tongue resists sliding at the wall base under backfill pressure. Where the plan calls for dowels instead, vertical bars are set at a specified spacing and lapped into the wall steel.
Either way, check the connection before the wall crew shows up. A key formed off center, a key that collapsed green, or dowels at the wrong spacing all get expensive once the wall is standing. This joint is also where waterproofing and drainage detailing begins.
Common Footing Failures and How Precision Layout Prevents Them
Almost every footing problem traces back to one of five things, most set in motion before concrete is ordered.
- Bearing too shallow. The footing sits above the local frost line, freeze thaw heave lifts it seasonally, and the wall above cracks. The fix is confirming the local frost figure before excavation, not after.
- Bearing on disturbed soil. The dig went too deep and was brought back up with loose spoil. Undisturbed soil or compacted engineered fill is the requirement, and a footing on soft fill settles no matter how well it is reinforced.
- Too narrow for the soil. The rule of thumb was applied to soil that could not carry the resulting pressure. Differential settlement follows.
- Out of position. Every dimension is correct but the footing is off the building line, leaving the wall bearing near the edge under an eccentric load the design never anticipated.
- Out of level. Steps and elevation changes not held cleanly leave the wall crew shimming and the error chasing up through the structure.
Positional errors are the avoidable category, and they are a layout problem rather than a concrete problem. We run a Total Robotics Station so building lines, steps and elevations are set from survey control rather than tape pulled off batter boards, and our in-house CAD engineer works the foundation plan before anyone breaks ground.
How to Read Footing Specs Off a Foundation Plan
All of this lives in two places on a stamped set: the foundation plan and the typical footing detail. Work them in this order.
- Find the typical wall section. It carries footing width, thickness, wall thickness, reinforcement callouts and the bottom of footing elevation. This is the sheet the footing crew builds from.
- Read the bottom of footing note. It is either an elevation tied to a datum or a dimension below finished grade. Reconcile it with local frost depth and the 12 inch minimum below undisturbed grade.
- Check the width against the wall. Compute projection and confirm the drawn thickness is at least the projection.
- Read the rebar callout literally. Bar size, quantity, spacing, lap length and cover. If corner and intersection detailing is not shown, ask.
- Note every step and change in footing size. Garage and porch footings, column pads and beam pockets differ from the typical section and are routinely missed.
- Confirm the concrete strength note and the required inspection points with the building department. Most jurisdictions inspect the open trench with steel in place, before concrete.
Anything the plan does not answer goes to the engineer of record or the AHJ. Concrete in the ground at the wrong elevation is not something you adjust later. For the permitting side, see foundation permits in Ohio, and for scope, our concrete footings service.
Get the Numbers Confirmed Before You Pour
If you want a second read on a footing detail before the trench is open, send the plans over. We have poured footings and foundations across Ohio since 2008 and handle the full package from excavation through footers, walls, waterproofing and backfill, so the dimensions get checked by the crew that will build to them.
Email contact@armadapouredwalls.com or Request a Quote and we will get back to you with a real answer on depth, width and reinforcement for your site.