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Footings & Foundations — ICC B1 Practice Questions

67 questions · 16% of the ICC B1 exam

Worked questions

1. A continuous footing is formed 26 inches wide and 8 inches thick, centered under an 8-inch-thick concrete foundation wall. Judging only the geometry of the footing, what should the inspector conclude?

  • AIt is acceptable, because the projection on each side is well above the 2-inch minimum.

    The 2-inch value is only the lower bound; this projection fails the upper bound tied to footing thickness.

  • BIt is acceptable, because a wider footing always spreads the load more conservatively than a narrow one.

    Extra width without extra thickness overhangs the wall and puts the concrete into bending it cannot carry.

  • It is unacceptable, because each side projects 9 inches, which is more than the 8-inch thickness of the footing.
  • DIt is unacceptable, because a footing projection may never exceed 6 inches under any wall.

    No fixed 6-inch cap exists; the ceiling on projection is the thickness of the footing itself, which varies.

Why C is correct

Projection equals half of the footing width minus the wall thickness: 26 minus 8 is 18, and half of that is 9 inches. The code allows a projection of at least 2 inches but no more than the footing thickness, which is 8 inches here. Nine is greater than eight, so the geometry fails and the footing must be deepened to 9 inches or trimmed to 24 inches wide.

What this question is testing

Applying a two-sided limit rather than a single minimum, and computing projection correctly by subtracting the wall thickness first and then halving. It also checks whether the candidate resists the intuition that more concrete is automatically safer, which is the trap built into the wrong choices here.

On the job

This one shows up whenever a trench gets sloppy and the crew simply forms wider than the plan. Widening looks harmless and even generous, so it rarely gets questioned by anyone on site. The inspector who knows the projection rule reads it as a thickness problem instead: a 26-inch footing needs 9 inches of depth, and adding an inch of concrete depth is cheap while a cracked overhang discovered after backfill is not. Expect to see it most on soft-soil lots where the plan already calls for a wide footing.

Memory technique

Projection lives between two and the thickness: never stubby, never longer than the footing is deep.

Exam tip

Sketch the footing and wall in cross section before you compute; the halving step is the one candidates skip.

Where to look it up

IRC Chapter 4, the minimum size paragraph under R403.1 where footing width, thickness and projection are defined together.

2. The plans give a total load of 2,400 pounds per lineal foot on a continuous footing and a presumptive soil load-bearing value of 1,500 pounds per square foot. The crew has formed the footing 16 inches wide. What is the correct finding?

  • AThe footing is adequate as formed, since 16 inches of width is already twice the nominal thickness of the foundation wall standing on top of it.

    Twice the wall thickness is a familiar rule of thumb for footing projection, and it says nothing about the soil. Width has to be checked against the load per foot of wall and the bearing value of the soil, which is the calculation here.

  • BThe footing must be 24 inches wide, because a footing is always three times the thickness of the foundation wall standing above it.

    Three times the wall thickness is a proportion someone remembered, not a code requirement. It happens to be conservative on strong soil and unconservative on weak soil, because it never looks at the load or at the bearing capacity.

  • CThe footing is adequate as formed, provided the mix design is increased by 1,000 psi to carry the additional soil pressure.

    Concrete strength governs the footing's own bending and shear, not how much soil it needs beneath it. A stronger mix in a 16-inch footing still delivers the same load onto the same area of ground.

  • The footing is undersized, because roughly 19.2 inches of bearing width is needed to keep soil pressure within 1,500 pounds per square foot.

Why D is correct

Required width equals load per foot divided by allowable soil pressure: 2,400 divided by 1,500 gives 1.6 feet, or 19.2 inches, so the practical minimum is 20 inches. The 16-inch form leaves only 1.33 square feet of bearing per foot of wall and pushes soil pressure to roughly 1,800 pounds per square foot, above the value the design relied on.

What this question is testing

Running the basic bearing calculation in the direction an inspector actually needs it, from a known load and a stated soil value to a required width, and then comparing that width to what is formed on the ground. It also tests recognizing that material strength and bearing width solve different problems.

On the job

Soil bearing shows up in inspection when a plan is based on a value the site does not deliver, or when the crew simply forms to the trencher width they own. If the plan lists a presumptive value and the trench bottom is obviously soft, wet, or filled, that is the moment to require a geotechnical evaluation rather than accept the number on paper. Widening a footing before concrete is a half-hour of shovel work; underpinning a settled corner is a structural repair.

Memory technique

Pounds per foot over pounds per square foot leaves feet: the units hand you the width.

Exam tip

Load divided by soil value gives square feet per foot of wall, which reads directly as feet of width; convert to inches last.

Where to look it up

IRC Chapter 4, footing sizing, and the presumptive load-bearing values table for soil classes.

3. Along one 15-foot length of continuous footing trench, the trench bottom drops a total of 24 inches from one end to the other, and the crew plans to pour it as a single sloping ribbon of concrete. How should the inspector judge that trench?

  • AIt is acceptable, because the bottom of a footing may be allowed to slope as steeply as one unit vertical in five units horizontal without any step.

    One in five is twice the slope the code allows on the bottom of a footing. Recalling that there is a limit but doubling the number lets a run of footing be poured on a grade that will want to slide under load.

  • BIt is acceptable, because only the top surface of a footing is required to be level, and the bottom may simply follow the ground.

    The top surface has to be level and so does the bottom, within a maximum slope. Stopping at the top surface misses the reason for the rule, which is that a sloping bearing surface pushes the footing downhill under load.

  • It is not acceptable, because the bottom slopes about one in seven and a half, steeper than the one-in-ten limit, so this run has to be stepped.
  • DIt is not acceptable, because a footing on a sloping site has to be poured dead level in one continuous piece with no steps at all in it.

    Stepped footings are exactly what the code prescribes on a sloping site. Requiring one continuous level pour would mean excavating the entire run down to the lowest elevation, which this section is written to avoid.

Why C is correct

Convert both dimensions to the same unit: 15 feet is 180 inches, and 24 inches of drop over 180 gives a slope of one in seven and a half. That is steeper than the one-in-ten maximum for the bottom of a footing, so the run must be broken into level steps. Stepping also lets the top surface stay level, which the code requires everywhere.

What this question is testing

Converting a fall and a run into a slope ratio and comparing it to a code limit, plus knowing that the top and the bottom of a footing are governed by two different requirements. It also tests knowing that stepping is the accepted remedy rather than a defect in itself.

On the job

Hillside footings are where excavation crews take the most liberties, because benching a trench into steps costs time and every step needs its own forms. The failure mode is real: concrete poured on a steep grade segregates, the top surface finishes out of level, and the sill plate then bears unevenly. On a walkaround, sight down the trench with a level or laser rather than eyeballing it, and record the fall over a measured length so the correction notice carries a defensible number.

Memory technique

Top level, bottom no steeper than one in ten, and step it when the hill wins.

Exam tip

Put the run and the rise into the same units before forming the ratio; mixing feet and inches is the classic slip here.

Where to look it up

IRC Chapter 4, the paragraph on footing slope and stepped footings, near the minimum depth provisions.

4. The plans size the wall thickness and reinforcement from a table indexed by unbalanced backfill height. With an interior concrete slab on grade present, where does the inspector measure that height from and to?

  • AFrom the top of the foundation wall down to the exterior finished grade, because that is the portion of the wall exposed above the soil.

    This measures the exposed part of the wall rather than the soil bearing on it. Unbalanced backfill is the depth of earth pushing on one side with nothing balancing it on the other.

  • BFrom the exterior finished grade down to the bottom of the footing that supports the wall, because the footing restrains the base of it.

    Running the measurement to the bottom of the footing adds the footing depth to the height and moves you into a heavier row of the table. The restraint is the slab, which sits above the footing.

  • From the exterior finished grade down to the top of the interior slab on grade, because the slab braces the base of the wall.
  • DFrom the top of the wall down to the top of the interior slab, because the slab is what stops the wall moving at its base.

    Starting at the top of the wall rather than the exterior grade counts wall that has no soil against it. The measurement begins where the earth begins, at the exterior finished ground level.

Why C is correct

The measurement captures the height of soil that is pushing on the wall with nothing pushing back. The top of the measurement is the exterior finished ground level, and the bottom is the level at which the inside of the wall is restrained. An interior slab on grade provides that restraint at its top surface, so the height is measured to the slab, which is why finishing the slab before backfill can reduce the design height.

What this question is testing

Whether the candidate can define unbalanced backfill height precisely enough to use the prescriptive foundation wall tables, including which interior element establishes the lower point of the measurement and how a slab on grade changes it.

On the job

Plan review sets the wall from the table, but the inspector is the one who confirms the site matches the assumption. Final grading frequently ends up higher than the plan showed, especially where a walkout drops away on one side and the fill rises on another, and a wall designed for 6 feet of unbalanced fill can end up with 8. When you see the grading contractor raising the exterior, go back to the table row the plan used and confirm the wall is still adequate.

Memory technique

Outside dirt down to inside floor: the slab is where the wall stops needing help.

Exam tip

Unbalanced fill is measured from the outside ground down to whatever holds the inside face of the wall, never to the footing bottom.

Where to look it up

IRC Chapter 4, the definition used with the concrete and masonry foundation wall tables in R404, and the backfill provisions in the same section.

5. Under the floor you find stacked form boards from the foundation pour, scrap lumber, a bag of set concrete, and several buried stumps left in the ground surface. What is the correct disposition of the crawl space?

  • AApprove it, because loose lumber left under a floor is a housekeeping matter rather than a code item for an inspector to call.

    The code names vegetation, organic material and construction debris as items to be removed, which makes this an inspection item rather than a matter of tidiness. Buried wood in a crawl space feeds decay fungi and termites.

  • BApprove it if the debris is stacked up clear of the ground on concrete blocks so that it can stay dry.

    Getting the wood up off the ground slows decay and leaves the food source in place. The requirement is removal, because a crawl space stays damp and any cellulose left under the floor eventually supports fungi or insects.

  • Require the vegetation, organic material, wood forms and construction debris to be removed before the building is occupied.
  • DRequire only that a vapor retarder be spread over the debris and the ground surface together as one layer.

    A vapor retarder controls moisture rising out of the soil, and it does not neutralize material lying on top of it. Covering the debris seals it under a sheet along with the moisture already in it.

Why C is correct

Under-floor areas must be cleaned of vegetation and organic material, and wood forms and construction materials must be removed before occupancy. Buried stumps and scrap lumber are a termite and decay source inches from the joists, and once the crawl space is closed up nobody looks again for years. Requiring removal before occupancy is exactly what the code contemplates and is enforceable at final.

What this question is testing

Whether the candidate knows that site preparation and debris removal are enforceable code requirements with an occupancy trigger, and understands the decay and termite reasoning well enough to reject the plausible half-measures of stacking or covering the material.

On the job

Crawl spaces are where a job hides its trash, and the last trade in rarely goes back. Open the hatch on every final, put a light in, and look at the ground rather than just the framing. Buried stumps and grade stakes are the ones crews argue about, because digging them out means hand work in an 18-inch space. Tie the correction to occupancy rather than to a framing item so the schedule pressure works in favor of the fix.

Memory technique

Nothing wood stays in the dirt: forms out, stumps out, scrap out, before anyone moves in.

Exam tip

Anything cellulose left in contact with soil under a house is a code violation, not a cleanup preference.

Where to look it up

IRC Chapter 4, R408 for under-floor space including removal of debris, plus the site preparation requirements ahead of slab and foundation work.

6. The approved plans specify 3,000 psi concrete for the foundation, but the delivery ticket in the driver hand describes a 2,500 psi mix, and no revision has been submitted to the department. What is the correct action?

  • ARelease the placement, because 2,500 psi is the code minimum for structural concrete and is therefore acceptable in a footing of any size.

    A code minimum is a floor, not a substitute for what the design calls for. Approved plans become the enforceable document once the permit issues, and a mix below the specified strength is a change to that document.

  • BRelease the placement if the driver adds water at the site to improve the workability of the mix just before it is discharged.

    Adding water at the site lowers strength rather than raising it, and the water content is fixed by the mix design in any case. This trades a documented shortfall for an undocumented one.

  • CLet the pour proceed and then require core testing of the finished footing before any of the framing is allowed to start.

    Core testing is a way to evaluate concrete already in place when there is no better option. Planning for it before the pour accepts a known deficiency and pushes the argument to the point where the fix costs the most.

  • Hold the placement, because the mix delivered has to match the strength shown on the approved plans unless a revision is approved.

Why D is correct

Work has to be built in accordance with the approved documents, and a lower-strength mix than the plans specify is a deviation that requires approval before it is placed. Stopping the placement preserves every option: order the correct mix, or submit a revision for the building official to evaluate. Once the concrete is in the ground, the only verification left is destructive and the only remedy is expensive.

What this question is testing

Whether the candidate treats the approved construction documents as enforceable, and whether they act at the moment when action is cheap. It also tests knowing which verification tools belong before placement and which belong after, and rejecting field alterations that degrade the material.

On the job

Delivery tickets are the cheapest verification tool on a concrete job, and reading them takes thirty seconds. Mix-ups happen constantly when a plant is serving several jobs, and dispatch often sends the standard house mix regardless of what the plans said. Note the ticket number, the mix designation, the batch time, and the water added on site. If the strength is short, tell the superintendent before the truck discharges, because after that the conversation is about removal rather than about the next load.

Memory technique

Read the ticket before the chute drops: strength is easy to check and impossible to fix.

Exam tip

When plans and code minimums disagree, the more restrictive requirement on the approved documents controls the inspection.

Where to look it up

IRC Chapter 1 for construction in accordance with approved documents, and Chapter 4 for concrete material requirements and weathering-based strength tables.

7. Along the bottom 12 inches of one wall the concrete is coarse and porous with open voids between the stones, and in two places a horizontal bar is exposed to view. What is the correct inspector action?

  • AApprove the wall, because the affected zone sits below the finished grade and will be hidden by backfill against the outside face in any case.

    Being out of sight is not the same as being sound. Honeycombed concrete has reduced strength and an open path for water, and backfill loads that wall harder than anything it sees later, so the hidden zone is where it matters.

  • BApprove the wall once the crew rubs a cement slurry across the porous area so that the open surface is sealed against water.

    A slurry rub is a cosmetic surface treatment. It closes the appearance of the voids without restoring section or bond, and the code asks for defective concrete to be evaluated and repaired by a method the official approves.

  • CApprove the wall if the test cylinders taken from that same truck break at or above the compressive strength specified.

    Cylinder breaks report the strength of the mix as delivered, not the strength of the wall as placed. Honeycombing comes from placement and consolidation, so a passing cylinder says nothing about the zone in question.

  • Withhold approval and require the defective concrete to be evaluated and repaired by an approved method before dampproofing and backfill.

Why D is correct

Honeycombed concrete has neither the strength nor the cover the design assumed, and it sits at the base of the wall where load and water pressure are greatest. Approval is withheld until the unsound material is cut out and repaired by a method the building official accepts, and that repair must happen before anything covers it.

What this question is testing

Whether the candidate reads honeycombing as a structural and durability defect rather than a finish complaint, and understands that strength testing of cylinders does not certify in-place consolidation.

On the job

Honeycombing clusters at the bottom of tall walls, at window bucks and around congested steel, and it is usually the result of a pump crew placing fast without a vibrator. The right time to see it is the hour the forms come off, which is often the same hour the dampproofing sprayer shows up. Once tar covers the wall the defect is invisible until the basement leaks. Inspectors in busy jurisdictions ask builders to schedule the wall inspection before, not after, the coating.

Memory technique

If you can see the rock and the rebar, there is no concrete doing the work.

Exam tip

Watch for choices that substitute a test result or a cosmetic coating for an actual repair of missing material.

Where to look it up

IRC Chapter 4, the concrete materials and placement requirements under R402 and R404.

8. The truck on site is placing the attached garage floor and the open front porch, and the ticket describes a mix designed for 3,000 pounds per square inch at 28 days with air entrainment. Judging only the specified compressive strength, how should the inspector rule?

  • AAccept it, because 3,000 pounds per square inch is the minimum for any concrete placed in a dwelling in a severe weathering area of the map.

    Three thousand is the figure for basement walls, foundation walls and interior slabs on the severe weathering map. Flatwork exposed to weather and to de-icing chemicals steps up to 3,500.

  • BAccept it, because the entrained air in this mix permits the specified strength to be reduced one step below the value shown in the table.

    Air entrainment is an additional requirement for exposed flatwork, not a trade that buys back strength. Both apply at once, so the mix has to carry the air and the 3,500 figure together.

  • Reject the mix, because garage floors and porch slabs exposed to weather in a severe weathering area are specified at 3,500 pounds per square inch.
  • DReject the mix, because every slab placed on ground has to be specified at 4,000 pounds per square inch in a severe weathering area such as this one.

    Four thousand is above anything the table sets for residential work, and interior slabs sit well below it. Rejecting the mix for that number asks the builder for concrete the code does not require.

Why C is correct

The strength table sets a higher minimum for garage floor slabs, porches and carport slabs exposed to the weather in moderate and severe weathering areas, because those surfaces face freeze-thaw cycling and de-icing salts. That minimum is 3,500 pounds per square inch, so a 3,000 mix is short and the pour should be stopped before it goes down.

What this question is testing

Whether the candidate reads the strength table by exposure category rather than by a single remembered number, and knows that air entrainment and compressive strength are independent requirements for exposed flatwork.

On the job

Ticket checking takes thirty seconds and catches the single most common concrete defect, which is the batch plant sending the house mix to a flatwork pour. Salt-damaged garage aprons and scaled porches are among the most frequent early callbacks in cold climates, and they trace directly to strength and air content. Carry the weathering probability map for your jurisdiction; the whole table hangs off which zone you are in.

Memory technique

Anything the weather and the salt truck can reach gets the higher number.

Exam tip

Sort concrete strength questions by where the concrete goes first and by the weathering zone second.

Where to look it up

IRC Chapter 4, the minimum specified compressive strength table under R402.2 and the weathering probability map in Chapter 3.

9. The soils information for this lot classifies the ground as a well-drained gravel and sand mixture in Group I, the excavation has stayed dry through two weeks of weather, and no perforated pipe or drainage stone has been placed around the footing of the basement wall. What should the inspector conclude?

  • AA drain is required, because every foundation wall enclosing a basement must have a perimeter drain regardless of the soil.

    The requirement is not absolute; it is written with a soil-based exception.

  • BA drain is required unless the basement is going to remain unfinished for the life of the building.

    The trigger is a below-grade space that is habitable or usable, not whether the basement gets finished.

  • CNo drain is required, because the exemption covers any lot where the excavation happens to be dry on the day of inspection.

    A dry hole in fair weather is not a soil classification and cannot support the exemption.

  • No drain is required, because the code exempts foundations resting on well-drained ground or on Group I sand and gravel soils.

Why D is correct

The drainage requirement carries an exception for foundations installed on well-drained ground or on sand-gravel mixture soils classified as Group I. With that classification in the soils information for the lot, the omission of drain tile is compliant, and the inspector documents the basis rather than writing a correction.

What this question is testing

Whether the candidate can apply an exception correctly, which means checking that the specific condition named in the code is documented rather than assumed from a field observation.

On the job

This one comes up constantly in sandy coastal and glacial-outwash subdivisions where builders have gone decades without drain tile and are genuinely puzzled by the question. The professional answer is to ask for the document that classifies the soil. If the file has it, the exemption stands and everybody moves on; if nobody can produce it, the drain goes in, because the cost of the pipe and stone is trivial next to the cost of proving the point later.

Memory technique

Group I gravel drains itself; clay needs a pipe.

Exam tip

Exceptions on the exam are usually keyed to a named classification or condition; look for that exact wording in the stem.

Where to look it up

IRC Chapter 4, the foundation drainage section at R405.1, including the exception at the end of the paragraph.

10. One rectangular pad footing measures 24 inches by 30 inches and carries a column load the approved plans give as 7,000 pounds, and the presumptive load-bearing value being used for the site is 1,500 pounds per square foot. Judging the bearing pressure alone, what should the inspector conclude?

  • The pad is adequate, because 5 square feet of bearing area holds the pressure to 1,400 pounds per square foot.
  • BThe pad is inadequate, because 4 square feet of bearing area produces 1,750 pounds per square foot.

    Squaring the short dimension throws away the extra 6 inches of length and understates the bearing area by a full square foot.

  • CThe pad is inadequate, because 7,000 pounds spread across the 2-foot width works out to 3,500 pounds per square foot.

    Dividing a total load by one width gives a load per lineal foot, not a pressure, so it cannot be compared with the soil value.

  • DThe pad is adequate, because a pad at least 24 inches in each direction may be used with any soil listed in the presumptive table.

    No minimum pad size in the code substitutes for a bearing check against the soil value in use.

Why A is correct

Area equals 2.0 feet times 2.5 feet, or 5.0 square feet. Pressure equals 7,000 pounds divided by 5.0 square feet, or 1,400 pounds per square foot, which is below the 1,500 presumptive value. The pad satisfies the bearing check and the inspector can release it.

What this question is testing

Whether the candidate computes area from two different dimensions instead of assuming a square, and keeps the distinction between pressure in pounds per square foot and load in pounds per lineal foot.

On the job

Interior pad footings are often poured before anyone knows what column lands on them, and it is common to find the same size pad used everywhere on a plan that has three different column loads. The check takes fifteen seconds with a tape and the load from the plan. Where the pad is short, the fix before the slab and columns go in is simple: pour a larger pad or add one. After the girder is loaded it is a jacking and underpinning job.

Memory technique

Pressure is load over area, and area needs both sides of the rectangle.

Exam tip

Rectangular pads are worth a second look; the exam expects you to multiply, not to square one side.

Where to look it up

IRC Chapter 4, the footing provisions at R403.1 together with the presumptive load-bearing value table in R401.4.

11. The framing plan notes a design load of 60 pounds per square foot carried over a tributary width of 14 feet at this wall, the footing has been formed 16 inches wide, and the soils information for the lot rates the ground at 1,500 pounds per square foot. What bearing pressure does this footing deliver?

  • A840 pounds per square foot

    This is the line load on the wall in pounds per lineal foot, not the bearing pressure. It is the right intermediate number reported one step too early, and it treats the footing as though it were 12 inches wide.

  • 630 pounds per square foot
  • C1,260 pounds per square foot

    This divides the line load by 8 inches rather than 16, which doubles the answer. It usually comes from using a half width or from mixing up the footing width with the wall thickness.

  • D420 pounds per square foot

    This divides by 24 inches instead of 16. Using a footing width the plans do not show understates the pressure and can hide a genuinely overloaded footing.

Why B is correct

Sixty pounds per square foot over a 14-foot tributary width gives 840 pounds per lineal foot. Dividing by the 16-inch footing width, which is 1.333 feet, gives 630 pounds per square foot, comfortably within the 1,500-pound presumptive value.

What this question is testing

Whether the candidate can convert an area load and tributary width into a line load, then into a bearing pressure using the correct footing width in consistent units, and compare the result against the allowable value.

On the job

Bearing pressure checks come up whenever a house has a long interior span, a heavy point load, or soil weaker than the plans assumed. The tributary width is the piece most often botched: it is half the span on each side of the wall, not the full span. Inspectors who can run this in the field can decide on the spot whether a soil surprise in the trench matters or not, which saves a trip and a stop-work.

Memory technique

Pounds per foot, then pounds per square foot.

Exam tip

Two steps: psf times tributary width gives plf, then divide by the footing width in feet.

Where to look it up

IRC Chapter 4, foundations, footings and the presumptive load-bearing value table, with loads from the approved plans.

12. About twenty minutes into the placement the crew asks the driver to add 15 gallons of water so the mix flows better around the steel, and the ticket describes a 3,000-pound-per-square-inch mix. How should the inspector respond?

  • AAccept it; water added at the site is a normal adjustment and the strength of the mix is set at the plant, not on the job

    The strength is specified at the plant and destroyed at the site. That is exactly why adding water is controlled rather than left to the crew's preference for a mix that flows.

  • BAccept it; the mix will still reach the specified strength provided the crew vibrates the concrete thoroughly after placement

    Vibration consolidates concrete and removes voids, which is a different problem. It does nothing about a water-cement ratio that has already been raised past the design value.

  • Reject the addition; the strength depends on the water-cement ratio, so water beyond the design allowance must not be added
  • DReject the entire load; once any water is added at the site the concrete is no longer the mix the plans specify

    Some water addition is contemplated and permitted within the design allowance, so a blanket rejection of the load overstates the rule. The question is how much water and whether it was within what the mix design held back.

Why C is correct

Concrete strength is controlled by the water-cement ratio. Water within the design allowance held back at batching may be added and documented, but water beyond it lowers strength and cannot be recovered by placement technique. The addition is stopped, and any water already added beyond the allowance calls for evidence that the concrete meets the specified strength.

What this question is testing

Whether the candidate knows what actually controls concrete strength, understands that a limited site water addition is contemplated and documented, and can pick a proportionate response rather than accepting or rejecting wholesale.

On the job

Watery mixes are requested constantly, especially on walls with congested steel or on hot days when the pour is going slowly. Inspectors who watch the truck and the ticket catch it; those who arrive after the pour never will. Where an addition happened, the department can require cylinder tests or a core, which is expensive and slow, and that possibility is usually enough to stop the practice on a job.

Memory technique

Every gallon added is strength poured out.

Exam tip

Water is the enemy of strength. Ask whether the addition was within the design allowance on the ticket.

Where to look it up

IRC Chapter 4, foundations, the concrete materials paragraph and the specified compressive strength table.

13. The trench is 18 inches from the face of the footing and its bottom is 14 inches below the bottom of the footing, and the sewer line is already laid in it. What is the concern the inspector must address?

  • ANone; a trench inside the building line does not affect a footing because the footing is loaded from above rather than from the side

    A footing is supported by a wedge of soil that extends outward as well as downward. Excavating beside it removes part of that wedge, which is why a trench nearby can undermine a footing it never touches.

  • BNone; the concern applies only to trenches that physically undercut the footing, and this trench is clear of it by 18 inches

    Undercutting is the extreme case, but the wedge extends well beyond the footing edge. Judging only by whether the trench touches the footing misses the geometry that governs.

  • The trench removes the soil that supports the footing, since it drops below the plane sloping down and out from the footing edge
  • DThe trench must be at least 24 inches from the footing, which is the fixed clearance required for any parallel excavation

    There is no single fixed clearance dimension, because the answer depends on how deep the trench goes as well as how far away it is. The 45-degree plane relates the two, which a flat number cannot do.

Why C is correct

Load from a footing spreads into the soil at roughly 45 degrees, and a trench that drops below that plane removes the material carrying the load. At 18 inches away and 14 inches below the footing, this trench cuts into the bearing wedge and must be addressed by compacted backfill or underpinning.

What this question is testing

Whether the candidate understands that footing loads spread into the soil at an angle, can apply the 45-degree bearing plane to a measured trench position and depth, and recognizes that no single clearance dimension answers the question.

On the job

Plumbers dig these trenches after the foundation is in and often after the slab is poured, and the trench is usually backfilled and covered before anyone sees it. Inspectors on a plumbing rough in an existing basement look for spoil piles along a wall and ask how deep the trench went. Settlement from this shows up as a crack in the wall above the trench line, sometimes years later.

Memory technique

The footing leans on soil beside it, not just under it.

Exam tip

Picture a 45-degree line down and out from the footing edge. Nothing digs below it.

Where to look it up

IRC Chapter 4, foundations, footing support requirements, read with the excavation and trenching provisions in the plumbing chapters.

14. The approved plan reproduces the plain masonry wall table for this soil: an 8-inch nominal wall to 4 feet of unbalanced backfill, a 10-inch wall to 5 feet, a 12-inch wall to 6 feet. The rear stem wall is 8-inch block with 5 feet 4 inches of unbalanced fill. What is the finding?

  • AAccept it; the table gives values for basement walls, and a crawl space stem wall is not covered by those limits

    The tables apply to foundation walls retaining earth, whether they enclose a basement or a crawl space. The soil pressure does not know what is on the other side of the wall.

  • Reject it; at 5 feet 4 inches of fill the 8-inch wall is past its tabulated limit and needs a thicker wall or a design
  • CAccept it; the 8-inch wall is acceptable once the cores are filled solid with mortar as the mason parges the exterior

    Mortar in the cores is not grout and does not provide the reinforced section a taller wall needs. Parging is a dampproofing step, and neither addresses the bending the wall is being asked to resist.

  • DReject it; unbalanced backfill against a masonry wall is limited to 4 feet in all cases, whatever the wall thickness

    Four feet is the limit for the thinnest wall in the table, not a universal cap. Thicker walls carry more, which is the whole point of a table indexed by thickness.

Why B is correct

The table limits an 8-inch plain masonry wall to 4 feet of unbalanced backfill, and this wall carries 5 feet 4 inches. The remedies are a 12-inch wall, a designed reinforced wall, or regrading to reduce the backfill height. The wall as built is outside the prescriptive provisions.

What this question is testing

Whether the candidate reads a masonry foundation wall table by both thickness and backfill height, applies it to a crawl space stem wall, and knows the available remedies when the table is exceeded.

On the job

Crawl space stem walls on sloping lots are where this appears, because the wall grows tall at one corner while the crew builds the same 8-inch block all the way around. Inspectors measure the fill height at the tallest point rather than at the average, since that is where the wall fails. The failure mode is a horizontal crack along a bed joint at about mid-height, with the wall bowing inward.

Memory technique

Thin block, shallow fill.

Exam tip

Plain masonry walls have short backfill limits. Measure the fill at the tallest point.

Where to look it up

IRC Chapter 4, foundations, the plain masonry foundation wall tables indexed by thickness and unbalanced backfill.

15. Rather than sleeving the pipe, the crew stopped the footing 18 inches short on each side of it, leaving a 3-foot gap in the continuous footing directly beneath an interior bearing wall. How should the inspector judge this?

  • AAccept it; the wall spans the gap easily because a stud wall acts as a deep beam over an opening of that size

    A stud wall is a series of columns bearing on a plate, not a beam. It has no capacity to span an unsupported length, which is why the footing beneath it has to be continuous.

  • BAccept it; the gap is under 4 feet, and short interruptions in a footing are permitted where a pipe crosses

    There is no short-gap allowance in the footing provisions. Pipes cross footings on nearly every job and are handled by sleeving or by thickening the footing, not by leaving it out.

  • Reject it; the footing under a bearing wall is continuous, and bridging a gap of this size requires a designed member
  • DReject it; the pipe must be relocated outside the building, since piping may never cross beneath a footing line

    Piping routinely passes through and beneath footings, and the code contemplates it. Ordering the line relocated outside the building is a far heavier remedy than the situation calls for.

Why C is correct

Footings under bearing walls are continuous so the load spreads along the length of the wall. A 3-foot gap concentrates load on the ends of the remaining footing and leaves the wall unsupported, so it takes a designed member to span it. Sleeving the pipe through the footing is the normal solution.

What this question is testing

Whether the candidate understands why footings under bearing walls are continuous, recognizes that a stud wall cannot span, and knows the ordinary ways a pipe crossing is handled.

On the job

This one hides well: once the slab is poured, the gap is invisible and only shows up years later as a crack in the wall above and a dip in the floor. Inspectors walk the whole trench before the pour, not just the corners, and look specifically where mechanical trades have crossed. Sleeving the pipe takes ten minutes if it is caught before the truck arrives.

Memory technique

No footing, no bearing.

Exam tip

Bearing walls need footing under their whole length. A gap needs a beam.

Where to look it up

IRC Chapter 4, foundations, the general footing provisions covering continuous footings under bearing walls.

52 more in the bank

Answers and explanations for these are in the app.

  • The forms for a continuous concrete wall footing measure 20 inches wide and 5 inches deep beneath an 8-inch foundation wall, and the 20-inch width is adequate for the soil and the load. How should the inspector treat the depth of the forms?
  • The trench bottom measures 40 inches below finished grade, and the contractor intends to place an 8-inch-thick footing in it. Applying the published local frost line of 42 inches, what is the correct inspection result?
  • The completed structure is a freestanding light-frame storage building, 12 feet by 16 feet, with an 8-foot eave height, sitting on thickened-edge footings that stop 16 inches below grade and touching no other structure. What is the correct disposition?
  • One continuous plate section will run 22 feet along a foundation wall. Using half-inch anchor bolts at the code maximum spacing, with a bolt required no more than 12 inches from each end of the plate section, what is the smallest number of bolts that can hold this plate down?
  • Along one wall the half-inch anchor bolts are spaced 5 feet apart and embedded 7 inches into the concrete, but the bolt nearest the end of a plate section sits 20 inches in from that end. What is the correct finding for this wall?
  • A 30-inch-long piece of sill plate sits between a foundation step and a formed opening, and the crew has held it down with a single half-inch anchor bolt centered in its length. Everything else on the wall checks out. What should the inspector do about that short piece?
  • The basement wall encloses finished habitable space, the site is known to have a high water table, and the contractor has brushed on a bituminous dampproofing coating from the footing to grade. How should the inspector treat this exterior treatment?
  • The concrete foundation wall retains about 7 feet of earth and encloses a finished basement, and no drain pipe or drainage stone has been placed at the footing. The contractor says the dampproofing coating makes a drain unnecessary. How should the inspector respond?
  • The perforated drain pipe sits on 2 inches of washed gravel, but the stone above it is only 4 inches deep, stops flush with the outside edge of the footing, and no fabric has been laid over it before backfill. What is the correct call?
  • About 7 feet of soil is already piled against the wall, the first floor framing has not been installed, and no kickers or bracing of any kind are visible inside the basement. What should the inspector do right now?
  • At the rear of the house the landscaper has brought soil up so that the concrete foundation wall stands only 3 inches above the adjacent finished grade for a run of about 20 feet. What is the correct finding?
  • Under the main girder the framer has installed a solid sawn wood column of nominal 3-inch by 4-inch dimensions, resting on a poured pier and carrying two floor loads above. Judging the column itself, what should the inspector do?
  • The installed column is a 2-inch-diameter steel pipe set on the basement slab and welded to a plate under the girder, and no engineering has been submitted for it. What is the correct inspection outcome?
  • One pressure-preservative-treated wood post carrying the girder is set with its bottom end resting directly on the earth of the crawl space floor, with no pier or pedestal under it. How should the inspector treat this post?
  • On the side yard, which is open ground with room to work and no retaining wall or lot line in the way, the finished soil falls only 2 inches over the first 10 feet away from the foundation. What is the correct finding for that side?
  • The trench bottoms are a firm, uniform sandy clay, no soil investigation was made for the lot, and the footing widths on the approved plans were sized using an assumed load-bearing value of 2,000 pounds per square foot. How should the inspector treat that assumed value?
  • The soil report on file describes dense sandy gravel across the entire lot, but along one 25-foot run the trench bottom is a damp soft material that a probe rod pushes into with hand pressure. What is the appropriate response from the inspector?
  • The ascending slope behind the house is steeper than 1 unit vertical in 1 unit horizontal and rises 50 feet above the building pad, and the tape reads 12 feet from the toe of that slope to the face of the foundation wall. What should the inspector require?
  • At one corner the trench was dug roughly 14 inches below the design elevation by mistake, and the crew has pushed the loose spoil back into the hole and tamped it with the excavator bucket to bring the bottom back up to grade. How should the inspector rule on that corner?
  • Along the shaded north side of the excavation the trench bottom carries a frozen crust about 3 inches thick, and the contractor wants to place concrete on it right away because the forecast promises a thaw by afternoon. How should the inspector rule?
  • The locally adopted frost depth is 42 inches. Along the rear wall the trench bottom measures 44 inches below the ground the crew is standing on, and the approved grading plan lowers the finished grade at that wall by 8 inches. What should the inspector conclude?
  • The approved plans call for one row of vertical bars held toward the interior face of a 10-inch concrete wall, but the crew has wired the bars to the form ties so they sit centered in the form, about 5 inches from each face. How should the inspector treat this?
  • Concrete was placed to roughly mid height of an 8-foot basement wall and then stopped for three days, and the surface where the two placements meet is smooth, dusty and shows no keyway, roughening or added dowels. That wall will retain about 6 feet of earth. How should the inspector proceed?
  • Along the front wall the sill plate is held down with 3/8-inch-diameter anchor bolts spaced 4 feet apart, embedded 8 inches into the concrete, each with a nut and washer drawn tight. Judging the anchorage, what should the inspector do?
  • One plate section runs 13 feet 6 inches along the foundation and carries three half-inch anchor bolts, one set 10 inches in from each end of the piece and one at the midpoint, each embedded 7 inches into the concrete. Applying the general spacing and end distance limits, what should the inspector conclude?
  • Rather than half-inch cast-in-place bolts, the crew set galvanized steel straps into the wet concrete and bent them up over the sill plate, and the product carries an evaluation report showing capacity equal to bolts at the spacing installed. How should the inspector treat the substitution?
  • The block foundation encloses an unfinished basement, the site drains well and no high water table has been reported, and the crew has sprayed a bituminous dampproofing coating directly onto the bare block from the top of the footing upward. What should the inspector require?
  • The dampproofing on the outside of the wall begins at the top of the footing and stops roughly 18 inches below the finished grade line marked on the survey stakes, and the contractor explains that the upper part of the wall stays dry anyway. How should the inspector rule?
  • The perforated pipe is bedded in washed stone that extends past the edge of the footing and rises well above the top of the pipe, and the crew is ready to push soil back against the stone with no fabric or other covering laid over it. What should the inspector require?
  • The approved plans show no passive soil gas system, the county sits inside a zone the federal maps rate as high radon potential, and the jurisdiction adopted the residential code without adopting its radon control appendix. How should the inspector answer the builder?
  • The crew has adhered rigid foam plastic board to the outside face of the concrete foundation wall, carrying it from the sill down about 4 feet below finished grade, and the wall above supports conventional wood framing. What should the inspector do?
  • The bottom plates of the exterior walls rest directly on the concrete slab, which bears on the ground, and the plates carry no preservative treatment stamp and no sill sealer or other barrier beneath them. How should the inspector rule?
  • The material going back against the wall is excavated spoil mixed with broken form lumber, chunks of scrap concrete and frozen clods the size of a five-gallon bucket, and the operator is dropping it in full-height lifts straight down the face of the wall. What should the inspector do?
  • The soil along that wall is far softer than the design assumed, and the contractor produces a manufacturer catalog with capacity tables for a proprietary helical pier system and asks you to release the change so the crew can start installing this afternoon. What is the correct path?
  • The approved plans show the main girder delivering 1,150 pounds for every lineal foot it carries, and they rate each masonry pier with its footing at 9,200 pounds. The crew has set the piers 10 feet apart on center along the girder line. What should the inspector conclude?
  • The studs and plywood in the below-grade wall carry a treatment stamp for above-ground use, and the walls are fastened with hot-dipped galvanized nails. What is the correct finding?
  • The anchor bolts have been dropped into open cores of the top course with no grout around them, and the cores below are open to the bottom of the wall. How should the inspector judge this anchorage?
  • The longitudinal bars have been supported on broken brick so that about 1 inch of space remains between the steel and the earth beneath it. What cover does the code require in this location?
  • The wall stands 9 feet 0 inches from the top of the footing to the top of the wall, the finished exterior grade will be 1 foot 8 inches below the top of the wall, and the basement floor surface is 8 inches above the top of the footing. What is the height of unbalanced backfill?
  • Along the downhill wall the ground on the uphill side of the trench stands 12 inches higher than the ground on the downhill side, and the trench bottom measures 42 inches below the uphill grade. How does this footing stand against the required depth?
  • The plans give a 12,000-pound total load at the column and the soils information for the lot gives a presumptive load-bearing value of 2,000 pounds per square foot. What is the smallest square footing that will carry it?
  • The plans reproduce the footing width table for the 2,000-pound-per-square-foot soil on this lot: light-frame two stories, 15 inches; light-frame two stories with brick veneer, 21 inches. The formed footing measures 16 inches wide. What is the finding?
  • For about 12 feet the trench bottom is sound bedrock and the rest of that wall bears on firm sandy clay, with the change occurring abruptly over roughly a foot. How should the inspector judge this bearing surface?
  • The trench along the low side of the house is entirely in placed fill roughly 5 feet deep, and the contractor says the fill has had a full winter to settle. How should the inspector proceed?
  • The trench sides are sloughing as you watch, sand has run into the bottom in several places, and the trench width varies from 18 to 26 inches along its length. How should the inspector judge this proposal?
  • The crew has sprayed a bituminous dampproofing coating directly onto the block face from the footing to the grade line, over the bare units and mortar joints. What is the correct finding?
  • Over one 5-foot length the trench bottom drops 8 inches and the crew intends to place that stretch as a ramp rather than stepping it. How should the inspector judge that?
  • The crew has framed a 4-foot-wide buck for a future walkout door in a wall carrying two stories, with the wall reinforcement simply cut at the opening and nothing added above it. How should the inspector proceed?
  • The perforated pipe is correctly bedded in washed stone all the way around, and at the northeast corner it turns and discharges through the stem wall onto the crawl space grade under the adjoining wing. What is the correct finding?
  • The footing was left uncovered overnight, and this morning the top surface is frozen, crumbles under a screwdriver and shows ice crystals in the paste. How should the inspector respond?
  • The crew has formed the concrete foundation wall 6 inches thick beneath that 8-inch masonry wall, and the plans show no ledge or corbel at the top of the foundation. What is the correct finding?
  • The approved plans give a total load of 2,500 pounds coming down each deck post, and the soils information for the site gives a presumptive load-bearing value of 1,500 pounds per square foot. The crew has set 16-inch-diameter tubes. What is the finding?

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