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Floor Construction — ICC B1 Practice Questions

62 questions · 14% of the ICC B1 exam

Worked questions

1. The crew laid the polyethylene vapor retarder directly on the subgrade and then spread the 4-inch base course of gravel over the top of it, and the sheets are butted edge to edge without any overlap. What is the correct call?

  • AApprove it, because the sheet is present somewhere in the assembly and its exact position within that assembly is left to builder preference alone.

    Position is the whole point of the requirement. Under the base course the sheet stops nothing, because water vapor moves up through the gravel and reaches the underside of the slab from the stone itself.

  • BApprove it, because the gravel placed above the sheet protects it from being punctured during the placement of the concrete.

    Puncture resistance is a construction convenience rather than the code's concern. Burying the retarder beneath the stone protects the sheet at the cost of the one function it was installed to perform.

  • Reject it, because the vapor retarder belongs directly beneath the slab on top of the base course, with joints lapped not less than 6 inches.
  • DReject it, because a vapor retarder is required under every concrete slab on every site, with no exceptions available at all.

    The code carries exceptions, among them unheated garages, utility buildings and slabs approved for such use. A rule stated with no exceptions is easy to disprove and weakens an otherwise correct correction.

Why C is correct

Position and lap are both prescribed: the vapor retarder goes between the base course and the slab, and joints lap not less than 6 inches. A sheet buried under the gravel allows the base to become saturated and deliver moisture to the underside of the concrete, while butted seams pass vapor freely. The correction is to lift and relay the sheet on top of the leveled base with lapped joints before concrete is placed.

What this question is testing

Whether the candidate knows where in the assembly the vapor retarder belongs and the joint treatment required, and whether they remember that the requirement carries exceptions rather than applying to every slab on every site.

On the job

You will hear that burying the sheet keeps the concrete from curling, and there is a real construction argument behind that, but it is not the code path and it puts the retarder where it cannot work. Look for lapped seams, sheets carried up to the edge forms, and penetrations at plumbing sleeves taped rather than left torn. Once the slab is placed the condition is permanent and the symptom, years later, is flooring adhesive failure that nobody connects back to this morning.

Memory technique

Plastic goes last before the concrete, and every seam gets a six-inch handshake.

Exam tip

Order of layers matters: subgrade, base course, vapor retarder, then concrete.

Where to look it up

IRC Chapter 5, concrete floors on ground, the vapor retarder subsection with its exceptions for unheated and exterior slabs.

2. The three-ply built-up girder is made from 2 by 10 material, and in one bay the butt joints of two of the three plies land together roughly 3 feet from the nearest pier, out in the middle of the span. How should the inspector rule?

  • AApprove it, because nailing the plies tightly together transfers load across any joint in the members, so the two continuous plies carry the broken one past the joint between the piers.

    Nails hold the plies side by side and share vertical load between them, but they cannot carry bending across the end grain of a butt joint. The interrupted ply contributes nothing at midspan.

  • BApprove it, because only the outer plies of a built-up girder have to run continuous between supports, and both of the outer plies are unbroken in this bay.

    All plies count toward the capacity of a built-up girder, so a break in an interior ply is just as much a loss of section as a break in an outer one, and here two of the three are broken together.

  • CApprove it if the joint is covered with a plywood scab nailed to both faces of the girder, which splices the interrupted plies back to their full section again.

    A scab may be part of an engineered repair, but choosing its size, material and nailing in the field substitutes for the design nobody has done. The prescriptive answer is to move the joints over a pier.

  • Write a correction, because butt joints in the plies belong over a support, and stacking two of them away from a pier leaves the girder short of section where it is bending hardest.

Why D is correct

Joints in the plies of a built-up girder are made over supports, where bending is minimal, and are staggered between plies. Two joints stacked at the same point 3 feet out into a span leave only one ply continuous through the section carrying the most bending, so the girder has to be rebuilt or the joints relocated.

What this question is testing

Whether the candidate understands how a multi-ply member develops capacity and can identify the correct joint location by reasoning about where bending is greatest and least.

On the job

Built-up girders are cut from whatever lengths came off the truck, and joints migrate toward the middle of a bay when a crew is trying to avoid waste. Sight down the girder and mark every joint, then check that each one lands over a pier and that no two align. Correcting it while the girder sits on open piers is a matter of sliding members; correcting it after the floor is loaded means shoring the whole line.

Memory technique

Joints belong over piers, never over air.

Exam tip

For any multi-ply beam question, ask where bending is smallest; that is where the code puts the joints.

Where to look it up

IRC Chapter 5, the girder and beam provisions in R502 together with the built-up girder details and their span tables.

3. The soils information for the lot classifies the ground as a well-drained sand and gravel mixture in Group I, and the crew intends to place the concrete floor slab directly on the prepared subgrade with no 4-inch course of clean graded stone beneath it. What should the inspector conclude?

  • AA base course is required, because every slab on ground has to be placed over 4 inches of clean graded material with no exception available.

    The 4-inch base course is the general rule and it carries an exception. Reading the requirement as absolute makes the inspector call for fill on a site where the code already accepts the natural soil as a capillary break.

  • BA base course is required here, and the code allows it to be omitted only where the finished slab will carry vehicle traffic.

    Vehicle traffic is not a variable anywhere in this section; the exception turns on the soil beneath the slab. Bringing in the loading is a garage-slab instinct that has nothing to do with why the base course is there.

  • No base course is required, because the code waives it where the slab sits on well-drained ground or on Group I sand and gravel soils.
  • DNo base course is required, because the vapor retarder placed under the slab serves exactly the same purpose as the gravel.

    The base course and the vapor retarder do different jobs. The gravel breaks capillary rise and gives the retarder a level bed, while the sheet stops vapor diffusion, and neither one substitutes for the other.

Why C is correct

The base course requirement carries an exception where the slab is placed on well-drained ground or on sand and gravel mixture soils classified as Group I. With that classification documented for the lot, placing the slab on the prepared subgrade is compliant and the inspector records the basis.

What this question is testing

Whether the candidate can find and apply an exception tied to a named soil classification, and keeps the base course and the vapor retarder as separate requirements rather than interchangeable ones.

On the job

Sandy regions have entire subdivisions built without a stone base, and inspectors there field this question constantly. The professional habit is the same as with the drainage exemption: ask for the document that classifies the soil. When the classification exists the exception is legitimate and well established; when nobody can produce it, four inches of stone is far cheaper than the argument.

Memory technique

If the ground is already gravel, you do not need to buy gravel.

Exam tip

Group I soils turn up in two exceptions, foundation drains and slab base course; recognize the phrase.

Where to look it up

IRC Chapter 5, the concrete slab-on-ground provisions at R506.2, including the base course paragraph and its exception.

4. Under the slab the crew has spread 4-mil polyethylene sheeting over the base course with the seams butted edge to edge and no overlap, and the sheeting is cut oversize around the plumbing penetrations. What should the inspector require before concrete is placed?

  • ANothing further, because polyethylene sheeting of any thickness is accepted as a vapor retarder beneath a slab.

    A minimum thickness is specified, and thin film also tears under traffic before the concrete arrives.

  • BThat the sheeting be removed, because a vapor retarder laid over the base course rather than under it traps water in the stone.

    The retarder belongs between the slab and the base course, so its position here is already correct.

  • CThat a second layer of the same 4-mil sheeting be laid at right angles to the first to make up the thickness.

    Two thin layers do not equal one of specified thickness, and the code names a material, not a sum.

  • A vapor retarder of at least 6-mil polyethylene or an approved equivalent, with joints lapped not less than 6 inches.

Why D is correct

The under-slab vapor retarder must be at least 6-mil polyethylene or an approved equivalent, with joints lapped not less than 6 inches. The 4-mil sheeting with butted seams meets neither condition, so it has to be replaced or overlaid with compliant material before the pour.

What this question is testing

Whether the candidate recalls both halves of the vapor retarder requirement, material thickness and joint lap, and can distinguish it from the separate requirement for a base course beneath the slab.

On the job

This is a five-minute inspection that pays for itself in flooring callbacks. Walk the slab area looking for the roll stamp, which prints the mil thickness right on the film, then look at the seams and at the penetrations. Damaged sheeting is normal by the time the reinforcement is set, so expect to ask for taping and patching. Remember the exception for unheated accessory buildings and exterior flatwork, which is why a detached garage slab may be poured without one.

Memory technique

Six and six: six mil thick, six inches lapped.

Exam tip

Six mil and six inches: the two numbers travel together in this provision.

Where to look it up

IRC Chapter 5, the vapor retarder paragraph under the concrete slab-on-ground provisions at R506.2.

5. The exposed ground is covered with a sealed vapor retarder that laps up and is fastened to the stem walls, the perimeter walls are insulated, no wall ventilation openings were installed, and there is no mechanical exhaust from the space and no supply of conditioned air into it. How should the inspector rule?

  • AApprove it, because a continuous sealed ground cover carried up and fastened to the stem walls is by itself what qualifies a crawl space as unvented under this code.

    The ground cover is half of the unvented package. The other half is a mechanism that keeps air moving and dry, and without it the sealed space simply holds whatever moisture reaches it.

  • Write a correction, because an unvented crawl space also needs an air change method, either continuously operating exhaust or a supply of conditioned air sized to its floor area.
  • CApprove it, because insulating the perimeter walls of the space takes the place of the air change that the unvented crawl space option would otherwise require.

    Insulation is part of the exhaust-fan option rather than a substitute for it. Perimeter insulation changes the temperature in the space but moves no air, so the moisture still has nowhere to go.

  • DWrite a correction requiring ventilation openings to be cut through the stem walls, because a crawl space built with no wall vents at all is not a condition that the code permits.

    The unvented crawl space is a recognized option, so demanding wall vents rejects an assembly the code allows. The missing item is the air change method, not the vents that option trades away.

Why B is correct

An unvented crawl space requires both a sealed ground vapor retarder lapped up the walls and one of the listed air change methods, such as continuously operating exhaust with insulated perimeter walls or a supply of conditioned air sized to the floor area. Without either mechanism the space is incomplete and a correction is warranted.

What this question is testing

Whether the candidate knows that the unvented crawl space option is a package with two required halves, and can identify which listed method the installation was attempting to satisfy.

On the job

Sealed crawl spaces are now the default in humid regions and they work extremely well when finished, but the fan or the supply register is the piece most often left off, usually because it belongs to a different trade than the one who sealed the ground. On a final inspection, find the mechanical component before you look at anything else: a running exhaust fan, a duct with a damper, or a dehumidifier with a condensate line. If nothing is moving air, the assembly is not done.

Memory technique

Seal the ground and move the air; one without the other is a wet box.

Exam tip

Sealed ground cover plus an air change method: if the stem gives you only one, the answer is a correction.

Where to look it up

IRC Chapter 4, the unvented crawl space provisions at R408.3 and the list of acceptable air change methods.

6. One 2x10 joist carries a split running about 14 inches in from its bearing end, straight along the grain at mid-depth, wide enough to pass a fingernail. How should the inspector handle this member?

  • AAccept it; a split in the end of a joist is closed by the bearing pressure and has no effect on how it carries load

    Bearing pressure acts vertically at the support and does not close a horizontal split along the grain. The split remains a plane of separation through the depth of the member.

  • BAccept it; the grade stamp on the joist governs, and a member that carries a stamp has already been judged acceptable

    A grade stamp records the condition of the piece at the mill. Damage from handling, storage or weather afterward is the inspector's to judge, and it is not covered by the stamp.

  • Reject the member; a split at the bearing end reduces shear capacity where shear is highest, so it must be replaced or reinforced
  • DReject the member; every joist showing any check or split has to be replaced, since visible defects are not permitted in framing lumber

    Checks and small surface splits are normal in seasoned lumber and are contemplated in the grading rules. Rejecting every visible defect would condemn most of the lumber on any job and is not what the code asks.

Why C is correct

Shear is highest at the supports, and a split along the grain at mid-depth separates the member on the plane where that shear acts. A 14-inch split at the bearing end therefore removes capacity where the joist needs it most, and the member is replaced or reinforced with an approved detail.

What this question is testing

Whether the candidate can judge a material defect on its own merits, relates the location of the defect to where shear governs, and distinguishes damage from the normal seasoning characteristics the grading rules already allow.

On the job

Splits at bearing ends come from lumber dropped off a truck, from banding that was cut while the bundle was stacked badly, and from joists left in the weather and then dried quickly. Inspectors look at the ends of members over supports, where a split does the most harm, and use a knife or a fingernail to judge depth. The repair is usually a full-depth scab or a hanger, which is cheap compared with replacing a joist under a finished floor.

Memory technique

Shear lives at the ends; keep the ends whole.

Exam tip

Where the defect sits matters as much as its size. Splits at supports attack shear.

Where to look it up

IRC Chapter 5, floors, the general requirements for lumber quality and identification.

7. Each vent is rated at 50 square inches of net free area. No ground cover will be installed, so the ratio is 1 square foot of net free ventilating area for each 150 square feet of under-floor area. What is the largest under-floor area those eight vents may ventilate?

  • About 417 square feet, since 400 square inches is 2.78 square feet and that times 150 gives 417
  • BAbout 833 square feet, applying 1 square foot of net free area for each 300 square feet

    The 1-to-300 ratio belongs to attic ventilation, not to under-floor spaces. Borrowing it here doubles the area the vents appear to cover.

  • CAbout 4,167 square feet, applying 1 square foot of net free area for each 1,500 square feet

    The 1-to-1,500 ratio applies only where an approved ground cover is installed, and the problem says there will not be one. It is the right number for the wrong condition.

  • DAbout 60,000 square feet, since 400 square inches of vent multiplied by 150 gives 60,000

    Multiplying square inches by 150 skips the conversion to square feet and inflates the result by a factor of 144. The size of the answer is the tell: no crawl space covers 60,000 square feet.

Why A is correct

Eight vents give 400 square inches, which is 2.78 square feet of net free area. At 1 square foot for each 150 square feet of under-floor space, that serves 2.78 times 150, or about 417 square feet.

What this question is testing

Whether the candidate converts vent ratings to square feet before applying the ratio, selects the ratio matching the stated ground cover condition, and recognizes an answer that is off by the conversion factor.

On the job

Working the requirement backwards is how a builder decides how many vents to buy, and how an inspector sanity-checks a crawl space at a glance. The habit worth keeping is converting to square feet before touching the ratio, because vent ratings come in square inches and every ratio in the ventilation provisions is square feet to square feet.

Memory technique

Square inches over 144, then times the ratio.

Exam tip

Convert first, then apply the ratio. Both sides of the ratio are square feet.

Where to look it up

IRC Chapter 4, under-floor space, the required ventilating area.

8. The under-floor space measures 1,750 square feet, the sheeting covers about 60 percent of the ground with the remaining 40 percent left exposed, and the installed vents total 240 square inches of net free area. The ratio is 1 square foot of net free area for each 150 square feet of under-floor area, or 1 square foot for each 1,500 square feet where the exposed ground is covered. What is the finding?

  • AIt complies, because the reduced ratio calls for 168 square inches and 240 square inches are installed

    This is the builder's position and it assumes the reduction has been earned. The sheeting has to cover the exposed ground, and a roll laid down the middle of the crawl leaves the perimeter soil evaporating into the space.

  • It requires 1,680 square inches, because the reduced ratio is available only where the exposed ground is covered
  • CIt requires about 773 square inches, prorating the covered portion and the exposed portion of the ground

    Prorating is arithmetically tidy and has no basis in the provision. The reduced ratio is switched on by a condition being satisfied, not blended in proportion to how much of the ground was covered.

  • DIt requires 840 square inches, applying 1 square foot of net free area for each 300 square feet

    One square foot for each 300 is the attic reduced ratio. It has no application to an under-floor space, where the two figures are 150 and 1,500.

Why B is correct

The reduction depends on the exposed ground being covered, and it is a condition rather than a proportion. With bare soil over 40 percent of the space the full ratio applies, requiring 1,750 divided by 150, or 11.67 square feet, which is 1,680 square inches of net free area.

What this question is testing

Whether the candidate treats the reduced ratio as a condition to be satisfied rather than a proportion, and computes the full requirement when the condition fails.

On the job

Partial ground cover is extremely common, usually because the sheeting was laid before the plumber and the electrician finished crawling around under there. The judgment is whether the exposed ground is covered, and the honest answer at a perimeter full of bare soil is no. Builders push back because the vent count is so different, which is exactly the point: the cover is doing the work the vents would otherwise have to do.

Memory technique

Cover all the dirt or count all the vents.

Exam tip

Ratios switch on conditions. Partly satisfied is not satisfied.

Where to look it up

IRC Chapter 4, under-floor space, ventilation and the ground cover condition.

54 more in the bank

Answers and explanations for these are in the app.

  • Walking the deck you find that roughly a third of the floor joists carry no grade mark of any kind, and the superintendent tells you the lumber yard sold them as number two material and the framer eyeballed each piece before installing it. How should the inspector proceed?
  • Measuring several joist ends, you find they lap the plate by only 1 inch before stopping, though each one is toenailed with three nails and the rim joist is fastened across the ends. What is the correct finding?
  • At the interior girder the joists lap and are toenailed to the girder, and nothing else has been installed at that support: no blocking between the joists, no header, and no continuous member across the ends. How should the inspector treat this support condition?
  • In a solid sawn 2 by 10 floor joist with an actual depth of 9.25 inches spanning 15 feet, the plumber cut a 3-inch-deep notch into the top edge at a point 3 feet from the bearing wall. How should the inspector judge that notch?
  • In a solid sawn 2 by 10 joist with an actual depth of 9.25 inches, the electrician bored a 3-inch-diameter hole near midspan, and the edge of the hole is 1.5 inches from the bottom edge of the joist. What is the correct call on this hole?
  • To clear a condensate line, the installer cut a 2-inch-deep notch into the bottom flange of one I-joist, and the manufacturer installation guide on site shows permitted hole locations in the web only. What should the inspector do?
  • To get the duct through, a mechanical installer cut one diagonal web member out of a floor truss and left the chord ends untouched. No documentation about the alteration is on the job site. What is the correct inspection action?
  • For the species, grade, spacing and live load shown on the plans, the span table row permits a maximum clear span of 16 feet 5 inches. On the deck you measure 17 feet 2 inches of clear distance between the inside face of the foundation sill and the face of the center girder. What is the correct finding?
  • The opening is framed with a single header joist spanning 7 feet, end nailed with three nails into a single trimmer joist on each side, with no hangers or framing anchors anywhere at the opening. What is the correct finding?
  • The bottom of the untreated Douglas fir floor joists measures 14 inches above the exposed ground, and the bottom of the untreated girders measures 10 inches above it. No ground cover has been installed yet. What is the correct finding?
  • Measurements at the control joints show the concrete floor slab of a habitable room is a consistent 3 inches thick, and the contractor points out that welded wire reinforcement was placed in the pour. What is the correct finding?
  • The subgrade has been graded and rolled, the plumbing rough is in, and the crew intends to place the floor slab directly on the compacted clay with no granular material beneath it. How should the inspector treat the subgrade?
  • The wood structural panels have been laid with their long dimension running the same direction as the joists, and several panel ends stop between joists with nothing under the joint. How should the inspector treat the deck?
  • The subfloor is single-layer wood structural panel with square cut edges, and the joints running parallel to the joists have no blocking beneath them and no underlayment or topping is planned. What is the correct finding?
  • The 23/32-inch subfloor panels are fastened with 8d nails spaced about 12 inches apart along the supported panel edges and about 24 inches apart over the intermediate joists, and the crew applied construction adhesive under every panel. What is the correct finding?
  • The under-floor space measures 1,500 square feet and the dwelling above it has 1,000 square feet of floor area. Using the requirement of 1 square foot of net free ventilating area for each 150 square feet of under-floor space, what total net free ventilating area does this crawl space need?
  • The under-floor space measures 1,800 square feet. Because the ground cover and corner openings are in place, the required ventilating area may be figured at 1 square foot for each 1,500 square feet of under-floor area. What net free ventilating area does this crawl space need?
  • The exposed ground is covered with polyethylene sheeting laid loose with open seams and stopping about a foot short of the stem walls, and there is no mechanical exhaust or conditioned air supply serving the space. What should the inspector do?
  • The rough opening for the hatch measures 16 inches by 24 inches, and no other access into the under-floor space exists anywhere on the building. What is the correct finding?
  • Where the runs meet, the joists coming from opposite sides lap past one another by 1-1/2 inches on top of the girder and are fastened to each other with two 8d nails, and no splice plate, strap or other connection has been added. How should the inspector rule?
  • The joist ends sit on that concrete ledge with 2 inches of bearing, no hangers have been used, and there is no ribbon strip or other support beneath the joists. How should the inspector rule?
  • Every hanger is the model and size the manufacturer specifies for these joists, but the installer drove 1-1/4-inch roofing nails through the hanger flanges and left roughly a third of the nail holes empty. How should the inspector rule?
  • The span table row on the approved plans permits a maximum clear span of 15 feet 0 inches for these joists. On site the distance from the inside face of the foundation wall to the near face of the girder measures 14 feet 9 inches, the joists lap 4 feet over the girder so each piece is 18 feet 9 inches long, and the distance from the center of one bearing to the center of the other reads 15 feet 1 inch. What should the inspector conclude?
  • The plans show 2 by 10 joists at 16 inches on center, but the joists went in at 19.2 inches on center. For this species, grade and load the span table rows printed on the plans read 15 feet 5 inches at 16 inches on center, 14 feet 6 inches at 19.2 inches, and 13 feet 6 inches at 24 inches, and the clear span measured on site is 14 feet 10 inches. What should the inspector conclude?
  • At the support the framer cut a notch 3-1/2 inches deep into the top of solid sawn 2 by 12 joists whose actual depth is 11-1/4 inches, so that the joists could sit down over the beam. Judging that notch, what should the inspector conclude?
  • The manufacturer hole chart posted on the job allows a 3-inch round hole in the web of these I-joists no closer than 3 feet from the face of a support at the span installed, and the plumber cut a 3-inch hole 20 inches from the face of the beam. What should the inspector conclude?
  • A second-story bearing wall lands over the rim area of the I-joist floor, the manufacturer detail for that condition calls for squash blocks set beside each joist under the load, and none have been installed anywhere along the wall. How should the inspector rule?
  • The approved plan detail permits these joists to cantilever no more than one quarter of their back span, the back span from the exterior wall in to the first interior bearing measures 11 feet 4 inches, the joists are 15 feet 4 inches long overall, and the overhang as built measures 3 feet 6 inches. What should the inspector conclude?
  • The garage ceiling below that bedroom is covered with 1/2-inch regular gypsum board, taped and ready for texture, and the garage walls carry the same material. Judging the ceiling assembly, what should the inspector do?
  • The floor panels carry a span rating stamp reading 32/16, the joists beneath them are laid out at 24 inches on center, and the panels have tongue-and-groove edges with adhesive applied at every joist. Judging the panel rating, what should the inspector conclude?
  • The deck ledger is attached to the band joist of the house with 3-inch deck screws driven roughly every 8 inches in a single row, and the builder points out that the number of screws used far exceeds the number of lag screws the fastener table would have required. How should the inspector rule?
  • The deck ledger has been lag screwed through the brick veneer into the framing behind it, the builder used longer lags to reach the band joist, and no flashing has been installed above the ledger. How should the inspector rule?
  • The ledger is a single 12-foot length of 2 by 10 attached to the band joist of the house, the fastener table row for this joist span gives half-inch lag screws at a maximum of 16 inches on center, and fasteners have to begin at least 2 inches in from each end of the ledger. What is the smallest number of lag screws that satisfies the spacing?
  • The welded wire reinforcement is lying flat on the vapor retarder across the entire pour area, no chairs or other supports are in place, and the foreman tells you the crew will hook the mesh up with a rake as the concrete comes down. How should the inspector rule?
  • The ground inside the crawl space has been dug down below the bottom of the footings so a homeowner could store boxes there, water is standing in two low areas near the center, and no drainage system has been provided anywhere in the space. How should the inspector rule?
  • The under-floor space measures 1,200 square feet, the ratio that applies without a ground vapor retarder is 1 square foot of net free area for every 150 square feet of space, and each louvered and screened vent the builder is using provides 50 square inches of net free area. What is the smallest number of vents that meets the requirement?
  • You measure 2 inches of bearing where the built-up girder sits on the concrete shelf in each pocket, and nothing else supports the ends. What is the correct finding?
  • The plies are fastened with 16d nails driven in a single row along the centerline of the member at about 24 inches on center, with no nails within a foot of either end and none at the splices. How should the inspector judge this fastening?
  • The criteria sheet gives a live load deflection limit for floors of the span divided by 360, and the joists in question have a clear span of 15 feet 0 inches. What is the greatest computed live load deflection this limit allows?
  • The girder runs down the middle of the basement. Joists span 14 feet clear from the front foundation wall to the girder, and 12 feet clear from the girder to the rear wall. What tributary width does this girder carry?
  • The under-floor space measures 1,800 square feet, the applicable ratio is 1 square foot of net free ventilating area for each 150 square feet of under-floor area, and each vent is rated at 50 square inches of net free area. How many vents are required?
  • The plans specify 2x10 joists of a given species and grade at 16 inches on center, and the framer installed the same 2x10 material at 12 inches on center throughout. How should the inspector treat this deviation?
  • The plans show the garage as unheated, with no plumbing under the slab and no habitable space now or later, and the builder asks whether the vapor retarder can be omitted. How should the inspector answer?
  • The approved plans specify No. 2 grade joists of a stated species, and every joist in the floor is stamped No. 3 of the same species at the spacing and span the plans show. How should the inspector judge this?
  • The 2x10 floor joists have an actual depth of 9 1/4 inches, and the bearing partition on the floor above runs parallel to the joists and sits 12 inches to one side of the girder beneath. What is the permitted offset, and does this framing comply?
  • The table row for this species, grade, spacing and load gives maximum clear spans of 13 feet 1 inch for a 2x8, 16 feet 5 inches for a 2x10 and 19 feet 11 inches for a 2x12, all at 16 inches on center. The clear span measured is 15 feet 2 inches. What is the smallest joist that works?
  • The trenches have been backfilled with the spoil that came out of them, dumped loose and raked level with no compaction, and the crew is ready to place the slab this afternoon. How should the inspector respond?
  • The plans show sawn 2x10 joists at 16 inches on center, and the framer installed wood I-joists of the same depth at the same spacing with no revised documents and no manufacturer literature on site. How should the inspector proceed?
  • The joists are 2x10 members 9 1/4 inches deep, and the installer used hangers sized for a 2x8, so the top of each joist stands about 2 inches above the top of the hanger. What is the correct finding?
  • Each floor joist is toenailed to the sill plate with two 8d nails, one from each side, and the rim joist is nailed to the ends of the joists. What does the fastening schedule require at the joist-to-sill connection?
  • The truss design drawings call for continuous strongback bracing through the webs at specified intervals, and none of it has been installed although the subfloor is already down. How should the inspector judge this?
  • The I-joists sit on the sill with nothing between them at the ends: no rim board, no blocking panels and no web stiffeners, and the wall above will bear on this line. What is the correct finding?
  • The under-floor space measures 1,650 square feet. Because an approved ground cover of Class I vapor retarder material is installed with lapped and sealed joints, the ventilating area may be figured at 1 square foot for each 1,500 square feet of under-floor area. Each foundation vent the builder is using is rated at 50 square inches of net free area, and the code also calls for a ventilating opening within 3 feet of each corner of the building. How many vents does this space require?
  • The under-floor space measures 2,200 square feet and the builder is taking the unvented route: the exposed ground carries a sealed vapor retarder lapped up the stem walls and the perimeter is insulated. He proposes continuously operated mechanical exhaust ventilation at a rate of 1 cubic foot per minute for each 50 square feet of crawl space floor area. What rate does this space require?

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