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Roof & Ceiling Construction — ICC B1 Practice Questions

62 questions · 14% of the ICC B1 exam

Worked questions

1. A vented attic of 2,400 square feet is served by continuous soffit vents rated at 1,200 square inches of net free area and a ridge vent rated at 900 square inches. Using the base requirement of 1 square foot of ventilating area for each 150 square feet of ventilated space, how does the installation measure up?

  • It falls short: 16 square feet, or 2,304 square inches, is required and only 2,100 square inches has been provided.
  • BIt complies, because the installed total comfortably exceeds the 8 square feet the code requires for this attic.

    Eight square feet comes from the reduced ratio, which nothing in this installation establishes.

  • CIt complies, because net free ventilating area has to be provided only at the ridge.

    Exhaust at the ridge without intake at the eaves does not ventilate an attic and is not how the area is counted.

  • DIt falls short, because one square inch of net free area is needed for each square foot of attic, which is 2,400 square inches.

    Treating the ratio as one square inch per square foot mixes units and understates the requirement.

Why A is correct

The base ratio is one part in one hundred fifty applied to the ventilated area: 2,400 divided by 150 equals 16 square feet, which is 2,304 square inches. The installed products supply 2,100 square inches of net free area, leaving the attic roughly 204 square inches short. The correction is more net free area, and it is far easier to add soffit venting or extend the ridge vent before the roof covering is finished.

What this question is testing

Whether the candidate can convert a ventilation ratio into square inches and compare it against the net free area published for real products, and whether they resist both the reduced ratio and the units error that the wrong choices offer.

On the job

Net free area is the number that matters and it is always smaller than the hole. Ask for the product data sheets rather than measuring openings, because a perforated soffit panel or a baffled ridge vent delivers a fraction of what its size suggests. Add up intake and exhaust separately as well, since a roof with plenty of ridge vent and blocked soffits fails in service even when the arithmetic works on paper.

Memory technique

One in one fifty, then times one forty-four: the answer lives in square inches on the job.

Exam tip

Convert square feet to square inches by multiplying by 144 before comparing against vent product ratings.

Where to look it up

IRC Chapter 8, roof ventilation, where the base ratio and the conditions for the reduced ratio appear together.

2. The insulation contractor laid batts between the ceiling joists and then rolled a continuous polyethylene sheet over the top of the insulation, on the attic side of the assembly. How should the inspector treat this installation?

  • AApprove it, because a vapor retarder performs the same on either face of the insulation as long as the sheet is continuous and well sealed at its laps.

    Position is the whole point of a retarder. On the attic side it lets vapor pass up through the insulation and condense on the underside of the cold sheet, wetting the insulation from above.

  • BApprove it, because the sheet also keeps the loose insulation from being disturbed by air moving through the attic space, which improves the assembly overall.

    Holding insulation in place is not a code function, and these batts sit between joists already. The placement of the sheet is what fails, and a benefit elsewhere does not cure a retarder on the cold side.

  • Reject it, because a required vapor retarder belongs on the side of the assembly that is warm in winter, meaning under the insulation against the ceiling.
  • DReject it, because a vapor retarder is prohibited in a vented ceiling assembly in every climate zone the code recognizes, so the sheet has to come out.

    Ceiling vapor retarders are required in the colder zones rather than prohibited. This reaches the right disposition through a rule that does not exist, and it would leave the assembly with no retarder at all.

Why C is correct

Where the code requires a vapor retarder in an assembly, it goes on the side that is warm during the heating season, which for a ceiling in a cold climate is the interior face beneath the insulation. Installed on the attic side, the sheet becomes the coldest surface in the assembly and vapor condenses against it. The correction is to remove the sheet or to rebuild the assembly with the retarder against the ceiling.

What this question is testing

Whether the candidate can apply the underlying principle of vapor retarder placement rather than reciting a table, and understands why the wrong side is worse than none at all. It also tests recognizing that the requirement is climate-zone driven rather than universal.

On the job

Poly over the top of attic insulation is a classic do-it-yourself and small-remodel mistake, often done with the honest belief that it is an air barrier. You will also see it in an attic where someone laid plastic before decking part of the floor for storage. Since climate zone drives what is required, check the zone the jurisdiction sits in and the plans before writing the correction, and be prepared to explain the physics, because the argument on site is always that plastic is plastic.

Memory technique

The retarder faces the people, not the weather.

Exam tip

Warm in winter is the phrase to hold onto; in a heating climate that is the room side of the insulation.

Where to look it up

IRC Chapter 7 for vapor retarder classes and the climate zones where each is required, together with the energy provisions for ceilings. Check the zone your jurisdiction has adopted.

3. The panel stamp shows a roof span rating that permits these panels over supports spaced 24 inches on center provided the unsupported edges are supported, the trusses are set at 24 inches on center, and the long edges between panel rows have no clips, no tongue-and-groove joint and no blocking. What is the correct finding?

  • AIt passes, because the underlayment and the shingles laid over the joint will bridge between the rows of panels and support the unsupported panel edges above.

    The roof covering is not a structural element and bridges nothing. Two unsupported panels deflect independently at the joint, which telegraphs through the shingles and concentrates stress at the fastener line.

  • It fails, because at this support spacing the unsupported panel edges need approved panel clips, tongue-and-groove edges, or blocking beneath the joint.
  • CIt fails, because roof sheathing has to be at least three-quarters of an inch thick wherever the trusses are spaced 24 inches on center below it.

    Sheathing thickness is set by the panel span rating, and this panel is rated for 24-inch spacing provided the edges are supported. Substituting a thickness rule ignores the condition the rating carries.

  • DIt passes, because edge support at unsupported panel joints is a floor sheathing requirement and does not carry over to a roof deck of this kind.

    Edge support applies to both roof and floor sheathing, with the roof condition tied to the wider support spacings. Treating it as a floor-only rule leaves a deck that ridges along every long joint.

Why B is correct

Where the panel rating requires edge support at the support spacing being used, the joint between panel rows has to be handled by approved panel clips, tongue-and-groove edges, or solid blocking. None of those are present, so the deck does not meet the rating on its own stamp. Adding clips at the midpoint between trusses is the normal correction and restores the load sharing the rating assumes.

What this question is testing

Whether the candidate reads a panel span rating as a set of conditions rather than a single number, and knows the three accepted means of supporting an unsupported panel edge. It also tests refusing to let the roof covering stand in for structural continuity.

On the job

Missing clips are easy to spot from the ground once the shingles are on, because the roof plane shows a wavy line at every panel row. That is far too late. At the sheathing inspection, walk the deck and look at the long joints, and check the stamp rather than assuming, since thicker panels at closer spacing may not require clips at all. On reroofs where the old deck stays, the same evaluation applies to what is already there.

Memory technique

Every long joint on a deck needs a clip, a tongue, or a block under it.

Exam tip

When a stem quotes a span rating with the words edge support, the answer is clips, tongue-and-groove, or blocking.

Where to look it up

IRC Chapter 8, roof sheathing, and the wood structural panel tables with the footnotes covering edge support and panel orientation.

4. The joists lap about 1 inch past one another over the wall and are held with a single 8d toenail into the top plate, with nothing fastening the two lapped members to each other. How should the inspector judge this splice?

  • AAccept it; the joists bear on the wall below them, so the connection between the two lapped lengths carries no load at all

    Bearing is only half of what these members do. As rafter ties they carry tension along their length, and a connection that carries no tension breaks the tie in the middle.

  • Reject it; the lapped ends must be joined so the tie is continuous, with the lap and nailing the schedule requires
  • CAccept it; a lapped joist splice is complete once each member is toenailed to the plate it bears on

    Toenailing to the plate holds the member in position vertically. It does nothing to connect the two lengths to each other, which is what the tie requires.

  • DReject it; ceiling joists may not be spliced over a partition and must run in one length from wall to wall

    Splices over a bearing partition are ordinary and permitted. The requirement is that the splice be made properly, not that the members run full length, which would be impractical on most houses.

Why B is correct

Ceiling joists that act as rafter ties are in tension, and the tension has to cross the splice over the bearing wall. The lapped ends must be lapped at least 3 inches and nailed to each other to the schedule, or joined with an approved splice, rather than merely toenailed to the plate.

What this question is testing

Whether the candidate recognizes ceiling joists doubling as rafter ties, understands the splice carries tension, and knows what a compliant lapped splice requires beyond bearing.

On the job

This is one of the most consequential defects an inspector can catch on a stick-framed roof, and it is nearly invisible from the attic hatch unless someone crawls over to the bearing wall. The symptoms appear years later as a sagging ridge, cracks over the exterior wall lines, and doors that stop closing. Adding a properly nailed lap or a splice plate takes minutes while the attic is open.

Memory technique

A tie with a broken middle is not a tie.

Exam tip

Ask what the ceiling joist is doing. If it is the rafter tie, the splice carries tension.

Where to look it up

IRC Chapter 8, roof framing, ceiling joists and rafter ties, with the fastening schedule for lapped members.

5. The roof is framed at 2 units vertical in 12 units horizontal, and both units are mounted flat on the deck with the flashing kit lapped into the roofing and no curb beneath them. How should the inspector judge this installation?

  • AAccept it; the flashing kit supplied with the unit is the manufacturer's tested detail and applies at any roof slope

    A flashing kit is tested for the mounting it is made for. Deck-mount and curb-mount kits are different products, and the slope determines which one applies.

  • BAccept it; curbs are required only where a skylight is site built rather than a listed factory-built unit

    The curb requirement is keyed to roof slope and applies to factory-built unit skylights. Site-built skylights carry their own separate requirements.

  • Reject it; on a roof flatter than 3 units in 12 a unit skylight is mounted on a curb at least 4 inches above the roof plane
  • DReject it; unit skylights are not permitted on any roof flatter than 4 units in 12 and must be relocated to a steeper plane

    Unit skylights are permitted on shallow roofs, on a curb. Prohibiting them outright is stricter than the code and would rule out a common and well-performing installation.

Why C is correct

Unit skylights on roofs with a slope flatter than 3 units vertical in 12 units horizontal must be mounted on a curb that extends not less than 4 inches above the plane of the roof, so the frame and its seals sit above water and snow that stand on a shallow roof.

What this question is testing

Whether the candidate knows the curb requirement for unit skylights is triggered by roof slope, recalls both the slope threshold and the curb height, and recognizes that mounting type governs which flashing applies.

On the job

Low-slope dormers, porch roofs and additions are where this comes up, and the skylight is usually already in when the inspector arrives. The check takes a level, a rule and a look at whether the frame sits proud of the roof surface. The consequence of getting it wrong is a leak at the head of the unit that appears with the first wet snow and is blamed on the skylight rather than on the mounting.

Memory technique

Shallow roof, tall curb.

Exam tip

Flatter than 3 in 12 means a curb, and the curb is at least 4 inches tall.

Where to look it up

IRC Chapter 3, glazing, the skylight section covering unit skylights and curb mounting.

6. Lifting a shingle course you find the shingles nailed directly to the wood structural panel deck, with no underlayment of any kind between them. What is the correct finding?

  • AAccept it; underlayment is required only on slopes below 4 units vertical in 12 units horizontal

    The slope threshold changes the number of underlayment layers, from one on steeper roofs to two on shallow ones. It does not remove the requirement for a steep roof.

  • BAccept it; self-sealing shingles form a continuous membrane once the tabs seal in warm weather

    A sealed shingle field is not a membrane. Water routinely gets behind shingles in wind-driven rain and at every fastener, which is what the underlayment is there to handle.

  • Reject it; underlayment is required beneath the roof covering, so this work has to be lifted and redone
  • DReject it; the deck must be covered with an ice barrier over its entire area before shingles are applied

    Ice barriers are required in specified climates along the eaves and at other vulnerable locations, not over the whole roof. Requiring full coverage confuses a targeted requirement with the general underlayment rule.

Why C is correct

Underlayment is required under the roof covering at all slopes. What changes with slope is the number of layers and how they are applied, not whether underlayment is needed. The shingles already laid must come off and be reinstalled over underlayment.

What this question is testing

Whether the candidate knows underlayment is required at all slopes, understands what changes with slope, and does not confuse the general requirement with the targeted ice barrier provisions.

On the job

This is rare but it happens on small jobs and owner work, and it is caught by lifting a course at the rake. Once caught, the conversation is unpleasant because the correction means removing shingles that are already fastened and, in warm weather, already sealed. Where only a portion is done, catching it early is the difference between one square and the whole roof.

Memory technique

One layer steep, two layers shallow, never none.

Exam tip

Underlayment is always required. Slope decides how many layers, not whether.

Where to look it up

IRC Chapter 9, roof coverings, the underlayment requirements for asphalt shingles.

7. The partition is sheathed solid with no air path through it, leaving one space of 900 square feet and another of 750 square feet. The governing ratio is 1 square foot of net free ventilating area for each 150 square feet, and all 1,584 square inches of installed vents open into the larger space. What is the finding?

  • AIt complies, because 1,584 square inches covers the 1,650 square feet of attic area in the house

    The total is right and the distribution is not. Air does not cross a solid sheathed partition, so vents on one side do nothing for the space on the other.

  • BThe smaller space needs 864 square inches of its own, and none has been provided for it

    That figure is what the 900-square-foot space requires. Applying the larger space's requirement to the smaller one overstates it and shows the two areas were not kept apart.

  • The smaller space needs 720 square inches of its own, since each separated space is ventilated on its own
  • DThe smaller space needs 360 square inches, because a space under 1,000 square feet may use the reduced ratio

    No provision reduces the ratio because a space is small. The reduced ratio depends on where the vents are placed or on a vapor retarder, and neither has anything to do with the size of the attic.

Why C is correct

Each enclosed attic space is ventilated on its own area. The 750-square-foot space requires 750 divided by 150, or 5 square feet, which is 720 square inches of net free area, and nothing has been provided on that side of the partition.

What this question is testing

Whether the candidate recognizes that a separated attic space is figured and ventilated independently, and computes the requirement for the space that was left out.

On the job

Separated attic spaces show up at party walls in duplexes and townhouses, over attached garages, at fire-rated separations, and wherever a bonus room's knee walls close off the space behind them. Each pocket has to breathe. The classic failure is the small attic over a projecting wing or a porch roof that is sealed at the main roof and given no vents of its own, which shows up years later as rusted fasteners and stained sheathing.

Memory technique

Air does not go through a wall to get to a vent.

Exam tip

Count spaces before you count vents. Solid partitions make two attics.

Where to look it up

IRC Chapter 8, roof ventilation, the requirement for enclosed attics and rafter spaces.

55 more in the bank

Answers and explanations for these are in the app.

  • The attic above the second floor covers roughly 900 square feet and has about 6 feet of vertical height at the ridge, and it contains no mechanical equipment. The builder says no access was provided because nothing up there needs servicing. What is the correct finding?
  • The builder wants to use the reduced ventilation ratio of 1 square foot for each 300 square feet of attic area. Which arrangement of openings allows that reduction to be used?
  • At the perimeter the blown insulation has been carried out over the top plate and packed tight against the underside of the roof sheathing, completely filling the space above the soffit inlets, and no baffles were installed. What is the correct finding?
  • The ceiling joists are 2 by 6 members sized on the approved plans for an uninhabitable attic with limited storage loading, and the owner has decked roughly 400 square feet and filled it with boxes, furniture and paint. How should the inspector handle this?
  • The rafters are nailed to a 1 by 8 board at the peak, there are no ceiling joists and no rafter ties anywhere in the assembly, and at each end the board simply stops against the gable framing without any post or support beneath it. What is the correct finding?
  • The framer has also installed 1 by 4 boards connecting opposing rafters at roughly mid-height of the attic space, spaced about 8 feet apart, and calls them the collar ties for the roof. Judging those members against the code, what is the correct finding?
  • The rafters bear on the exterior wall plates, the ceiling joists run perpendicular to them, no separate ties connect opposing rafters near the plate line, and the member at the peak is a nailed 1 by 8 board with no support beneath its ends. What is the correct finding?
  • The truss design drawings show continuous lateral bracing on specified web members with diagonal bracing at intervals, and none of it has been installed. The framer says the roof sheathing already braces the whole truss. What is the correct finding?
  • For the species, grade, spacing and load shown, the plans list a maximum rafter span of 18 feet 0 inches. The roof is framed at 6 units vertical in 12 units horizontal, and along the top edge of a rafter you measure 20 feet from the ridge to the outside face of the wall plate. What is the correct finding?
  • The rear wing is framed at 3 units vertical in 12 units horizontal, asphalt shingles are specified, and a single layer of underlayment has been applied in the usual overlapping courses up the slope. What is the correct finding?
  • The porch roof is framed at 1.5 units vertical in 12 units horizontal, and the same three-tab asphalt shingles used on the main roof have been laid on it over a doubled underlayment. What is the correct finding?
  • The roofer installed a self-adhering polymer-modified bitumen sheet along the eaves, and measuring up the slope you find it stops about 12 inches inside the exterior wall line of the building. What is the correct finding?
  • Lifting a course at the rake you count two existing applications of asphalt shingles on the deck, both sound and dry, and the contractor plans to lay a new layer over the top of them. What is the correct action?
  • At the sidewall the roofer ran the shingles tight to the wall and sealed the junction with a continuous bead of roofing sealant, and at the valley the original metal was reused with the shingles butted over it. What is the correct finding?
  • The fireplace opening measures 5 square feet, and the hearth extension in front of it projects 12 inches from the face of the fireplace and 6 inches beyond each side of the opening. What is the correct finding?
  • The masonry chimney terminates 2 feet above the point where it passes through the roof surface, and the ridge of the same roof stands 8 feet away horizontally with its peak 1 foot below the top of the chimney. What is the correct finding?
  • Laying a tape along the top edge of one member from the wall plate up to the peak, you read 20 feet 0 inches, and the pitch is 9 units vertical in 12 units horizontal. The approved plans give a maximum allowable rafter span of 16 feet 6 inches for the species, grade, spacing and loading used here, with a note that span is taken along the horizontal projection. How should the inspector rule?
  • The rafters bear on the exterior wall plates and are nailed to a ridge board at the peak. The only members connecting opposing rafters are ties installed at a height roughly halfway between the plate line and the ridge, and no engineered design has been submitted for the roof. Where does the code place prescriptively designed rafter ties?
  • The ceiling joists run parallel to the rafters and the plans rely on them as the rafter ties. Each joist runs from the exterior wall and stops over the center bearing wall, where it is toenailed to the plate alongside the joist coming from the other side, with no lap and no splice plate. The framer says the bearing wall carries the joists so nothing more is needed. How should the inspector rule?
  • The common rafters are 2x10 members. The valley rafters where two roof planes meet are 2x8, and the hip rafters are 2x6. Where the common rafters are cut into the valley, the plunge cut on the common rafter is deeper than the face of the 2x8 valley member. No engineered design has been submitted. How should the inspector rule?
  • To get a duct past one truss, the installer cut roughly 4 inches out of a vertical web member and left both chords untouched. The superintendent points out that the chords were not damaged and offers to nail plywood gussets on both faces of the cut web before you leave. How should the inspector rule?
  • Each truss heel bears on the double top plate and every truss is held with two toenails and nothing else. The truss design drawings delivered with the package show an uplift reaction at each bearing point and state the required bearing width. No metal connectors have been installed anywhere along either bearing wall. How should the inspector rule?
  • The roof sheathing is 7/16-inch wood structural panel over rafters at 24 inches on center. Snapping lines over the rafters, you find 8d nails at roughly 6 inches on center along the panel edges but 16 to 18 inches apart in the field, and several rows of field nails have missed the rafter entirely and are visible from the attic. The approved fastening schedule calls for 8d at 6 inches on edges and 12 inches in the field. How should the inspector rule?
  • The vented attic has 1,800 square feet of ceiling area. The condition allowing the reduced ratio has not been met, so the required ventilating area is 1 square foot for each 150 square feet of the area ventilated. The builder installed 16 soffit vents. Each vent has a gross opening of 8 inches by 16 inches, and the manufacturer's listing gives 65 square inches of net free area per vent after the louvers and insect screening are accounted for. How should the inspector rule?
  • The vented attic measures 2,100 square feet. The two ratios available are 1 square foot of net free ventilating area for each 150 square feet of the area ventilated, and a reduced 1 square foot for each 300 square feet where the required condition is met. The builder has placed 55 percent of the ventilating area in ventilators located in the upper portion of the attic, at least 3 feet above the eave vents, with the balance provided by eave vents. Which required area applies?
  • The soffit and ridge vents have been sealed off, closed-cell spray foam is applied in direct contact with the underside of the roof sheathing, and there are no ventilating openings anywhere in the assembly. The insulation contractor has also stapled a continuous polyethylene sheet across the ceiling joists below the attic. How should the inspector rule?
  • The hatch is a rough-framed opening 22 inches by 30 inches cut into the ceiling of a bedroom closet. Standing on a ladder with your head through the opening, you measure 24 inches of vertical clear height from the opening up to the underside of the framing above. The attic exceeds 30 square feet in area and has more than 30 inches of vertical height at its peak. Which finding requires a correction?
  • The main roof is framed at 5 units vertical in 12 units horizontal and the porch roof at 3 units vertical in 12 units horizontal. Wood shakes are being applied to both surfaces. The minimum slopes are 3 units in 12 for wood shingles and 4 units in 12 for wood shakes. How should the inspector rule?
  • Step flashing has been woven correctly into the shingle courses the whole way up the sidewall. At the bottom of that run, where the roof edge meets the wall above the gutter, the step flashing simply stops at the last course and the wall cladding continues past it down to the trim, with nothing turning the water away from the wall. How should the inspector rule?
  • The house carries a single existing layer of asphalt shingles. Lifting shingles in several places you find the wood structural panel deck beneath is water-soaked over large areas around the chimney and along one valley, with the panel faces delaminating. The roofer proposes to lay the new shingles over the existing single layer. How should the inspector rule?
  • The framer has run the floor and ceiling framing tight against the sides of the masonry chimney, with header ends nailed hard to the brick face and the joists in contact with the masonry along their length. The chimney is fully enclosed by framing on all sides, so it is an interior chimney. How should the inspector rule?
  • A wood mantel shelf projects 8 inches out from the face of the fireplace, and its underside sits 10 inches above the top of the fireplace opening. Painted wood trim boards run up each side of the opening 4 inches from its edge and project 3/4 inch from the face. The applicable rules are that combustible material may not be placed within 6 inches of the fireplace opening, and combustible material within 12 inches of the opening may project no more than 1/8 inch for each 1 inch of clearance from the opening. How should the inspector rule?
  • The roofer applied the strip shingles with four fasteners per shingle in the standard pattern. The approved plans and the shingle manufacturer's printed high-wind instructions both call for six fasteners per shingle at the design wind speed shown for this site. How should the inspector rule?
  • The approved plans reproduce two rows from the rafter span table for 2x8 members at 16 inches on center under the loading for this roof: Douglas fir-larch No. 2 permits a span of 13 feet 5 inches, and spruce-pine-fir No. 3 permits 10 feet 2 inches. The rafters actually installed carry a spruce-pine-fir No. 3 grade stamp. The horizontal projection you measure from the plate to the ridge is 12 feet 6 inches. How should the inspector rule?
  • Each new rafter bears 1 1/4 inches on the wood ledger and 2 1/2 inches on the masonry wall, and nothing else supports the rafter ends. The prescriptive bearing requirements are not less than 1 1/2 inches of bearing on wood or metal and not less than 3 inches on masonry or concrete. How should the inspector rule?
  • The rafters are spaced 24 inches on center and the opening interrupts three of them, so the header runs between the trimmer rafters on either side of those three. The framer cut the three rafters and framed the opening with a single header at the head and a single header at the sill, each end nailed with three 16d nails into a single trimmer rafter. Single members are permitted where the header span does not exceed 4 feet, doubling is required beyond that, and approved hangers are required where the header span exceeds 6 feet. How should the inspector rule?
  • The plumbing vent stack comes through the roof and the roofer has fitted a boot with a collar over the pipe. The boot flange is laid on top of the shingle course below it and on top of the shingle courses above it as well, with a heavy bead of roof cement around the whole perimeter, and no shingles lap over the upper part of the flange. How should the inspector rule?
  • The porch is framed at 2 units vertical in 12 units horizontal, and the panels are through-fastened with lapped, nonsoldered side seams and no lap sealant. How should the inspector judge this installation?
  • The chimney measures 48 inches across the slope, and the roofer has run step flashing and counterflashing around all four sides with the upslope side detailed exactly like the sides. What does the code require here?
  • The rafters on one side of the ridge are offset roughly 4 inches from the rafters on the other side along much of the length of the ridge, and the ridge board is a nominal 1x8. What does the code require of this framing?
  • The hearth extension is 3/4-inch stone tile bedded in thinset directly on the wood subfloor, the firebox floor is level with the room floor, and the extension projects the required distance from the opening. What is the correct finding?
  • The valley metal and the step flashing at the two sidewalls are rusted through in several places, and the roofer intends to reinstall them under the new shingles to save the cost of new metal. How should the inspector respond?
  • The vented attic has 1,950 square feet of ceiling area, the applicable ratio is 1 square foot of net free ventilating area for each 150 square feet, and the installed vents total 1,500 square inches of net free area. Where does this attic stand?
  • The vented attic measures 3,000 square feet. Using the reduced ratio of 1 square foot for each 300 square feet, the code requires between 40 and 50 percent of the required ventilating area to be in the upper portion of the space. What is the least net free area that must be placed in the upper portion?
  • The vertical distance from the top plate line to the ridge measures 12 feet 0 inches, and collar ties are required in the upper third of the attic space. Measured above the top plate, what is the lowest point at which a collar tie may be installed?
  • The schedule gives an allowable clear span of 11 feet 6 inches for the beam used. The ridge runs 24 feet 0 inches between the bearing points at the gable walls, with one 3 1/2-inch-wide post supporting the beam at midspan. What is the clear span of each segment?
  • The rafters are 2x8 members with an allowable span of 12 feet 4 inches for this loading. The horizontal projection from the wall plate to the ridge measures 20 feet 0 inches, and the purlin supports the rafters at a point 9 feet 0 inches horizontally from the plate. How do the rafters stand?
  • The deck under the shakes is 1x6 boards laid with 4-inch gaps between them, and the roofer plans to install asphalt shingles directly over those spaced boards. What is the correct finding?
  • The back and side walls of the firebox are 8 inches of solid brick with no firebrick lining, and the mason says 8 inches has always been enough. What does the code require of these walls?
  • Looking up along the ridge from inside, you find the sheathing runs unbroken to the peak on both sides, with the ridge vent and cap shingles installed over solid deck along the entire length. What is the correct finding?
  • The deck is visibly damp in patches, the air temperature is 38 degrees, and the manufacturer's instructions in the bundle wrapper call for a dry deck and hand sealing of every tab below 40 degrees. How should the inspector respond?
  • The clay flue liner sections are stacked with wide mortar joints, several of which have squeezed into the flue and been left with mortar hanging inside, and one joint is open on the back side. What is the correct finding?
  • The vented attic measures 2,760 square feet. The installed vents total 1,325 square inches of net free area, which the builder sized on the reduced ratio of 1 square foot for each 300 square feet. You find that neither condition allowing the reduced ratio has been met, so the ratio of 1 square foot for each 150 square feet governs. What additional net free area is required?
  • The vented attic measures 1,680 square feet and the governing ratio is 1 square foot of net free ventilating area for each 150 square feet. The ridge vent is rated at 12 square inches of net free area per lineal foot and runs 56 feet. The continuous soffit vent is rated at 9 square inches of net free area per lineal foot. How many lineal feet of soffit vent are needed to make up the balance?
  • The vented attic measures 1,500 square feet and the governing ratio is 1 square foot of net free ventilating area for each 150 square feet. Each vent the builder is using has a gross opening of 128 square inches, and the cut sheet lists its net free area as 60 square inches. How many of these vents does the attic require?

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