Residential Permit Drawings: What a Plan Reviewer Checks

Why this matters

A residential permit set that comes back with comments costs a review cycle, and in a busy building department that is one to three weeks with the crew booked and the customer asking why nothing is happening. Most of those comments are not about bad design. They are about information the reviewer needed and could not find: no code edition, no setback dimension, an egress window with no size, smoke alarms shown only in the new room. A shop that draws its own small additions and remodels can get most sets through on the first pass by drawing to the reviewer's checklist instead of to its own memory of what the job needs.

The process side, from application to final inspection, is its own card. See related: Residential Permit Process + Code Compliance. This one is about what the drawings have to show.

Who the reviewer is and what binds them

The plan reviewer works for the building department, the authority having jurisdiction (AHJ). They review against the model code their jurisdiction has adopted, usually some edition of the International Residential Code (IRC) with local amendments, plus the local zoning code for where the building may sit. Neither the IRC nor any model code is law until a state or local government adopts it, and adoption edition varies widely: one county may enforce the 2021 IRC while the next is on 2015. Everything below is stated against the 2021 IRC as a model; check your jurisdiction's adopted edition and amendments, which the department usually posts.

Who may prepare residential drawings is set by state law and local rule, not by the code. Many places let a homeowner or a contractor draw a simple addition, while structural work outside the code's prescriptive tables commonly needs a design professional's seal. Check your own state before you put your name in the title block.

The checklist the reviewer is working from

Departments publish their own versions, and they differ in detail. The shape below is close to what most use for a small addition or remodel. The bracketed marks are the review of the worked example further down.

PLAN REVIEW  RES ADDITION / ALTERATION   REVIEW 1
---------------------------------------------------
[X] 1 CODE EDITION + LOCAL AMENDMENTS NOTED
[X] 2 SITE PLAN: LOT LINES, SETBACKS TO NEW WORK,
      EASEMENTS, EXISTING BUILDINGS, NORTH, SCALE
[ ] 3 FLOOR PLAN: ROOM USES, DIMS, EXIST VS NEW
[X] 4 EGRESS: EACH SLEEPING ROOM, NET CLEAR
      OPENING, HEIGHT, WIDTH, SILL HEIGHT
[X] 5 SMOKE + CO ALARMS: NEW AND EXISTING AREAS
[X] 6 STRUCTURE: FOOTING, FRAMING, HEADERS, BEAMS
[X] 7 ENERGY: COMPLIANCE PATH, R-VALUES, U-FACTOR
[ ] 8 STAIRS + GUARDS (IF ANY)
[X] 9 MEP: CIRCUITS, FIXTURES, EQUIPMENT SIZING
[ ] 10 SHEET INDEX, PREPARER, SHEETS AGREE
---------------------------------------------------
[X] = COMMENT ISSUED          7 OF 10 ITEMS

What each line is really asking

1. Code edition. One line on the cover sheet: "Designed to the 2021 IRC as adopted by [jurisdiction], with local amendments." Without it the reviewer cannot tell whether a dimension that fails the current edition was drawn to an old one by mistake.

2. Site plan. Lot lines with dimensions, the existing house, the new work, and the distance from the new work to every lot line it approaches. Setbacks are zoning, a local ordinance, so the IRC is silent on them, and they are the most common site comment because the site plan shows the lot lines but never dimensions to the new wall. The reviewer also checks fire separation distance under IRC R302.1: in substance, an exterior wall closer than 5 ft to the lot line needs a fire-resistance rating, with the details in Table R302.1 of the adopted edition.

3. Floor plan. Every room labeled with its use, because the use drives the rules: a room labeled "office" with a closet is often read as a sleeping room, and then it needs an egress opening and a smoke alarm. Existing and new walls drawn differently, with a legend.

4. Egress. Under IRC R310 in the 2021 edition, every sleeping room, and basements with habitable space, needs an emergency escape and rescue opening. For a window that means a net clear opening of at least 5.7 sq ft (5.0 sq ft for a grade-floor or below-grade opening as the code defines them), at least 24 in clear high and 20 in clear wide, with the sill no more than 44 in above the floor. Net clear is the opening with the sash open, from the window maker's published data, not the rough opening or the unit size.

5. Alarms. Smoke alarms under IRC R314 go in each sleeping room, outside each separate sleeping area in the immediate vicinity of the bedrooms, and on each story. Carbon monoxide alarms under IRC R315 apply where the house has a fuel-fired appliance or an attached garage, outside each separate sleeping area. For alterations and additions that need a permit, R314 and R315 in substance require the existing house to be brought up to those locations, with exceptions the code lists, including some exterior-only work and some plumbing or mechanical work; check the exceptions in the adopted edition. This is why a plan that shows a new alarm only in the new bedroom almost always comes back.

6. Structure. Footing size and depth, floor and roof framing with member size, spacing and span, and every header and beam sized, with its bearing. The IRC's prescriptive tables cover common cases; anything outside them, or any engineered beam, needs the supplier's or an engineer's sizing attached. A new opening cut in an existing bearing wall with no header shown is a near-certain comment.

7. Energy. The compliance path (prescriptive or a software performance report) and the numbers it uses: insulation R-values by assembly and window U-factors, under IRC Chapter 11 or the residential IECC as adopted. The values depend on climate zone, so this line cannot be filled from a sibling job in another county.

8. Stairs and guards. If there is a stair, riser height, tread depth, headroom and handrail are drawn and dimensioned against IRC R311.7, and any walking surface more than 30 in above the floor or grade below gets a guard under IRC R312.1. Decks and landings at an addition's door trip this more often than interior stairs do.

9. MEP. New circuits, outlets and protection notes on the electrical layout; new fixtures and their drains on the plumbing; and for new heating or cooling equipment, IRC M1401.3 in substance requires it be sized from a load calculation, so many departments ask for the calculation itself.

10. Consistency. A sheet index, the preparer's name, and sheets that agree. A floor plan and a framing plan that show the addition at different depths gets the whole set returned.

Worked example: a rear bedroom addition, review 1

A shop draws a 14 ft wide by 16 ft deep bedroom addition on the back of a one-story house with a gas furnace and two existing bedrooms. It submits a site plan, a floor plan, a framing plan and an elevation. The review comes back with seven comments, one for each item marked above.

1. No code edition. Fix: one note on the cover sheet. Five minutes.
2. Rear setback. The site plan dimensions the existing rear wall at 38 ft from the rear lot line and does not dimension the addition. The reviewer subtracts: 38 minus 16 leaves 22 ft. The local zoning code (in this example) requires 25 ft, so the addition is 3 ft into the setback. Fix: shorten the addition to 38 minus 25, or 13 ft deep, which makes the room 13 by 14, or 182 sq ft against the 224 sq ft first drawn, or apply for a variance, which is a separate process and a separate wait. The owner takes 13 ft. The floor plan, framing plan and roof framing all change, which is why item 10 matters on the resubmittal.
3. Egress. The plan calls for a 3 ft by 4 ft double-hung window. The maker's data gives its net clear opening with the lower sash up as about 32 in wide by 20 in high: 32 times 20 is 640 sq in, divided by 144 is 4.44 sq ft. That fails the 5.7 sq ft minimum, and the 5.0 sq ft a grade-floor opening is allowed as well, and the 20 in height fails the 24 in minimum on its own. Fix: a casement whose published net clear opening is 22 in wide by 44 in high: 22 times 44 is 968 sq in, or 6.72 sq ft, which passes, and 44 in high and 22 in wide pass their minimums. The plan now gives the sill height, 24 in above the floor, which is under the 44 in maximum.
4. Alarms. Only the new bedroom showed a smoke alarm. Because the house has a gas furnace and this is a permitted addition, the reviewer requires smoke alarms in both existing bedrooms and in the hall outside them, and a CO alarm in that hall. Fix: show all four new alarm locations, and note interconnection, which the code in substance requires where it can be done without removing finishes. The drawing change is small; the electrical scope is not, so the estimate changes too.
5. Header. The addition opens to the house through a new 6 ft opening in the existing rear wall, which carries the roof. The framing plan showed the opening and no header. Fix: a header sized from the adopted code's header table for the span, roof load and building width, with jack studs, or an engineered beam with the supplier's sizing sheet attached.
6. Energy. Nothing given. Fix: a prescriptive table for the climate zone listing wall, ceiling and floor R-values and the window U-factor, with the new casement's rating from its label data.
7. Equipment. The plan noted "extend existing ductwork to new bedroom." The reviewer asks whether the existing furnace and air conditioner can serve 182 more square feet. Fix: a room-by-room load calculation for the house with the addition, showing the existing equipment is adequate, or a sizing for new equipment.

Counting the cost. Four comments (1, 3, 5, 6) are fixes to the drawings that take an hour or two in total. Two (2 and 4) change the scope and the price. One (7) needs a calculation the shop may have to buy or learn to do. All seven are information the reviewer needed and could not find, which means all seven could have been on the first submittal.

What would have changed the review. If the house had no fuel-fired appliance and no attached garage, the CO half of comment 4 would not apply, though the smoke alarm half still would. If the zoning code allowed a 20 ft rear setback, comment 2 would have been only a missing dimension, and the room would have kept its 16 ft depth.

The comments that send sets back most often

From the reviewer's side of the counter, the repeat offenders are: no setback dimensions to the new work; a room that can be read as a bedroom without an egress opening; alarms shown in new space only; a new opening in a bearing wall with no header; energy information missing or copied from another climate zone; and a plan, framing plan and elevation that disagree with each other after a late change. A shop that checks those six before it submits avoids most second rounds.

How to verify a set before it goes in

• Every line of your department's checklist can be pointed to on a specific sheet, and you can name the sheet.
• Every distance the zoning code cares about is a written dimension, not something the reviewer has to scale.
• Every sleeping room has a window with its net clear width, height, area and sill height written on the plan, from the window maker's data.
• Alarm locations cover the existing house as well as the new work, or the plan states the exception that applies.
• The depth of the addition is the same number on every sheet.

This is about what reviewers check, not legal advice on who may prepare or seal drawings in your state.

References

• See related: Residential Permit Process + Code Compliance
• See related: How to Sketch a Floor Plan for a Permit Application; How to Draw a Site Plan for an Outdoor Equipment Permit
• International Residential Code, 2021 edition, Sections R302.1, R310, R311.7, R312.1, R314, R315, M1401.3 and Chapter 11, as adopted and amended by your jurisdiction
• Your building department's published residential submittal checklist, and the local zoning ordinance for setbacks