Examples — Plan & Detail Studies¶

Concrete exercises that mirror real design problems. None of these are full plans — they're the kind of thinking required at each step.

1. Programming a 1,800 sf single-family home¶

Occupants: couple + 2 kids + dog. WFH 1–2 days/week.
Climate zone: 4A (mixed, humid).
Lot: 0.25 acre, west-facing front, mature oaks east side.

Spaces (rough sf, with notes):
  Kitchen / dining / living open plan       450 sf  (cooking-heavy; 9' ceilings)
  Primary suite (bed, bath, closet)         350 sf  (king + reading chair; double vanity)
  2 secondary bedrooms                      250 sf  (jack-and-jill bath shared)
  Office / WFH                              120 sf  (door for calls; not a bedroom by code)
  Mudroom / laundry                         80 sf   (bench, hooks, side-by-side W/D)
  Powder bath                               25 sf
  Mechanical / closet                       35 sf   (heat pump indoor, water heater, ERV)
  Circulation, walls                        ~100 sf
                                            ─────
  Total conditioned                         ~1,410 sf
  Garage (unconditioned, attached, 2-car)   400 sf

Performance targets:
  HERS index ≤ 50 (state requires ≤ 60)
  ACH50 ≤ 1.5
  All-electric (no gas service)
  Solar-ready, EV-ready, battery-optional rough-in

Budget envelope:
  Hard costs: 1,410 sf × $300/sf = $423k + garage $50k = ~$475k
  Soft costs (15%): $71k
  Site, foundation premium, contingency: $90k
  TOTAL ENVELOPE: ~$636k

This is the document you sign yourself before you draw a thing. It defines success.

2. Code-summary cover sheet (fragment)¶

PROJECT INFORMATION
  Address:                  123 Example Ln
  APN:                      012-345-67-890
  Zoning:                   R-1 (Single Family Residential)
  Lot area:                 10,890 sf
  Floor area (proposed):    1,810 sf conditioned + 400 sf garage
  Lot coverage:             19% (max 35%)
  Setbacks:                 Front 25' / Sides 5' / Rear 20' (all met)
  Building height:          22'-6" to ridge (max 30')
  Construction type:        V-B (per IBC) — wood frame, unprotected

APPLICABLE CODES
  2021 IRC w/ State Amendments
  2021 IECC w/ State Amendments
  2020 NEC (NFPA 70)
  2021 IPC, IMC (per IRC adoption)
  2021 IFC

DESIGN LOADS (per IRC R301)
  Ground snow:              25 psf
  Wind:                     115 mph (Vult), Exp B
  Seismic:                  Ss = 0.50, S1 = 0.20  → SDC C
  Soil bearing (assumed):   1,500 psf (verify w/ geotech)

ENERGY COMPLIANCE
  REScheck attached. U-factor and SHGC per IECC Table R402.1.2.
  Climate zone 4A. Performance path used.

This sheet alone is ~30% of plan check. Get it right.

3. Wall section — typical 2x6 wall with continuous exterior insulation (CZ 4A)¶

EXTERIOR (outside to inside):
  - Fiber cement lap siding, 7" reveal
  - 1x4 vertical rain-screen battens (creates drainage gap)
  - Self-adhered WRB (water-resistive barrier) — critical air/water layer
  - 1.5" rigid mineral wool continuous insulation (R-6)
  - 1/2" exterior sheathing (OSB or plywood)
  - 2x6 stud wall @ 16" o.c., R-21 mineral wool batts
  - Smart vapor retarder (variable permeance, e.g., MemBrain)
  - 1/2" gypsum board, painted

CALCULATED PERFORMANCE:
  Whole-wall R-value (parallel paths):  ~R-26
  Vapor profile:                          dries to interior in winter; exterior CI keeps stud cavity warm above dew point
  Air barrier:                            primary at WRB; secondary at gypsum/Membrain
  ACH contribution:                       <0.5 ACH50 if detailed properly

Detail every penetration: windows, doors, hose bibs, electrical entries. Air leakage isn't fields; it's edges.

4. HVAC sizing — Manual J / S / D summary¶

House: 1,810 sf, climate zone 4A, oriented south-facing main glazing.
ENVELOPE: as wall section above; R-49 attic; U-0.25 windows; ACH50 = 1.5.

MANUAL J (block load):
  Heating design load:    18,200 BTU/hr  (10°F outdoor design)
  Cooling design load:    14,800 BTU/hr  (sensible) + 2,800 (latent) = 17,600 total
  Latent heat ratio:      ~0.16 (low; envelope is dry-leaning)

MANUAL S (equipment selection):
  Selected: 2-ton (24 kBTU/hr nominal) variable-speed heat pump (Mitsubishi MXZ inverter or equivalent).
    - Heating capacity at 10°F: 22,000 BTU/hr (sized to avoid resistance backup at design)
    - Cooling capacity at 95°F: 23,500 BTU/hr (target oversize ≤ 25% on cooling)
  Backup: 5-kW resistance strip (rare use; below 0°F only)

MANUAL D (duct design):
  Total external static pressure:   0.5 in.w.c.
  Friction rate:                    0.08 in.w.c per 100 ft
  Trunk: 14" round → 12" → 10" reductions
  Branch ducts: 6"-7" round to each register
  Velocity:                         < 700 fpm in trunks, < 600 fpm in branches (for low noise)
  Total estimated duct leakage:     < 4 cfm/100 sf @ 25 Pa (code threshold; aim better)

Compare to the contractor rule of thumb that would have you buying a 4-ton system. That oversized unit short-cycles, costs more, has worse humidity control, and uses more energy. The Manual J/S/D process exists to prevent that.

5. Electrical load calc (NEC Article 220)¶

For the sample home, all-electric, with EV:

Standard service-load calc (NEC 220.83 Method 1):

  Lighting / general (3 VA × sf):       1,810 × 3 =  5,430 VA
  Small appliance (2 × 1,500 VA):                    3,000 VA
  Laundry:                                           1,500 VA
  HVAC (heat pump 24 kBTU @ ~6 kW):                  6,000 VA
  Electric water heater (heat pump):                 1,500 VA
  Range (electric induction):                        8,000 VA
  Dishwasher / disposal:                             1,500 VA
  Dryer (heat pump):                                 1,200 VA
  EV charger (Level 2, 11.5 kW continuous):         11,500 VA × 1.0 (continuous) = 11,500 VA
                                                  ────────
  Subtotal:                                         39,630 VA

Apply demand factors (NEC 220.83):
  First 10 kVA at 100%, remainder at 40%:
    10,000 + (29,630 × 0.40) = 10,000 + 11,852 = 21,852 VA

  Service amps (240V):                21,852 / 240 = 91 A

Conclusion: 200A service is adequate; consider future-proofing to 200A panel with provisions for additional EV / battery.

The point is: do the math. "200A is standard, just put one in" works most of the time and bites you the day you add a heat pump pool heater.

6. Permit submittal sheet count (typical residential)¶

Cover sheet, code summary, sheet index             A0.0
Site plan                                          A1.0
Survey reference                                   A1.1
Foundation plan                                    A2.0
Floor plan(s)                                      A2.1, A2.2
Roof plan                                          A2.3
Reflected ceiling / lighting plan                  A2.4
Exterior elevations (4 views)                      A3.0
Building sections (2-3 cuts)                       A4.0, A4.1
Wall sections / details (typical, atypical)       A5.0, A5.1, A5.2
Window schedule / details                          A6.0
Door schedule / details                            A6.1
Finish schedule                                    A7.0
Specifications notes                               A8.0
Structural cover, gen notes, design criteria       S0.0
Foundation plan (structural)                       S1.0
Floor framing                                      S2.0, S2.1
Roof framing                                       S3.0
Shearwall / lateral plans                          S4.0
Beam / column / hardware schedules                 S5.0
Details                                            S6.x
Electrical: load calc, panel schedule, plan        E1.0–E2.0
Plumbing: DWV, supply, riser                       P1.0–P2.0
Mechanical: Manual J/S/D, plan                     M1.0–M2.0
Energy compliance (REScheck)                       T1.0
                                                  ─────
Approx. sheet count:                              30–45 sheets

Smaller jurisdictions accept simpler sets; bigger projects push toward 80+.

7. Owner-builder bid analysis spreadsheet (excerpt)¶

Trade	Bidder A	Bidder B	Bidder C	Notes
Excavation	$14,200	$11,800	$13,500	B excludes rock removal; A includes
Foundation	$48,500	$41,000	$52,000	C uses ICF; A/B are stem wall/slab
Framing labor	$62,000	$55,000	$58,000	Material owner-supplied
Roofing	$14,500	$13,200	$15,800	Same shingle spec
Plumbing	$32,000	$28,500	$36,000	C has 25-yr warranty
Electrical	$28,000	$25,000	$30,500	All include 200A panel + 2 EV rough
HVAC	$24,000	$19,800	$27,000	A and C variable-speed; B single-stg
Insulation	$9,500	$8,200	$11,000	C uses dense-pack cellulose
Drywall	$18,500	$16,800	$17,500	Spray-textured
Subtotal	$251,200	$219,300	$261,300

Cheapest bid (B) is not always the right pick. Check: - License/insurance current? - References for similar-size projects in your area? - What's excluded? - Schedule fit? - Quality reputation among other tradesmen?

You usually pick neither the cheapest nor the priciest. Often the middle bid with the best references and clearest scope wins.

8. Construction schedule (Gantt fragment)¶

Week  Activity                                          Critical?
1-3   Site clear, erosion control, utility connect      Yes
4-6   Excavation, foundation, slab cure                 Yes
7-10  Framing (floor, walls, roof)                      Yes
9-11  Roofing (overlaps frame finish)                    Yes
11-14 Windows, exterior wrap, siding rough              Partial
13-16 Plumbing rough, electrical rough, HVAC rough     Yes
16-17 Insulation (after rough inspections)              Yes
17-19 Drywall (board, mud, sand, prime)                 Yes
19-22 Trim, doors, cabinets                             Partial
22-25 Floor finish, paint, fixtures, appliances         Partial
25-26 Final mechanical, electrical, plumbing trim      Yes
26-28 Final inspections, CO                              Yes

Critical path = framing → MEP rough → drywall → final. Anything on critical path that slips slips the whole project. Long-lead items (windows, custom cabinets, panel/breakers, HVAC equipment) must be ordered weeks ahead of need.