Roof options for the 40' × 29'-11" panel house

All three use the roof-panel system from the roof project (cellular concrete cast on cold-formed studs, picked and set on the wall tops), sized to this house: bearing on the front and back walls plus the bedroom wall 15.5' in from the front. The roof project's spec found a 6" stud cannot clear-span past about 10.5', so every option names the stud it needs. Costs are order-of-magnitude, scaled from the roof estimate's $38/sf (roof-panel-estimate v7 (6 Sep 2026): $19,818 / 525 sf, which already includes labor, Eco Finish and 10 % contingency) plus the items each option adds; the crane is priced at $1,500 a day. Options 1 and 3 are both built into the 3D model and the estimate — pick either with the “roof design” switch in the control panel.

Option 1

Low-slope flat roof

as designed in the roof project

bedroom wall (bearing)frontback13.5" panel10' walls
P1P2P3▼ view side · 42' × 31'-11" roof plan · 3 panels 14' wide
Roof area1,341 sfPanels3 × 14' wide
Spans (wall to wall)15.5' + 13.5'Studs800S162-68 @ 16" (8" studs) or 600S162-68 @ 12" — PE to pick; the 15.5' front span is past the 6" stud's 10.5' limit
Panel13.5" thick · 44 psf deadSlope1/16"/ft toward the back, drains behind the house
Cellular concrete51.7 yd³ neatHeaviest pick10,259 lb
Roof panels at $38/sf × 1,341 sf$51,300
Crane, 1 day$1,500
Order of magnitude$52,800 · $39/sf
  • Cheapest: least roof area, one pick day, the roof project as built
  • Flat 9' ceiling everywhere; the cast underside is the finished ceiling
  • Simplest wall tops: one continuous top track, no gable or clerestory panels
  • Needs 8" studs (or 6" at 12") because the open zone is 15' deep
  • Low slope: relies on the membrane; ponding risk if the slope is lost
  • No attic; all roof drains run to the back wall
Option 2

Gable roof, 4:12

ridge over the bedroom wall, vaulted open zone

bedroom wall (bearing)frontbackridge beamridge 15'-4"15.5" panel10' walls
F1B1F2B2F3B3ridge▼ view side · 42' × 33'-11" roof plan · 6 panels 14' wide
Roof area1,502 sfPanels6 × 14' wide
Spans (wall to wall)18.0' + 16.0'Studs1000S200-97 @ 16" (10" studs, roof spec Option B) — clear-spans each slope; 6" studs would need a mid-slope purlin
Panel15.5" thick · 50 psf deadSlope4:12 both ways; ridge 15'-4" above the floor, eaves at the wall tops
Cellular concrete53.3 yd³ neatHeaviest pick6,084 lb
Roof panels at $40/sf × 1,502 sf$59,700
Ridge beam + posts hidden in the bedroom wall (allowance)$3,500
Crane, 2 days (6 picks)$3,000
Gable-end infill: 2 triangular wall panels (allowance)$3,200
Order of magnitude$69,300 · $46/sf
  • Vaulted ceiling over the whole open zone, 9' at the walls rising to ~15' at the ridge
  • Sheds rain both ways with real eaves; membrane is a safety, not the whole system
  • Six lighter picks (~6,000 lb) instead of three 10,000 lb picks
  • Most roof area and concrete; 10" studs add ~12 psf and cost
  • Ridge beam plus two gable-end wall triangles are extra items
  • Top pour on a 4:12 slope needs a stiffer cellular mix and screeding uphill
Option 3

Shed roof to the view, 1:12

front wall raised, clerestory glass over the big windows

bedroom wall (bearing)frontbackclerestory12'-6"13.5" panel10' walls
P1P2P3▼ view side · 42' × 32'-11" roof plan · 3 panels 14' wide
Roof area1,387 sfPanels3 × 14' wide
Spans (wall to wall)15.5' + 13.5'Studs800S162-68 @ 16" (8" studs) — same spans as Option 1
Panel13.5" thick · 44 psf deadSlope1"/ft rising to the front; front wall 12'-6", back wall 10'; drains to the back
Cellular concrete49.2 yd³ neatHeaviest pick10,617 lb
Roof panels at $38/sf × 1,387 sf$53,100
Taller front wall panels (10 panels at +2'-6", allowance)$2,600
Clerestory glazing band 100 sf @ $60/sf (allowance)$6,000
Crane, 1 day$1,500
Order of magnitude$63,200 · $46/sf
  • Ceiling rises toward the view: 9' at the back, ~11'-6" at the front glass
  • A clerestory band above the seven windows: more light and view without bigger panels
  • One plane, three picks, drains away from the view side like Option 1
  • Front wall panels are taller than the 10' standard (or a separate clerestory frame)
  • Same 8" stud requirement as Option 1
  • Side walls B and D get a sloped top track

Side by side

Option 1 · Low-slope flat roofOption 2 · Gable roof, 4:12Option 3 · Shed roof to the view, 1:12
Roof area1,341 sf1,502 sf1,387 sf
Panels / picks3 · max 10,259 lb6 · max 6,084 lb3 · max 10,617 lb
Cellular concrete51.7 yd³53.3 yd³49.2 yd³
Studs800S162-68 @ 16"1000S200-97 @ 16"800S162-68 @ 16"
Ceiling9' flat9' to 15'-4" vaulted9' back to 12'-6" front
Extras beyond the panels$1,500$9,700$10,100
Order of magnitude$52,800$69,300$63,200

Basis: footprint 40' × 29'-11" from wall.config.json; bedroom bearing wall at 15' inside from the front (floor-plan.json). Cellular concrete at 35 pcf, 4 psf steel; picks at the 6.5" ground pour. Rates from the roof estimate; ridge beam, gable infill, taller front panels and clerestory glazing are allowances to be replaced with quotes. Edit scripts/roof-options.mjs to change any of these.