Shed Roof Assessment

Baan Suriya Chan (Soluna) · Hin Kong, Ko Pha Ngan · 9.74°N

Solar panels + heat reduction Simpler construction Modern Japandi Passive thermal ventilation
Proposal: Replace the hip roof (30°, four-sided slopes) with a mono-pitch shed roof.
Orientation: High wall on East (pool side, 73° azimuth), slope descending toward West.
Overhangs: East (pool) 4.0m · West 1.5m.
Motivations: Solar panel optimization + roof heat reduction, simpler construction, passive thermal ventilation via Breezway Powerlouvres, clean modern aesthetic.
1 — Pitch Calculator — Dimensions at Different Angles

Shed spans 9.45m E–W. Low wall (West) 3.26m — raised so W eave = 3.0m with continuous slope. East overhang 4.0m, West overhang 1.5m.

PitchW WallE WallHeight Δ E Eave (4m ov)W Eave (1.5m ov)RoofingNotes
5°3.13m3.96m0.83m 4.31m ✓3.0m metal onlyVery subtle slope
7°3.18m4.34m1.16m 4.83m ✓3.0m metal onlyNoticeable, gentle
★ 10° 3.26m4.93m1.67m 5.64m ✓3.0m metal onlySweet spot — dramatic without extreme
12°3.32m5.33m2.01m 6.18m ✓3.0m metal onlyVery tall east wall
15°3.40m5.93m2.53m 7.00m3.0m some tiles OKTall east wall
20°3.55m6.99m3.44m 8.44m3.0m most tiles OKExtreme east height

W wallH = 3.0 + 1.5 × tan(θ) (raised so W eave = 3.0m)  |  E wallH = W wallH + 9.45 × tan(θ)  |  E eave = E wallH + 4.0 × tan(θ)  |  W eave = W wallH − 1.5 × tan(θ) = 3.0m  |  Metal roofing ≥ 3°, concrete/clay tiles ≥ 15°

2 — Cross-Section Comparison (E–W cut, 9.45m span)
Hip Roof

Current Design — 30° hip

Four-sided slopes, ridge at center · from Yuki engineering S1-05

3.0m 5.73m ridge 2.42m eave 2.42m 1.0m 9.45m W E pool →
Proposed

Shed Roof — 10°

Single slope · E overhang 4.0m · W overhang 1.5m

solar panels (shade roof −38% heat) Powerlouvres (hot air exhaust) stack effect airflow air in 4.93m 3.26m 3.0m eave 5.64m eave 1.5m 4.0m overhang +1.67m 10° single slope 9.45m W (low) E (high) pool →
3 — Elevation Comparison

East Elevation (Pool Side, 25m)

The facade seen from the pool — the most important visual

Hip Roof

Hip — East Elevation

Hipped ends slope down at N/S · no vertical gable walls

ridge 5.73m 2.42m eave S N
Proposed

Shed — East Elevation

Clean single roofline at 5.38m · clerestory + Powerlouvres

Breezway Powerlouvres — thermal exhaust + morning light 5.38m eave 4.67m wall single clean roofline — no ridge visible S N

North Elevation (Short End, 9.45m)

Hip Roof

Hip — North End

Hip slope from all sides — no vertical gable wall

ridge 5.73m 2.42m W E
Proposed

Shed — North End

Sloped top: low left (W), high right (E) with Powerlouvres

Powerlouvres 3.26m 4.93m 3.0m 5.64m 10° W (low) E (high)
4 — Interior Ceiling + Thermal Ventilation
Hip Roof

Hip Interior — Symmetric Peak

Raked ceiling with wood lining, ridge beam at center

3.0m 5.73m W E (pool)
Proposed

Shed Interior — Thermal Stack Effect

Cool air enters W (low) → hot air exits E (high Powerlouvres)

air in (W entry door) Powerlouvres hot air exhaust hot air rises along slope → exits high 3.26m 4.93m +1.67m stack W (entry) E (pool)
Passive cooling via Breezway Powerlouvres: The 1.67m height difference between W entry (3.26m) and E Powerlouvres (4.93m) creates a natural stack effect. Hot air rises along the sloped ceiling and exits through the automated louvres on the high east wall. Fresh air is drawn in through openings flanking the west entry door. The Powerlouvre system provides 90% ventilation when fully open, with built-in temperature sensors for automatic operation. (Breezway, Architropics)
5 — Solar Analysis + Roof Heat Reduction
Solar panels as roof insulation: A UC San Diego study (Solar Energy journal, peer-reviewed) found that solar PV panels reduce heat reaching the roof by 38% and keep ceilings 5°F (2.8°C) cooler. The panels act as roof shading — the sun beats on the panels instead of the roof surface, and wind flowing between the tilted panels and roof removes trapped heat. Tilted panels (like on a shed roof) provide more cooling than flat-mounted. (UC San Diego, Conserve Energy Future)
FacadeAzimuth Hip: eave / sun hrs Shed 10°: eave / sun hrs Change
East (pool)73° 2.42m5.2h 5.64m 1.5h −71% sun
West253° 2.42m5.0h 3.0m5.0h ~same
North343° ~3.0m1.5h ~3.8m1.2h −20%
South163° ~3.0m1.8h ~3.8m1.6h −11%

Sun hours = average direct sun on wall at equinox. Hip: ~1.0m overhangs, 30° pitch. Shed: E=4.0m, W=1.5m overhangs (flat soffit), 10° pitch. The dramatically higher E eave (5.64m vs 2.42m) nearly eliminates direct sun on the pool-facing wall.

Sun Path & Shadow Projection — Equinox (Mar/Sep)

Top-down view · house rotated −17° from true N · latitude 9.74°N

N S E W −17° rot 6am sunrise E noon 80° altitude 6pm sunset W solar panels E (pool) — 73° W (entry) — 253° S — 163° N — 343° pool 9am shadow (4m E overhang shades pool) noon — nearly overhead (80° alt, minimal shadow) 3pm shadow (5.64m E eave blocks low W sun) Solar Summary at 9.74°N (near-equatorial) • Equinox noon: sun at 80° altitude — almost directly overhead, tiny shadows • Morning (E sun): 4.0m E overhang + 5.64m eave height = pool fully shaded until ~10am • Afternoon (W sun): low angle sun hits W side, but entry/service area, not living spaces

Solar panels: Shed roof = ~250 m² unbroken W-facing slope at 10° (~40 kWp, ~82% of south-optimal yield, peak generation in afternoon matching AC load). Hip roof = ~130 m² fragmented across 4 slopes at 30° (~50% of shed capacity). Panels also reduce roof heat by 38% and cool ceiling by 2.8°C (UC San Diego).

Combined benefit: Solar panels generate electricity and reduce roof heat by 38%. The shed roof provides ~250 m² of unbroken west-facing slope for panels, versus ~130 m² on the hip. Combined with Powerlouvre thermal exhaust, this creates a three-layer cooling system: panels shade the roof, the sloped ceiling channels hot air up, and Powerlouvres exhaust it.
6 — Rain Protection & Drainage
Hip Roof

Hip — Rain Drainage

Water drains to all 4 sides · gutters needed everywhere

gutter gutter Water drains to ALL 4 sides
Proposed

Shed — Rain Drainage

ALL water drains West (away from pool) · E side stays dry

heavy gutter dry zone (pool side) ALL water to W — pool deck stays dry
7 — Numbers at a Glance

Hip Roof (Current Design) — 30°

Wall height3.0m (all sides)
Ridge height5.73m
E eave (pool, ~1m ov)~2.42m
W eave (~1m ov)~2.42m
Interior peak5.73m at center
Roof area~340 m²
StructureRidge + hip rafters + purlins
DrainageAll 4 sides
Thermal ventilationNo height differential

Shed Roof (Proposed) — 10°

E wall (high)4.93m
W wall (low)3.26m
E eave (pool, 4m ov)5.64m
W eave (1.5m ov)3.0m
Interior ceiling4.93 → 3.26m slope
Roof area~290 m² (−15%)
StructureSimple wall-to-wall rafters
DrainageWest only
Thermal ventilation1.67m stack + Powerlouvres
8 — Assessment Summary

Shed Roof Advantages

Considerations & Risks

9 — Structural & Cost Impact

Saves Cost

No ridge beamMajor saving
No hip raftersEliminates HRS1/HRS2
Simpler raftersWall-to-wall span
Less roof area−50 m²
No hip framing4 fewer corners

Adds Cost

Taller E wall4.93m × 25m
Wind bracingTaller = more force
Metal roofingDepends on spec
Redesign feesEliya + Yuki
PowerlouvresAlready spec'd

Net Assessment

StructuralSimpler overall
Materials~Neutral
LaborLikely lower
Design reworkSignificant
Long-term valueSolar + cooling ROI
10 — Decision Points for Carlos & Eliya
Key questions before committing:
1. Metal vs tiles — is standing-seam metal roofing acceptable? (required at 10°, could be aesthetic plus for modern look)
2. E wall 4.93m, W wall 3.26m — Carlos noted even 500mm raise is significant scope. Both walls raised. Structural + cost implications?
3. Yuki engineering — ~80% complete on hip roof (S1-05). What's the rework cost/timeline?
4. Powerlouvre placement — high E wall section (above ~3.5m) for thermal exhaust — coordinate with Breezway specs.
5. Solar panel spec — west-facing 10° tilt: get quote from installer. 250 m² available area.
6. Timeline — V5 plans are near-final. Roof type change is fundamental. When is point of no return?

Baan Suriya Chan · 25m × 9.45m, rotated −17° from true North.
Hip roof data from engineering plans S1-05 (Yuki/Dontapo Pechmai) and architectural V4 (Eliya, 12.02.26).
Shed dimensions calculated at 10° pitch, W wall 3.26m, E overhang 4.0m, W overhang 1.5m, W eave 3.0m.
Solar panel heat study: Kleissl et al., UC San Diego, Solar Energy journal.
Powerlouvre specs: Breezway Powerlouvre System.
Stack effect: Architropics.
For interactive solar analysis: Solar Overhang Simulator · Roof Height Visualizer