Loads on Buildings & Occupants
Translate conditions into physical loads on the building and exposures for occupants, creating the bridge from context to technical requirements.
Builds on: P2 (environmental conditions) · Leads to: P4 (failure mechanisms), P5 (system interactions) · Cross-series: A3 Permits, Fees & Taps
P/A bridge: Which load assumptions should plan reviewers require up front to avoid costly redesign and field changes later?
Core Concepts
Loads are how conditions act on buildings. Can name dominant loads for common local scenarios.Occupant exposure matters as much as material stress. Can connect IAQ/comfort outcomes to load management.Reducing peak loads simplifies controls. Can identify strategies that reduce peak stress, not just treat symptoms.
Load Categories
Structure + forces
Snow + wind: roof and lateral loads; drift/edge effectsSoil movement: settlement, expansive soils, drainageUse loads: decks, stairs, guardrails - where failures become injuries
Heat + energy
Cold snaps: peak heating demand and comfort risk at the marginsSolar + internal gains: overheating and glare (even in cold climates)Plug loads: real-world energy use that defeats "modeled" expectations
Moisture + behavior
Occupant moisture: showers, cooking, plants, humidifiers, laundry - short peaks matter as much as steady loadsOccupant exposure: smoke days, cooking peaks, attached garage pressure, bedroom CO2, indoor moisture from behavior
PF: Structural/Mechanical (C1), Thermal (C2), Moisture (C3), Air Quality (D1), Thermal Comfort (D2)
Worked Example: Wind-Driven Snow
Wind-driven snow at a roof-wall transition creates a drift load + meltwater load. This translates into: flashing/ice protection check, attic air sealing check, and structural load verification. In Northern Colorado, add expansive soil movement (foundation cracks create water/air paths) and smoke-day filtration load (uncontrolled leakage becomes an IAQ failure).
Where Things Go Wrong
1. "The bonus room is always cold"
Peak load in an exposed zone is higher than expected - comfort complaints and endless tweaking
Root: peak heating load underestimated; Check: verify insulation continuity, confirm supply airflow reaches room
2. "It's efficient, but it overheats"
High solar gain + internal gains - summer discomfort despite good insulation
Root: gains not managed; Check: review glazing orientation and shading, check cooling capacity
3. "Humidity spikes and musty smell"
Short, intense moisture events + limited ventilation strategy - recurring mustiness
Root: moisture load not anticipated; Check: confirm ventilation rate and dehumidification capacity