Build Without Regrets
Fundamental 03 — The Building Envelope
What actually makes a wall work?
A wall is not simply:
drywall
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studs
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insulation
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siding
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A high-performing building enclosure has several jobs happening simultaneously.
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It needs to manage:
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water
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air
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vapor
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heat
while supporting structure, durability, comfort, and the architectural design.
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Think of the envelope as the boundary between inside and outside
Your roof, walls, windows, doors, foundation, and slabs collectively form the building envelope.
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This boundary influences:
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indoor temperature
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drafts
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condensation
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moisture
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energy use
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acoustic comfort
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indoor air
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mechanical-system demand
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A problem in one layer can create consequences somewhere else.
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The common mistake
Thinking more insulation automatically means a better wall.
Insulation matters.
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But insulation alone cannot compensate for poor:
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water management
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air sealing
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flashing
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thermal-bridge control
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vapor strategy
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window installation
A wall can contain excellent insulation and still perform poorly if air and water are moving through it in uncontrolled ways.
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Four things every enclosure must manage
01 Water
Bulk rain should be drained away from the structure.
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02 Air
Air leakage can affect comfort, energy use, moisture, and pollutant movement.
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03 Vapor
Water vapor moves differently depending on climate, season, material properties, and assembly design.
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04 Heat
Insulation and thermal-bridge control help maintain more stable interior temperatures.
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The important part is not simply having all four layers.
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It's making sure they are continuous.
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Continuity is where buildings often fail
Look carefully at:
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windows
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doors
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roofs
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foundations
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balconies
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cantilevers
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penetrations
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mechanical openings
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transitions between materials
Those are the places where one control layer often stops and another is expected to begin.
Details matter.
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Windows are part of the enclosure too
A high-performance wall with poorly selected or installed windows can still create:
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drafts
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condensation
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overheating
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cold interior surfaces
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water intrusion
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discomfort
Window decisions should consider more than a performance number.
Orientation, shading, placement, installation, views, daylight, ventilation, and comfort all matter.
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Decisions worth making early
Ask:
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Where are the water, air, thermal, and vapor-control layers?
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Are they continuous?
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What happens at windows and doors?
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Where are the major thermal bridges?
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How does the roof connect to the walls?
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How does the wall connect to the foundation?
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How will penetrations be sealed?
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Are the assemblies appropriate for the local climate?
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Questions to ask your project team
Can you show me the continuous air-control layer?
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Where does water drain if it gets behind the exterior finish?
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How are windows tied into the weather barrier?
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Where does insulation become discontinuous?
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How are balconies, overhangs, and structural penetrations handled?
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How does this wall assembly manage drying?
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