Condensation Building Codes & Rules

• Part of NCC condensation management requirements by Climate Zones^{NCC 2025 Vol 1, F8D3}
• Pliable Membranes or Sarking-type Materials
• Form part of building envelope
• Vapour permeance as per table below

Breathing

Handwashing

Managing Condensation - SOU Building Class 2 or 4

• Minimises moisture accumulation within the structure^{NCC 2025 Vol 1, F8F1}
• Adverse wellness & health issues^{NCC 2025 Vol 1, F8P1}
• Upper respiratory symptoms
• Cough & wheezing
• Severe asthma attacks
• TAS Variation^{NCC 2025 Vol 1, F8P1 (TAS)}
• For cool climates, refer to 'Condensation in Buildings Tasmanian Designers' Guide'

Importance of Thermal Breaks^{Industry Recommendation}

• To reduce thermal bridging that creates an immediate way for heat & cold to reach interior surfaces
• Thermal bridges may include windows & doors
• Metal wall frames
• Methods to create Thermal Breaks
• Install insulating strips between metal frames & cladding
• Use insulated glazing units eg. double or triple glazing
• Use thermally-broken aluminum, uPVC or timber frames, instead of highly conductive metals

Indoor Condensation Factors^{ABCB Condensation in Buildings}

• Air leak pressures shifting through interior linings & gaps in
• Light fittings, switches, & power outlets
• Pipe penetrations
• Around doors & windows
• Activity Load such as
• Cooking & dishwashing
• Clothes drying & soaking
• Bathing, showering
• Unflued heating
• Metabolic Load such as
• Breathing & transpiration from the skin
• Air Movement & Ventilation

Building Sealing^{ABCB Condensation in Buildings}

• To improve building sealing is an easy and inexpensive approach to reduce energy expenses, increase comfort, and improve air quality
• Carefully consider the building envelope, materials, & construction

Suspended Flooring^Informative

• Rotting Floor Timber
• Excessive Moisture if Concrete Floor
• Damp & mould forming

Earth Coupled Slab Flooring^Informative

• Absorbing summer heat or cold winter loads
• Excessive Moisture on Concrete Floor

Wall & Floor Damp & Mould

Wall & Ceiling

Damp & Mould

Shower

Insulating Metal Pipes in Cold Climate^{Industry Recommendation}

• Reduces heat loss
• 2° to 4°F increase in water temperature, as compared to uninsulated pipes
• Allows for lower temperature setting
• Mitigates risk of frozen pipes
• Some options may be to utilize
• Pipe sleeve
• Heat tape
• Heat cable

External Walls Construction^{NCC 2025 HP, 10.8.1}

• Installs membrane or sarking
• With the minimum vapor permeance value according to the location
• Cavity drain & ventilation for external walls without vapour barrier
• Cavity positioned between the cladding and the external side of primary insulation layer
• ≥ 18mm wide wall cavity
• ≥ 1000 mm²/m top & base cavity openings per wall
• Cavity drain at the base even for multi-storey buildings
• To Comply with AS 4200.1 & AS 4200.2

Exhaust Systems^{NCC 2022 HP, 10.8.2}

• Exhaust via shaft or duct to outdoor air
• Exhaust flow rate
• ≥ 25 L/s for sanitary compartments
• ≥ 40 L/s for kitchen or laundry
• Comply with NCC Condensation Management

Managing Condensation - SOU Building Class 2 or 4

• Minimises moisture accumulation within the structure^{NCC 2022 Vol 1, F8F1}
• Adverse wellness & health issues^{NCC 2022 Vol 1, F8P1 TAS}
• Upper respiratory symptoms
• Cough & wheezing
• Severe asthma attacks
• TAS Variation^{NCC 2022 Vol 1, F8P1}
• For cool climates, refer to 'Condensation in Buildings Tasmanian Designers' Guide'

Roof Ventilation^{NCC 2022 HP, 10.8.3}

• For Climate Zones 6, 7, & 8
• ≥ 20mm gap between insulation & sarking
• ≥ 1.14 µg/N.s vapour permeance
• Comply with NCC Condensation Management

Heat, Air & Vapour

from the Inside

Warm Weather Vapour Barrier on External Walls^{NCC 2022 HP, 10.8.1 (2)}

• ≥ 0.143 µg/N.s vapour permeance in Climate Zones 4 & 5
• To comply with AS 4200.1 & AS 4200.2

Glass Fog

& Mist

Wall & Ceiling

Damp & Mould

Cold Weather Vapour Barrier on External Walls^{NCC 2022 HP, 10.8.1 (2)}

• ≥ 1.14 µg/N.s vapour permeance in Climate Zones 6, 7 & 8
• To Comply with AS 4200.1 & AS 4200.2

Cooking

Weephole Cavity Drainage

Damp, Mould &

Ponding on Eaves

Indoor Condensation Factors^{ABCB Condensation in Buildings}

• Air leak pressures shifting through interior linings & gaps in
• Light fittings, switches, & power outlets
• Pipe penetrations
• Around doors & windows
• Activity Load such as
• Cooking & dishwashing
• Clothes drying & soaking
• Bathing, showering
• Unflued heating
• Metabolic Load such as
• Breathing & transpiration from the skin
• Air Movement & Ventilation

Building Sealing^{ABCB Condensation in Buildings}

• To improve building sealing is an easy and inexpensive approach to reduce energy expenses, increase comfort, and improve air quality
• Carefully consider the building envelope, materials, & construction

Dishwashing

Clothes Washing

& Drying

Unflued

Heating

Slippery Floor

Rotting Roof Timber

Breathing

& Transpiration

Handwashing

Breathing

Wall & Floor Damp & Mould

Heat, Air & Vapour

from the Outside

Importance of Thermal Breaks^{Industry Recommendation}

• To reduce thermal bridging that creates an immediate way for heat & cold to reach interior surfaces
• Thermal bridges may include windows & doors
• Metal wall frames
• Methods to create Thermal Breaks
• Install insulating strips between metal frames & cladding
• Use insulated glazing units eg. double or triple glazing
• Use thermally-broken aluminum, uPVC or timber frames, instead of highly conductive metals

Shower

Suspended Flooring^Informative

• Rotting Floor Timber
• Excessive Moisture if Concrete Floor
• Damp & mould forming

Earth Coupled Slab Flooring^Informative

• Absorbing summer heat or cold winter loads
• Excessive Moisture on Concrete Floor

Mould Index

• Allowable risk for condensation^[1][2]

Mould Index

NCC 2022 V1

NCC 2022 Vol 1, F8V1

NCC 2022 Vol 2, H4V5

NCC 2022 Vol 1, F8V1

NCC 2022 Vol 2, H4V5

Industry Recommendation