CLT: Managing Air and Heat

 

CLT Panels Rarely Remain Airtight

Pressure differences cause air movement across the building enclosure. Movement is caused by a pressure differential between the inner and outer enclosure surfaces, typically attributed to a combination of wind, the stack effect, and mechanical ventilation systems.

 

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Air Barrier Must be Continuous

A continuous air barrier is a requirement of both the 2018 IECC1 and the National Building Code of Canada to control air flow across the enclosure. Limiting the air flow across the CLT enclosure, both inward and outward, has significant performance benefits such as:

  • Reduced energy consumption for building heating and cooling
  • Improved occupant comfort by limiting drafts
  • Reduced risk for interstitial condensation from moisture-laden air
  • Minimized transfer of other undesirable substances such as sound, smoke, fire, and pollutants

Durability

An air barrier must be durable to avoid damage that could affect its intended performance during construction and throughout its service life.

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System of Materials is Required

The air barrier is not a single component or material but rather requires a system of materials, components, and assemblies that provide continuous air control throughout the building enclosure.

 

VaproShield Membranes Improve Air Barrier Continuity

VaproShield’s sheet membrane products can improve continuity of the air barrier by resisting lateral air movement between the membrane and the CLT panel.

Accessory Products for Transitions, Interfaces, Rough Openings, Penetrations

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Heat Management

Low Thermal Conductivity

CLT panels contribute to the assembly’s thermal performance because wood has a relatively low thermal conductivity when compared to other common structural materials such as concrete and steel.

Insulation Placement

It is typically desirable to locate insulation outboard of the CLT to keep the CLT panel closer to the indoor temperature, minimizing condensation risk and limiting temperature and relative humidity fluctuations that may result in dimensional cycling of the CLT.

Key Factors

Selection and placement of the insulation will depend on numerous factors such as climate zone, national and local codes and cladding attachment systems. 

Membrane Compatibility

VaproShield membranes are compatible with mineral wool and rigid insulation.  View the Technical Bulletin on Fastener Penetration Testing or Details showing a variety of insulation placement conditions.

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  1. WrapShield SA Self-Adhered WRB/Air Barrier
  2. Continuous Semi-Rigid Insulation
  3. Continuous Rigid Insulation
  4. RevealShield SA Self-Adhered WRB/Air Barrier for Open Joint Systems
  5. Cladding

 

VaproShield Membranes Offer Solutions

VaproShield’s sheet membranes are highly vapor permeable, simultaneously managing bulk water while allowing for some drying of underlying materials.

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CLT Design Guide

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Wall Details

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Roof Details

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Prefabrication