FIRE:

The rule of thumb for 1D systems is that individual supports must only be designed to retain their structural integrity (R). Furthermore, the behavior of timber structural elements in fire is greatly influenced by the proportion of surface to cross section and the densities of various woods. As a result, for 1D system members to meet potential fire requirements, their cross-section may be enlarged if exposed timber is desired. Alternatively, the member can be cladded in a non-combustible material (typical one or two layers of 16mm or greater fire-resistant gypsum).

For all system types, most connectors are fabricated from steel and the performance of steel in high temperatures deteriorates. Typically, the connectors will be protected within a fire board or within a floor and wall assembly.

The rules of thumb stated for residential 2D systems can also be applied to educational typologies. However, it is important to note that educational typologies typically require a fire resistance of 30-60 minutes, depending on overall building height and footprint. For example, the Wood Innovation and Design Centre requires 60 minutes and is considered building class 5, while the European Frankfurt School requires a 30-minute resistance rating and is considered building class 3 (Kaufmann, et. al, 2018). Often, educational typologies will utilize sprinkler systems to help attain their fire resistance rating, while adding additional layers of gypsum to walls, floors and ceilings.

The rules of thumb for fire and 3D timber systems are like that of the 2D rules of thumb. However, in both residential and educational cases, the double stacking of floors and walls should be considered. 7 The double stacking of CLT panels increases the fire resistance rating of the project and results in the potential for thinner CLT Panels for each module.

• As a result of Glue laminated timber being rarely used in multi-storey residential units, there are no specific fire rules of thumb for this condition. As stated previously, it is recommended to utilize 2D, 3D or a combination of both for residential units.

• The required corridors and staircases must be kept free of fire loads by means of paneling with non-combustible cladding.
• If the ceiling and floor are made of visible wood, the walls should be paneled with a noncombustible material, or if t wo walls are not lined, then either the ceiling or floor may be made of visible timber
• In principle, increased requirements for fire resistance can be compensated by the following measures:
  • Increase the thickness of the CLT element
  • Increase the number of layers of the CLT element
  • Clad CLT member with fire rated gypsum board

• For 3D systems, follow the rules of thumb stated for 2D systems. However, for 3D systems:
• The double stacking of CLT panels increases the fire resistance rating of the project
• Resulting in the potential for thinner CLT Panels
• Important to keep in mind of the double stacking of floor to ceiling and wall to wall