GENERAL INFORMATION

  • Sector : Residential, Modular
  • Structure : Reinforced concrete, Light wood frame
  • Number of floors : 6
  • Achievement : 2014-2015
  • Work cost : N/A $
  • Area : 80 000 pi²

Un Toit en Réserve - 6 storeys in light-frame wood

 

Project description

Construction of a 6-storey housing cooperative (59 units) in light prefabricated wood frame.  The first of its kind in Quebec since the adoption of section 127 of the Building Act, this wood project is certainly not the last.

 

Inspiration

  • Built on the Champlain Sea deposits, this building required the use of piles, given the low capacity of the soil. The use of wood made it possible to lighten the structure in order to minimize the weight of the building, and thus the cost of the foundations.
  • The lateral strength design of a six (6) storey light timber frame building is a real challenge as the calculation of building deformations must take into account wall rotation due to tilting and bending, which is not the case for a building of four (4) storeys or less. Very strict limits must be observed for inter-storey and cumulative deformations over the entire height of the building. As if that were not enough, the building rests on a liquefiable soil of poor quality, which results in much greater seismic forces being induced to the building, increasing deformations at the same time.
  • The use of shrinkage compensators to minimize the problems caused by shrinkage of wood during its drying phase.
  • In terms of civil engineering, given the presence of a combined network (sewer and rainwater) already at full capacity, the water management design required limiting rainwater discharge to only 30 l/s/ha instead of 50 l/s/ha. Given the small size of the land and the lack of surface parking, the design of the water retention system required several tricks from the design team in order to remain economical, while respecting the City's criteria.
  • Originally designed as a modular construction, but in a context where contractors were not up for the challenge, the project had to be converted to prefabricated panel construction.  
  • But, with hindsight and experience... There are many challenges to add two floors to the usual 4-storey limit.  With the added weight, the load-bearing walls at the bottom become highly loaded and require 2x6 wood studs to be spaced closer, down to 8" c/c and even less.  The carpenters' lack of experience with the additional measures and their reluctance to take these measures seriously were the source of a lot of frustration on both sides.  

Team

Lead Designer /Structure: Mario Payeur, ing., M.Sc. and Vivien Mollard, ing.
Lead/Civil Designer: Kevin D. Below, ing., P.Eng., Ph.D.
Concrete designer: Jean-Philippe Laberge, eng. jr
BIM: Kevin Hennel and Vivien Mollard