Expertise Report (part 4 of 4)

Stéphanie Landry Poirier

Wednesday, 22 January 2020

(For complete explanation of the study and description of the building, please refer to the first article of this serie).

In this last part (4 of 4), we will discuss the economy which is at the level of the floor system and joists. By reducing the weight of the floors, the joists will necessarily be less loaded. This load reduction would reduce the height, the grade of wood or the number of beams.

For joists with a span of less than 20', the economy is mostly in lumber grade. However, for spans of more than 20', a decrease in the height of the joists would be conceivable. This decrease in height can lead to significant savings in the building envelope (insulation, siding, wood, etc.). For example, for a 6-storey wooden building with 28-foot joists, the building would be 10" lower. Finally, for the same price, joists with a longer span would also be possible.

In conclusion, the use of Fermacell dry flooring boards would allow a potential reduction of 5% in costs for foundations. For structural slabs, the potential cost reduction would range from 2.77% to 6.19%, depending on the thickness of the slab chosen. Reducing weight by using Fermacell product could also impact other elements of the structure such as load-bearing walls, wood beams and timber columns. The speed of execution could be increased since Fermacell dry flooring boards do not need drying cure. By the same token, moisture input into the building would be limited because the flooring boards are dry when they arrive on site.

This analysis is not a guarantee that savings can be replicated in all projects or situations and does not replace the expertise of a structural engineer.

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