Question

In combustible construction, where there is usable space both above and below a floor/ceiling assembly, draft stops shall be installed so that the area of the concealed space does not exceed ______ square feet.

1) 100
2) 150
3) 200
4) 250

Answer 1

To calculate the mass of air in a house with a floor area of 150 m² and a ceiling height of 2.5 m, multiply the volume (375 m³) by the air density (1.2 kg/m³), resulting in 450 kg of air. This mass, equivalent to 450 bags of rocks, cannot be lifted all at once by a person. The provided options related to draft stops in combustible construction are not applicable to this calculation.

Step-by-step explanation:

To calculate the mass of air in a house, we can use the density of air and the volume of the house. At room temperature and sea level, the density of air is approximately 1.2 kg/m³. The volume of a typical house with a floor area of 150 m² and a floor-to-ceiling height of 2.5 m is calculated as follows:

Floor area × height = 150 m² × 2.5 m = 375 m³.

To find the mass of air, multiply the volume by the density of air:

375 m³ × 1.2 kg/m³ = 450 kg.

This amount of mass is equivalent to 450 bags of rocks, each weighing 1 kg, which would be impossible for a person to lift all at once. Draft stops in combustible construction don't specifically relate to the calculation of the mass of air, but are mentioned in building codes and regulations, which address the limitation on the area of concealed spaces to prevent fire spread.