9.19.1.2. Vent Requirements - Flat Roofs

 9.19.1.2. Vent Requirements - Flat Roofs

#Purlins at least 38 × 38 mm (2 × 2 in. nominal) are required to vent flat roofs where the #joist spaces are not individually vented to permit the venting of all spaces (Figure 9.19.-4).

Quoted from Illustrated Users' Guide - NBC2015

#flatroof

9.19.1.2. Vent Requirements

 9.19.1.2. Vent Requirements 

This Article requires sufficient #vent area to transfer to the exterior any #moisture that may collect in roof spaces before it can create problems. Vents not only reduce the amount of winter moisture accumulation, but also allow the roof or #attic space to dry out more quickly in the spring when the temperature rises to a level that might initiate wood decay. In low-sloped roofs, the roof #sheathing is closer to the source of moisture leakage from the space below, and #condensation and frost build-up can occur before the moisture escapes through the roof vents. Therefore, greater vent area is required for such roofs, both to reduce moisture build-up and to hasten subsequent spring drying. 

The distribution of vents on opposite sides of a roof is intended to encourage #cross-ventilation, while top and bottom distribution is intended to take advantage of convection currents to move heated air to the highest part of the roof to escape. If there is no common #attic space (e.g., flat roofs, cathedral ceilings) and there is no interconnection between joist spaces, the only way the roof can be effectively vented is by venting each #joist space. If the vents allow the entry of snow or rainwater, this will add to the moisture load and the risk of problems previously noted.

Quoted from Illustrated Users' Guide --NBC2015

#roofspace #roofvent #crossventilation

9.19.1.1. Required Venting

 9.19.1.1. Required Venting 

This Article requires that roof #venting provide a means for allowing #moisture that may have found its way into an #attic or roof space to escape to the exterior. Excess moisture resulting from winter #condensation can raise the moisture level in such spaces to the point where wood can begin to decay. Water leakage into the conditioned space below may also occur when the winter #frost and #ice build-up melts.

Quoted from Illustrated Users' Guide -- NBC2015

9.15.4.10. Interior Masonry Walls

 9.15.4.10. Interior Masonry Walls

This Article points to the requirements in NBC Section 9.20. for interior masonry walls acting as foundation# walls so that they are constructed to have adequate strength to support anticipated loads. 

The minimum #width for an interior loadbearing masonry# wall depends on the spacing of its lateral support. Such walls must be laterally supported by floor or roof construction, or by intersecting masonry walls or #buttresses. The maximum spacing of such supports can be no greater than 20 times the wall thickness, as illustrated in Figure 9.15.-18 (NBC Article 9.20.10.1.).

#masonrywall #loadbearing #lateralsupport

Quoted from Illustrated Users' Guide-NBC2015