Are holes in perforated soffit vinyl panels counted as vent openings?

[sunyaer]

This is from Ontario building code:

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9.19.1.2. Vent Requirements
....
(3) Required vents are permitted to be roof type, eave type, gable-end type or any combination of them, and shall be
distributed,
(a) uniformly on opposite sides of the building,
(b) with not less than 25% of the required openings located at the top of the space, and
(c) with not less than 25% of the required openings located at the bottom of the space.

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For the requirement of (c), are holes in perforated soffit vinyl panels counted as vent openings? And how to calculate the area of holes?

 

[ICE]

From California Residential Code:
Ventilation openings shall have a least dimension of 1/16 inch (1.6 mm) minimum and 1/4 inch (6.4 mm) maximum. Ventilation openings having a least dimension larger than 1/4 inch (6.4 mm) shall be provided with corrosion-resistant wire cloth screening, hardware cloth, perforated vinyl or similar material with openings having a least dimension of 1/16 inch (1.6 mm) minimum and 1/4 inch (6.4 mm) maximum.

 

[sunyaer]

Any input as per Canadian / Ontario building code? And how to calculate the area of holes of perforated soffit vinyl panels if they can be counted as opening as per 9.19.1.2. (3)(c) of Ontario building code?

 

[ICE]

I am not familiar with the Canadian codes. The panel manufacturer should be able to provide the net area of the perforations.

 

[e hilton]

And how to calculate the area of holes

High school geometry. A=pi*(radius squared).

 

[sunyaer]

High school geometry. A=pi*(radius squared).

I am more interested in knowing if there is any code provision on the calculation, rather than the mathematical area.

 

[ICE]

R806.2 Minimum vent area. The minimum net free ventilating area shall be 1/150 of the area of the vented space.
Exception: The minimum net free ventilation area shall be 1/300 of the vented space provided both of the following conditions are met:
1. In Climate Zones 14 and 16, a Class I or II vapor retarder is installed on the warm-in-winter side of the ceiling.
2. Not less than 40 percent and not more than 50 percent of the required ventilating area is provided by ventilators located in the upper portion of the attic or rafter space. Upper ventilators shall be located not more than 3 feet (914 mm) below the ridge or highest point of the space, measured vertically. The balance of the required ventilation provided shall be located in the bottom one-third of the attic space. Where the location of wall or roof framing members conflicts with the installation of upper ventilators, installation more than 3 feet (914 mm) below the ridge or highest point of the space shall be permitted.

 

[tmurray]

They are the start of the required openings, but the openings are usually continued through the attic through the use of attic ventilation baffles, sometimes referred to as "true vents", but that is a brand name. Without these, insulation can block the ventilation at the eaves.

 

[Inspector Gadget]

They are the start of the required openings, but the openings are usually continued through the attic through the use of attic ventilation baffles, sometimes referred to as "true vents", but that is a brand name. Without these, insulation can block the ventilation at the eaves.

As the above post indicates, the bottleneck on a soffit-ridge or soffit-gable venting system is the vent at the insulation pinch point, if there is one. In most cases, soffit-venting every truss cavity provides about three times the required minimum, based on the calculations I have done.