Outdoor Intake - Clearance to Grade

[Admin]

The home inspectors are now enforcing Ontario Building Code Article 9.32.3.12 which says an outdoor air supply must be 450mm (17.75") from grade.

If you come across an inspector trying to enforce this rule use this argument.

Clause 4.1.2 of the B149.1-15 Gas Code says,

When a specification or document referenced in Clause 2 contains a requirement that conflicts with a requirement in this Code, the requirement in this Code shall govern.

Clause 2, of the B149.1-15 Gas Code, references to the National Building Code of Canada.  (NRC - National Research Council Canada - National Building Code of Canada). 

Clause 8.3.6 of the B149.1-15 Gas Code says,

An air-supply inlet opening from the outdoors shall be located not less than 12 in (300 mm) above the outside grade level.

Therefore our Gas Code trumps the Building Code and only a 12" clearance is required to grade.

[Porcupinepuffer]

The only other issue is whether the inspector is smart enough to also look in the manufacturers manual. I find the manual for just about every appliance always states a foot above the highest anticipated snow level, which would mean being well above 2'.

[Admin]

I was referring more to a 4" outdoor air supply feeding a single pipe water heater over 50,000 BTU's.  We can snorkel any furnace vents easily but you would have to install an external boxed vent outside to raise the 4" outdoor air supply.  This is what I wanted to avoid doing.

That's a good point about the furnace intake though.  Clause 4.1.4 was revoked and replaced.

OLD

4.1.4 - Where a conflict exists between the manufacturer's certified installation instructions and this Code, the requirements of this Code shall prevail unless otherwise approved.

NEW

4.1.4 - Where a conflict exists between the manufacturer's certified installation instructions and this Code, the most stringent of the two shall prevail.