CSA A440S1, the Canadian supplement a US report misses

CSA A440S1 is published by the CSA Group as a National Standard of Canada and is written to be used in conjunction with the North American Fenestration Standard. The current edition is the fifth, CSA A440S1:25, published on 1 January 2025. It supersedes the fourth edition, CSA A440S1:19, which had been reaffirmed in 2022.

The pairing matters. The fifth edition is written against AAMA/WDMA/CSA 101/I.S.2/A440:22, so a supplement and a base standard from different generations are not interchangeable. A report citing the 2019 supplement beside the 2022 base standard is citing two documents that were not written for each other.

The scope is narrow on purpose. The Canadian supplement is applicable to Canada only, and its requirements are in addition to the base standard, not a restatement of it. What it adds is the load side: simplified methods for calculating the minimum performance levels for wind, water penetration and snow, plus the environmental data for individual locations that a specifier in Canada actually needs.

Fenestration Canada, the industry body that publishes the compliance advisory for imported products, states the position in a form that leaves no room. A test report to a European, British or ISO standard does not qualify a product for use in Canada. A NAFS test report conducted in the United States that does not include the requirements of the Canadian supplement does not qualify either.

That is the sentence to read before a quotation is accepted. A supplier holding a genuine NAFS report from a United States laboratory has cleared the base standard and has not cleared Canada. The two facts sit side by side without contradiction, and the gap between them is one document.

The practical consequence is a submittal that looks complete and is not. The report is real, the laboratory is accredited, the performance class and grade are stated, and the building official still has nothing to accept because the air leakage levels, the exfiltration test and the water resistance figure on the report are the American set.

The base standard measures air leakage under ASTM E283 at a pressure difference of 75 Pa and reports it as a rate per unit of area. The supplement takes that measurement and splits it. Infiltration and exfiltration are both tested, because air moves in both directions across an envelope and because a gasket that seals one way does not necessarily seal the other.

Operable products then carry one of two levels. A2 is the minimum for an operating window or door at 1.5 litres per second per square metre at 75 Pa. A3 is the tighter level at 0.5. Fixed products carry a separate requirement of 0.2, which is stricter than either operable level because a fixed unit has no reason to leak at all.

Against that, the American route applies a single figure of 1.5 to the R and LC classes without distinguishing an operable unit from a fixed one. A fixed window that meets the American requirement at 1.5 is an order of magnitude away from the Canadian fixed figure of 0.2, which is the single most common reason a report transfers badly.

The American route expresses water resistance as a percentage of design pressure: 15 percent for the R, LC and CW classes and 20 percent for AW, with a cap on the test pressure at 580 Pa. The supplement raises that cap to 720 Pa and reports the tested resistance in pascals instead of leaving it to be inferred from a class.

The larger change is where the number comes from. The supplement carries environmental data for locations across Canada, and the required water resistance is read against the driving rain wind pressure at the municipality, adjusted for terrain and for height above grade. In some places the resulting figure is above 15 percent of the design pressure, and in some places it is below. Which is why a specification that relies on a flat percentage of design pressure, as the American path allows, will not always land on the right product.

The failure criteria are also stricter. The Canadian test looks at whether water remains in an undrained framing cavity, not only at whether water reaches the interior face. A unit can pass a spray observation and still hold water where it will find its way in later. The tested figure covers the unit as it leaves the factory; the joint between frame and wall is built on site and sits outside that number.

Operating force is a small clause with a counter-intuitive effect. For sliding doors, the Canadian requirement applies the R and LC force limits to all four performance classes: 135 newtons to initiate motion and 90 newtons to maintain it. The American route applies higher limits to the CW and AW classes, at 180 and 115 newtons.

So a heavy sliding unit specified to the CW class is allowed to be harder to open in the United States than it is in Canada. A product developed against the American CW figures can be outside the Canadian limit without any of the structural numbers changing, which makes this the clause most likely to be discovered late.

The supplement requires the tested properties to be reported on a non-permanent product label, and the list is longer than the American label. The design pressure appears as a positive and a negative figure, the water penetration resistance test pressure appears as a value in pascals, and the air infiltration and exfiltration level appears as A2, A3 or Fixed.

Forced entry is part of the same package. A product carries a Canadian label only when it meets the applicable requirements of the base standard and the supplement together, forced entry included. A label that names the class and grade but stops short of the air level is an incomplete label, and an incomplete label is what a final inspection reads.

The fifth edition is not a reprint. The calculation of specified wind load now includes a 20 metre reference height, and the reference height itself is tied to the exposure factor. The marking requirements for the performance rating were updated, which is the clause that governs what the label shows. Table A.1, the climate design data for selected locations in Canada, was brought into line with the 2020 edition of the National Building Code of Canada.

There is also a note in the annex on climate change and its effect on design loads, which is unusual in a product standard and worth knowing about when a building is specified for a long service life.

One caution sits in the scope. The simplified wind calculation applies only to buildings on level terrain with a slope no greater than one in ten. A site on a hill, an escarpment or a steeper slope falls back to the full procedure in the National Building Code, and the simplified route can produce a higher figure than the code procedure does. A specification that quotes the simplified number without checking the terrain is quoting a number for a different site.

None of that is unusual to ask for, and all of it is checkable. The honest position for a supplier is that the report either exists for the configured model or it does not, and a schedule that says which is worth more than one that implies the answer.

• The test report naming AAMA/WDMA/CSA 101/I.S.2/A440:22 together with CSA A440S1:25, not one without the other.
• The air infiltration and exfiltration level the unit was tested to, stated as A2, A3 or Fixed, with the tested rate at 75 Pa.
• The water penetration resistance test pressure in pascals, matched to the driving rain wind pressure for the municipality.
• The operating force measured on the sliding or hinged unit, read against the Canadian class limits rather than the American ones.
• The label content, including the positive and negative design pressure and the air level, as it will appear on the unit.
• The terrain assumption behind the wind figure, where the simplified calculation was used.
• Confirmation of which edition of the base standard and which edition of the supplement the report was written to.