NAFS stands for the North American Fenestration Standard and sets the minimum performance standard on the sliding doors.

NAFS sets minimum standards for air tightness, water tightness, wind resistance, forced entry resistance and ease of operation.

NAFS uses performance grades for products. To determine the performance grade needed in a particular location in Canada see the Performance Grade Calculator at

The National Building Code of Canada and most provincial building codes require that sliding patio doors meet NAFS-08 specifications. Each patio door product line must be tested by an independent laboratory and meet minimum performance standards in four areas critical to performance: air tightness, water tightness and wind resistance and forced entry resistance. The results of the tests are then published. Consumers should ask for and be shown these test results.

Air Tightness (or Air Leakage) Test

This test is performed at a test pressure that represents a 40 km/h wind. The patio door leakage is measured in liters per second per square meter. 1.5 l/s/m2 is the maximum leakage that is allowed with the A3 level being 33% of the A2 maximum. (SHOW PATIO DOOR AIR LEAKAGE CHART)

Water Tightness (or Water Leakage) Test

The water leakage test is performed by spraying the patio door with a constant stream of water, raising the test pressures to simulate increasing wind loads, and observing if any water gets inside the patio door. Each pefromance grade represents wind load starting at 58 km/h and rising incrementally. Because different parts of Canada have different wind loads and these have been measured and published, the National Building Code requires different minimum levels for patio doors in different regions. (SHOW PATIO DOOR WATER LEAKAGE CHART)

Wind Load Deflection and Structural Tests

These tests measures the deflection and permanent damage of the patio door components under increasing pressures, which represent higher wind loads. Check the performance grade calculator at to determine the grade needed in any location in Canada.