Testing Air, Water, Wind, Forced Entry

Width of the overall glass unit is 1 3/8" top rating in energy efficiency.


Air Resistance (Factor A)

Airtightness is measured by applying 75 pascals of pressure - the equivalent of a steady 25 mph (34 kph) wind - to the outside of the window. Interior air infiltration is then measured in cubic feet per minute per foot of crack length.

Volume of infiltration   Window type
0.002 cu. ft./min/joint ft. A3 fixed, casement and awning windows
0.086 cu. ft./min/joint ft. A3 sliding and hung windows
0.1 cu. ft./min/joint ft. A3 High-end
0.3 cu. ft./min/joint ft. A2 Mid-range
0.5 cu. ft./min/joint ft. A1 Low-end

Water Resistance (Factor B)

Watertightness is measured by projecting the equivalent of 5 U.S. gallons of water per hour per square foot of window surface, the equivalent of 8 in. (200 mm) of rain in 1 hour. Air pressure is increased to simulate winds varying between 35 and 76 mph (57 to 123 kph). Ratings indicate the pressure attained without any interior water leakage.

Wind pressure   Window type
700 pascals 14.6 psf B7 fixed, casement and awning windows
400 pascals 8.4 psf B4* sliding and hung windows
300 pascals 6.3 psf B3 High-end
200 pascals 4.2 psf B2 Mid-range
150 pascals 3.0 psf B1 Low-end

Wind Resistance (Factor C)

This test measures the wind pressure windows can withstand without suffering breakage (structural shattering) or permanent damage (structural deformation).

Wind velocity   Window type
220 mph (350 kph) C5 fixed, casement and awning windows
205 mph (330 kph) C5* sliding and hung windows
180 mph (295 kph) C4 High-end
160 mph (255 kph) C3 High-end
130 mph (210 kph) C2 Mid-range
110 mph (180 kph) C1 Low-end

Forced Entry

This test reproduces the efforts of a well-equipped individual attempting to force entry. The test has three phases. Testers try to force open the window using tools like a knife blade, screwdriver and wire. They then attach a cable to strategic points on the window and apply increasing loads. If the window continues to resist, they use tools again in a third attempt. Windows rated F1 have a locking system, but have not been tested for forced entry. Windows rated F2 have successfully passed the test at level 10. OSTACO windows are rated F2, level 40.

Rating Level Window type
Level indicates the initial load applied to the cables:
F2 Level 40 = 300 lb. OSTACO
  Level 30 = 250 lb. High-end
  Level 20 = 200 lb. Mid-range
  Level 10 = 150 lb. Low-end
F1 Test not required  

Performance Ratings

Casement 3-1/4" A3 B7 C3
Fixed Casement 3-1/4" Fixed B7 C4
Picture 3-1/4" Fixed B7 C4
Single Hung 3-1/4" (Reinforced) A3 B4 C3
Double Hung 3-1/4" (Reinforced) A3 B3 C3
Single Lift-out Slider 3-1/4" (Reinforced) A3 B5 C3
Double Lift-out Slider 3-1/4" (Reinforced) A3 B4 C2
Core Plus Casement 4-9/16" A3 B7 C5
Core Plus 4-9/16" Fixed Casement Fixed B7 C4
Core Plus 4-9/16" Picture Window Fixed B7 C4
Core Plus 4-9/16" Single Hung  (Sloped Sill) A3/Fixed           B3 C5
Core Plus Double Hung 4-9/16" A3 B5 C3
Core Plus 4-9/16" Single Lift-out Slider A3/Fixed           B2 C3
Core Plus 4-9/16" Double Lift-out Slider A3        B4 C5

** All of our screens have a rating of S1.
** All of our windows have a forced entry rating of F10