TABLE R303.1.3(4)

DEFAULT U-FACTORS FOR SKYLIGHTS

		Frame Type
		Aluminum Without Thermal Break	Aluminum With Thermal Break	Reinforced Vinyl/Aluminum-Clad Wood or Vinyl	Wood or Vinyl-Clad Wood/Vinyl Without Reinforcing
Fenestration Type		Aluminum Without Thermal Break	Aluminum With Thermal Break	Reinforced Vinyl/Aluminum-Clad Wood or Vinyl	Wood or Vinyl-Clad Wood/Vinyl Without Reinforcing
Single Glazing
	glass	U-1.58	U-1.51	U-1.40	U-1.18
	acrylic/polycarb	U-1.52	U-1.45	U-1.34	U-1.11
Double Glazing
	air	U-1.05	U-0.89	U-0.84	U-0.67
	argon	U-1.02	U-0.86	U-0.80	U-0.64
Double Glazing, e = 0.20
	air	U-0.96	U-0.80	U-0.75	U-0.59
	argon	U-0.91	U-0.75	U-0.70	U-0.54
Double Glazing, e = 0.10
	air	U-0.94	U-0.79	U-0.74	U-0.58
	argon	U-0.89	U-0.73	U-0.68	U-0.52
Double Glazing, e = 0.05
	air	U-0.93	U-0.78	U-0.73	U-0.56
	argon	U-0.87	U-0.71	U-0.66	U-0.50
Triple Glazing
	air	U-0.90	U-0.70	U-0.67	U-0.51
	argon	U-0.87	U-0.69	U-0.64	U-0.48
Triple Glazing, e = 0.20
	air	U-0.86	U-0.68	U-0.63	U-0.47
	argon	U-0.82	U-0.63	U-0.59	U-0.43
Triple Glazing, e = 0.20 on 2 surfaces
	air	U-0.82	U-0.64	U-0.60	U-0.44
	argon	U-0.79	U-0.60	U-0.56	U-0.40
Triple Glazing, e = 0.10 on 2 surfaces
	air	U-0.81	U-0.62	U-0.58	U-0.42
	argon	U-0.77	U-0.58	U-0.54	U-0.38
Quadruple Glazing, e = 0.10 on 2 surfaces
	air	U-0.78	U-0.59	U-0.55	U-0.39
	argon	U-0.74	U-0.56	U-0.52	U-0.36
	krypton	U-0.70	U-0.52	U-0.48	U-0.32

Notes for Table R303.1.3(4)
1.	U-factors are applicable to glass and plastic, flat and domed units, all spacers and gaps.
2.	Emissivities shall be less than or equal to the value specified.
3.	Gap fill shall be assumed to be air unless there is a minimum of 90% argon or krypton.
4.	Aluminum frame with thermal break is as defined in footnote 1 to Table R303.1.3(1).