Superdek® Technical Information

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Design considerations

The minimum roof pitch for Superdek is two degrees (1 in 30). The 762mm coverage of Superdek provides easy handling and installation. Superdek roofing is subject to thermal expansion, particularly on darker colours. The maximum length before an expansion joint is required is 24 metres for lighter colours, and 16 metres for darker colours.

Material Specifications

Material Specifications
Material Properties	Finish	0.35 BMT	0.42 BMT	0.48 BMT
Total Coated Thickness (TCT) mm	Zinc/alum	0.40	0.47	0.53
Total Coated Thickness (TCT) mm	Colour	0.43	0.50	0.56
Mass (kg / linear metre)	Zinc/alum	2.74	3.26	3.70
Mass (kg / linear metre)	Colour	2.79	3.32	3.76
Mass (kg / square metre)	Zinc/alum	3.60	4.28	4.86
Mass (kg / square metre)	Colour	3.67	4.35	4.93
Yield (square metre / tonne)	Zinc/alum	277.9	233.8	205.9
Yield (square metre / tonne)	Colour	272.3	229.8	202.8
Tensile Strength (MPa)	Zinc/alum & Colour	550	550	550
Width Coverage (mm)	Zinc/alum & Colour	762	762	762
Sheet Tolerances (mm)	Length & Width	±5 ±2	±5 ±2	±5 ±2
Minimum Roof Pitch	Zinc/alum & Colour	N/A	2˚	2˚

Spans

Spans are determined by wind speeds for non-cyclonic areas. For domestic applications, the pressures and spans are based on a maximum: eaves height of six metres, roof pitch of 35 degrees and total roof height of 8.5 metres. For commercial and industrial applications, tables are based on a maximum overall height of ten metres and a 500 year design return period.

Roofing calculations are based on Cpe=-0.9 and Cpi=0.2, walling is based on Cpe=-0.65 and Cpi=0.2. A local pressure factor, Kl=2.0 has been used for all roofing and walling spans for both strength and serviceability limit states. Roof spans allow for loads incidental to maintenance.

All pressures have been determined assuming the wind loading in any direction is not affected by topography. The following shielding factors have been used for each of the terrain categories: Category 3 = 0.85, Category 2.5 = 0.95, and Category 2 = 1.

The carport and verandah spans only apply to structures not enclosed by peripheral walls. Spans are based on Cpn=-0.9 and Kl=1.5 applied over the entire span, and are suitable for all span types. Loads on supporting purlins may limit these spans.

Stratco can provide additional engineering advice if any design parameters vary from those above.

Spans (mm)
BMT	Application	Span Type	N1 (W28)	N2 (W33)	N3 (W41)	N4 (W50)
0.35 mm	Walling	Single	1700	1700	1600	1450
		End	2200	2200	2000	1550
		Internal	2500	2500	2250	1700
0.42 mm	Roofing	Single	1150	1150	1150	1150
		End	1350	1350	1350	1350
		Internal	1900	1900	1900	1500
	Walling	Single	2350	2100	1850	1700
		End	2850	2550	2250	1700
		Internal	3000	3000	2600	1950
0.48 mm	Roofing	Single	1700	1700	1700	1500
		End	1900	1900	1900	1500
		Internal	2600	2600	2350	1800
	Walling	Single	2800	2400	2000	1950
		End	3200	2950	2550	2050
		Internal	3300	3300	2900	2250
The values are determined by wind speeds for non-cyclonic areas and are for use with steel supports with a minimum thickness of 0.75mm, G550.

Maximum Recommended Spans

Maximum Recommended Spans (mm)
Span Type	Roofing (BMT)		Walling (BMT)
	0.42 mm	0.48 mm	0.35 mm	0.42 mm	0.48 mm
Single Span	1150	1700	1700	2350	2800
End Span	1350	1900	2200	2850	3200
Internal Span	1900	2600	2500	3000	3300
Un-stiffened Overhang	200	250	150	200	250
Stiffened Overhang	300	350	300	300	350
Roofing spans are limited, based on typical maintenance foot traffic. Walling spans are based on N1 (W28) wind loading. The values are for use with steel supports with a minimum thickness of 0.75mm, G550.

Domestic Carport / Verandah Spans

Domestic Carport / Verandah Spans (mm)
Wind Classification	Base Metal Thickness
Wind Classification	0.42 mm	0.48 mm
N1 (W28)	2400	2700
N2 (W33)	2400	2700
N3 (W41)	1900	2100
N4 (W50)	1500	1700
The values are for use with steel supports with a minimum thickness of 0.75mm, G550.

Wind Load Conversion

For domestic applications use the appropriate wind classification for the area. To read the span tables for commercial and industrial applications, select the region and category for the area, then convert it to the correct classification using table below.

Wind Load Conversion
Wind Classification (Domestic)	Region & Category (Commercial / Industrial)
N1 (W28)	Reg A, Cat 3
N2 (W33)	Reg A, Cat 2.5 - Reg B, Cat 3
N3 (W41)	Reg A, Cat 2 - Reg B, Cat 2.5
N4 (W50)	Reg B, Cat 2

Wind Capacities

Wind Capacities (kPa)
BMT	Span Type	Limit State	900	1200	1500	1800	2100	2400	2700	3000	3300	3600
0.35 mm	Single	Serviceability	2.19	1.68	1.36	1.06	0.76	0.45	-	-	-	-
	Single	Strength	6.64	4.83	3.06	2.61	2.14	1.67	-	-	-	-
	End	Serviceability	2.45	2.08	1.86	1.64	1.30	0.95	0.61	0.27	-	-
	End	Strength	6.50	5.00	3.75	2.50	2.17	1.83	1.50	1.17	-	-
	Internal	Serviceability	3.68	2.68	2.10	1.53	1.33	1.14	0.94	0.75	-	-
	Internal	Strength	6.67	5.33	4.21	3.08	2.69	2.29	1.90	1.50	-	-
0.42 mm	Single	Serviceability	3.72	2.64	1.73	1.33	0.94	0.55	0.39	0.23	-	-
	Single	Strength	7.18	5.42	4.17	3.53	2.89	2.25	1.88	1.50	-	-
	End	Serviceability	4.59	3.64	2.68	1.73	1.41	1.09	0.77	0.45	-	-
	End	Strength	6.23	5.04	4.10	3.17	2.81	2.46	2.10	1.75	-	-
	Internal	Serviceability	5.61	4.33	3.15	1.98	1.67	1.36	1.18	1.00	-	-
	Internal	Strength	7.15	5.58	4.58	3.58	3.19	2.79	2.40	2.00	-	-
0.48 mm	Single	Serviceability	-	3.55	2.73	1.91	1.09	0.95	0.80	0.65	0.51	0.36
	Single	Strength	-	6.61	5.79	4.98	4.17	3.58	3.00	2.42	1.83	1.25
	End	Serviceability	-	4.36	3.43	2.50	1.57	1.35	1.13	0.91	0.69	0.47
	End	Strength	-	5.21	4.57	3.93	3.29	2.97	2.64	2.32	1.99	1.67
	Internal	Serviceability	-	4.64	3.79	2.94	2.09	1.61	1.40	1.18	0.97	0.75
	Internal	Strength	-	5.92	5.21	4.50	3.79	3.08	2.77	2.46	2.15	1.83
The values are for use with steel supports with a minimum thickness of 0.75mm, G550.

Water Carrying Capacity

Maximum Roof Run For Drainage (m)
Roof Slope	Peak Rainfall Intensity (mm / hr)
Roof Slope	150	180	200	250	300	350	400	450
2°	188	157	141	113	94	80	70	62
3°	231	192	173	138	115	99	86	77
5°	298	249	224	179	149	128	112	99
7.5°	366	305	274	219	183	157	137	122
10°	424	353	318	254	212	181	159	141
15°	522	435	392	313	261	224	196	174
The peak rainfall intensities shown represent a 100 year average recurrence interval (ARI) for a five minute rainfall duration. If roof penetrations exist, the total roof run will generally be greater than the distance from ridge to eaves at the location the penetration interferes with the runoff. Contact Stratco if further advice is required.