Materials
Stramit Purlins and Girts are manufactured from hi-tensile steel, with a minimum Z350 galvanised coating (350g/m2) conforming to AS1397. Other coatings, grades and materials may be available, subject to inquiry.
The mass and steel grade for each standard Stramit® Purlin and Girt section are shown below:
Section
C or Z
Thickness
mm
Strength
MPa
Mass
kg/m
100-10
1.0
G550
1.77
100-12
1.2
G500
2.11
100-15
1.5
G450
2.61
100-19
1.9
G450
3.29
150-10
1.0
G550
2.43
150-12
1.2
G500
3.90
150-15
1.5
G450
3.59
150-19
1.9
G450
4.51
150-24
2.4
G450
5.67
200-15
1.5
G450
4.50
200-19
1.9
G450
5.74
200-24
2.4
G450
7.21
250-19
1.9
G450
6.50
250-24
2.4
G450
8.17
300-24
2.4
G450
10.18
300-30
3.0
G450
12.69
350-30
3.0
G450
15.19
Adverse Conditions
Stramit® Purlins and Girts will give excellent durability in most applications. In exposed, unwashed areas subject to salt-laden air or other corrosive matter may need additional protection. Stramit® Purlins and Girts are not recommended for use within 450mm of most soil.
Compatibility
Contact between galvanised steel and copper (e.g. pipework) must be avoided as premature corrosion will occur.
Standard Sizes
Stramit offers a full size range from 100mm to 350mm in web size increments of 50mm. This ensures economical design by using adequate section size in the desired thickness. All sizes are available pre-punched and come complete with a full range of accessories including bridging and brackets.
Expansion Joints
Roof sheeting is generally limited to the lengths shown in the table below to avoid problems associated with thermal expansion. Roof runs longer than these generally incorporate an expansion joint. This is acheived by reducing the plane of the purlins sufficiently for each sheet run to overlap the next.
Through Fixed
Concealed Fixed
Light
25
65
Dark
17
25
Sizes
The table below lists the standard sizes and thicknesses readily available.
C Sections
C Sections are mono-symmetric sections. Their freestanding, stable shape allows easy handling and storage and is adaptable to 'I' and 'box' configurations.
Sections
Web D
mm
Flange
B
mm
Lip
L
mm
Thickness
t
mm
XC
mm
XS
mm
C100-10
C100-12
C100-15
C100-19
102
102
102
102
51
51
51
51
12.5
13.0
14.0
15.0
1.0
1.2
1.5
1.9
16.1
16.2
16.3
16.4
25.8
26.0
26.2
26.5
C150-10
C150-12
C150-15
C150-19
C150-24
152
152
152
152
152
64
64
64
64
64
14.5
15.0
16.0
17.0
18.5
1.0
1.2
1.5
1.9
2.4
18.4
18.5
18.6
18.7
18.9
30.1
30.3
30.5
30.8
31.1
C200-15
C200-19
C200-24
203
203
203
76
76
76
16.0
19.5
21.0
1.5
1.9
2.4
20.1
20.9
21.1
33.6
34.9
35.2
C250-19
C250-24
254
254
76
76
19.0
20.5
1.9
2.4
18.3
18.4
32.2
32.5
C300-24
C300-30
300
300
96
96
28.0
31.5
2.4
3.0
25.0
25.8
42.7
44.0
C350-30
350
125
30.0
3.0
33.3
55.0
Z Sections Z Sections are asymmetric sections. The uneven flange widths allow the sections to be lapped to permit structural continuity, a factor that contributes significantly to building economies. Savings achieved by lapping Z sections, resulting from the increase in strength and rigidity, more than compensate for the extra purlin material required in the lap itself.
Photographs
