Steel comes in assorted widths and thickness, this all has a major effect on build quality, weight and cost of wrought style metal product. The heavier it is the more it costs. Listed below is common sizes and what i consider them useful for.

Hollow section

Hollow section steel such as square / rectangular box and round tube is more expensive by weight than solid. Because of the additional cost of turning it into tube form. Large hollow section is ideal for gate posts. Smaller hollow section can be used for gate frames giving a rigid frame without the cost and weight of solid. hollow can also be used for upright bars on gates and railings. But isn’t really cost effective until 20mm. One thing to note about hollow is “wall” thickness. Very rarely mentioned on any specifications for wrought iron work. But certainly very important when price comparing.

Wall thickness

Most hollow section is available with wall thickness options. 50mm square perhaps has the most options.

it is available in 2.5mm thick wall, this is quite thin but makes good for being light weight. This would be fine for perhaps a garden gate frame, or short connecting posts for railings. Certainly not for connecting posts on patio railings as its to flexible.

3mm thick is another option, increased wall thickness makes it more rigid. but more expensive than 2.5mm. Increase rigidity makes it more suited to longer posts, larger gate frames

4mm thick wall starts to get heavier and obviously more expensive, but increase strength makes it a good candidate for for the frame of a large set of estate style gates and good for connecting posts on patio railings.

Square hollow section sizes available

20mm Square available in 2mm and 2.5mm thick wall. – Useful for – uprights in gates or railings

25mm square available in 2mm, 2,5mm and 3mm thick wall – Useful for – uprights in gates or railings

30mm

40mm

50mm

60mm

70mm

80mm

90mm

100mm

120mm

150mm

200mm

Square solid or Round solid

6mm square / round

8mm square

10mm square

12mm square

16mm square

20mm square

25mm square

30mm square

Flat

10mm x 3mm = Use light weigh scroll material

13mm x 3mm

13mm x 5mm

13mm x 6mm

16mm x 3mm

16mm x 5mm

16mm x 6mm

20mm x 3mm

20mm x 5mm

20mm x 6mm

20mm x 8mm

20mm x 10mm

25mm x 3mm

25mm x 5mm

25mm x 6mm

25mm x 8mm

25mm x 10mm

25mm x 12mm

30mm x 3mm

30mm x 5mm

30mm x 6mm

30mm x 8mm

30mm x 10mm

30mm x 12mm

40

Rounds and Square