Melbourne’s Experts in Custom Built Farm Sheds

Fair Dinkum Sheds range of custom built farm sheds come in a number of styles. Open bays, closed bays, roller doors, different heights, spans and lengths to suit whatever you need. Generally with a farm shed the aim is to get the most square meters for your money while not compromising in structural integrity and material quality. Often a floor is not required in a farm shed and a rock base is sufficient. An infill slab is never recommended for a shed and will most times void your Colorbond warranty. When a shed is built on a slab, sometimes the daylight gap in the sheeting profile (ribs) where the cladding meets the slab is a concern and flashing the void is a much better method than pouring concrete against the wall and will maintains the warranties if installed correctly. If building on pad foundations only, it is wise to complete the site cut and installing any rock prior to building the shed, it is easier for the machine operator, easier for the erectors and a better finish overall. The building code states metal cladding should be 70mm or more from ground level on a finished building.  When building on Pad footing only the columns would be supplied 400mm longer than the building actual height so the footing can be kept lower than the wall cladding, usually at ground level with a slight camber to prevent water ponding in the footing. The longer column also can help allow for any site fall if the site cut has not been completed. The installer will cut the columns to suit the required finished floor level.

Reputable steel suppliers will use the code BMT to describe the material thickness. This stands for Base Metal Thickness. It’s the industry standard, if you see TCT (Total coated thickness) next to a material description it is safe to assume the steel is imported and relying on the coating thickness to make it sound thicker or stronger. Structural capability of metal cladding is a function of the base metal thickness and steel grade whereas corrosion performance is provided by the metallic coating thickness and type. BMT is the relevant measure for structural strength.

Insist on Base Metal Thickness to ensure an even playing field
As an example –

If a design specifies 0.42 BMT steel, supply of imported 0.42 TCT steel would deliver inferior performance as 0.42 TCT is only 0.37 BMT. This table below shows the difference in steel thickness described as TCT rather than BMT

AM125 to AS1397:2011 Zincalume steel supplied BMT AZ150 imported Zink-Aluminium coated steel supplied as TCT
0.35 BMT – k-panel suitable for wall cladding 0.35 TCT = 0.30 BMT. 16% thinner
0.42 BMT – corrugated, monoclad suitable for wall and roof cladding 0.42 TCT = 0.37 BMT. 12% thinner
0.48 BMT – corrugated, monoclad suitable for wall and roof cladding 0.48 TCT = 0.43 BMT. 10 % thinner

Ensuring your shed is ShedSafe accredited ensures your cladding will be quoted in BMT and also be Australian steel meeting the relevant Australian standards.