Advanced Structural Designs

ACN 097 789 87 92 Vasey Cres CAMPBELL ACT 2612

Telephone 61612171 Facsimile 61612170

Email mal@structuraldesigns.com.au

When does it make sense to use steel framing in residential Construction?

Steel framing did have a poor reputation for a while when it was carried out using heavier members and poor quality welding. One of the main concerns was that it occasionally broke welds under thermal loading and was difficult for other trades to screw into. These days the joining is with high pressure crimping tools and the wall thickness is down from 1.2mm to 0.55mm which makes fixing Gyprock, cupboards etc far easier.

You would normally expect to spend less on the materials for framing a steel house but the final product will generally be a little more expensive. If you compare the prefabricated components we have found walls are around 10 to 15% more expensive but trusses cost about the same for a very simple roof. For trusses you are generally saving money if the span is over 9.5 metres. If you do use steel framing and aluminium windows you can often avoid the need to termite proof the building. Under these circumstance the overall costs can be much closer.

We often recommend this form of construction for owner builders as it will weather well if the building process is to take a year or two.

Some of the benefits of steel framework include

Termite proof framing.

Light Weight (around 40%).

True alignment (no bows warps or twists).

No moisture movement.

Durability.

Pre-punched holes allow easy plumbing and electrical rough in.

Tile and brick ties clip into place.

More safely deals with stray currents and lightening strikes when correctly earthed.

Some of the tradeoffs are

Less trade familiarity.

Greater cost (around 10 – 15% for prefab walls though roof trusses are often competitive).

Less flexibility where site changes are required.

More thermal movement.

Cold bridging (see note below).

Need to batten out floor if strip flooring and hidden fasteners required

In most areas of Australia it is possible to have roof trusses at 600 centres and fix the Gyprock straight to the bottom chord. This practice is not recommended in the ACT as experience has shown that after a few years the truss chord location can be seen through the paintwork. This is believed to be the result of thermal bridging during our cold winters condensing water onto the plasterboard. Battened ceilings do not have this problem when you use radiata battens.

If your house is relatively regular in design and has a trussed roof you can generally take your plans straight to a fabricator like Touchsteel or Freedom Homes if you are in the Canberra region.

If you have walls over 3.0 metres raked ceilings etc it is often preferable to have framing plans drawn by structural consultant before you shop the wall framing and trusses around. If you need advice from a Structural Engineer in Canberra ACT and surrounding districts on the best option for your structure call Mal Wilson from Advanced Structural Designs on 02 61612171.

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