Steel Frame Construction

Lightweight steel is generally used as a secondary structure between the floor and columns of a primary structure to support the internal and external finishes.

There are 3 categories for walls using lightweight steel, and these are: infill walls, continuous walls and panelised systems.

SFS Infill systems are one of the most commonly seen steel frame solutions. Infill walls are generally constructed from pre-galvanised coated steel from zinc coated steel sheets, and usually take the form of U or C-shaped tracks.

These U-shaped tracks are fixed to the base and head of the primary structure with the C-shaped studs installed in between to create a frame.

Continuous walling (also known as oversail walling) is fixed externally to the primary structure and uses components very similar to that of the infill wall system.

With continuous walling there is more design input required for the connections and the longer length vertical studs, as they can continue over several storeys.

The panelised wall system is a pre-formed non-loadbearing steel frame infill solution, manufactured and factory assembled to the project requirements. These are manufactured in different sizes and allow for a quicker installation process.

Steel frame construction is highly versatile when dealing with thermal performance as the actual depth of the studs allow for as much or, as little insulation as is required.

Foam or mineral / glass wool-based insulations are fine for use, but the wall build up should be reviewed for the requirement of a vapour control layer or a vapour check plasterboard.

It is always recommended that condensation calculations are carried out alongside that of the U-Value calculations to ensure that the build-up is technically correct.

Steel has a very intensive production process which can leave a large carbon footprint.

The requirement of the coal derivative ‘coke’ to help the manufacturing process is seen as a negative process, but is required as a fuel, as it can create intense heat with little smoke.

Despite this, steel is highly durable and 100% recyclable and therefore it can be used again and again.

Warm frame construction is when the insulation is installed on the outside of the steel frame only, leaving the gap within the frame uninsulated.

Cold frame construction is the opposite, whereby the all the insulation is maintained with the depth of the frame and no insulation is installed outside of the sheathing board.

Hybrid frame construction means that the insulation is installed both within the depth of the frame, as well as the outside of the frame.

With this type of construction, as with cold frame, there may well be a requirement for an internal vapour control layer.

The choice for finishes with steel frame construction is vast – including masonry, cladding and glazing.

Whichever finish is chosen, it is recommended that a full technical design is sought as different finishes will require different carrier systems, as well as having a bearing on the external loading.

New build warranty companies require a drained cavity whenever a steel or timber frame construction is used for residential purposes.

According to the NHBC Chapter 6.10.16 (Light steel framed walls and floors) the cavity requirements for masonry is 50mm, for render onto a board background it is 25mm and for other types of cladding a 15mm cavity is required.