This is a complete guide to steel-framed buildings. In this article you will learn about:
- the concept of steel frame houses.
- answers to common queries.
- construction methods for steel framed buildings.
- the pros and cons of steel-framed buildings.
To learn why a house built using a steel frame is a highly efficient construction method while understanding the drawbacks, read on!
What is a steel frame house?
A steel framed house is classified as being of non-standard construction as opposed to other types of traditional house construction using wood frames. The steel frame structure is often not obvious, being hidden behind cladding, external brickwork or render.
Increasingly, more factories are making steel frames for the house-building industry using the `light gauge steel construction’ technique: lightweight steel is made from thin sheets of steel measuring between 1-3mm, which are cut and constructed using welding, bolting or riveting techniques, into the required shape at the factory.
On-site, the light steel is fitted to concrete foundations before other materials are used in the construction process to fill the structure of the house, such as brick, render and timber studs.
Improvements to steel manufacture
Historically, steel has been regarded as a cheap construction method, used, for instance, to build agricultural sheds. However, steel manufacture has undergone vast improvements: it is now considered a high-quality construction material with key attributes for modern buildings and steel framed houses could become a more popular choice.
The choice of any building material involves huge trade-offs, and it is difficult to optimise the design for any given situation because objectives such as cost, quality and aesthetics differ, points out Alan Muse, Head of Construction Standards at the Royal Institution of Chartered Surveyors. He said:
Constructing houses from steel is not a new concept: it was commonly used to build houses after World War II. For residential construction, steel offers longevity; if it is fire-protected it will last longer than wood frames, and it is watertight. A disadvantage is that it is not so good at stopping noise, for example between apartments in a building. However, steel is strong, therefore resistant to wind and earthquakes, it is adaptable and steel components can be made to any shape. It is particularly suited to the current trend for large spans in houses, as steel can span more quickly than cellular construction. It also encourages off-site fabrication which helps maintain high standards of construction.
Mr. Muse added that years ago steel corroded as it was not well protected, making it more difficult to obtain a mortgage for a steel framed house, whereas modern steel is high quality. Most steel production has a high embodied carbon content, which is a problem given the current focus on sustainability, but innovations are taking place to make low-carbon steel components.
These include the use of hot zinc coating, extra powder treatments, and improved joining methods while light steel and mild steel are also being increasingly used in steel framed buildings.
While timber-frame construction is more sustainable than steel framed buildings, it is more susceptible to fire damage; this is one example of the trade-off decisions that must be taken according to the location of a building, and different solutions may need to be implemented to achieve all the aims of a scheme. However, if a steel-framed house is well-designed and well-built, in many cases it can satisfy requirements.
Can I get a mortgage on a steel-framed home?
Problems with resale and insurance mean lenders view steel-framed homes with caution due to their record of variable build quality. While steel framed houses are often bought by cash buyers, it is possible to get a mortgage for a steel frame house. However, the range of lenders is limited due to a history of defective steel frame houses. Most lenders are restrictive over the specific type of steel structure they will grant mortgages on.
A mortgage broker may be able to help with a search for the right lender for a steel frame house. Mortgage lenders define steel frame houses as category A, B, or C. Category A means that a house is mortgageable in its original condition; category B means that a property is mortgageable following approved repairs, and category C applies to houses that are defective, and therefore not mortgageable.
How easy is it to insure steel frame houses?
It is important to be aware that uncertainty surrounding the reliability of steel frames creates difficulties in obtaining insurance for many buyers, leading to the potential for higher premiums for steel framed houses.
How can I identify a steel frame in a property?
While steel-framed buildings can be difficult to spot for a layperson, a steel frame may be evident in the loft space and roof structure. It is also possible to see parts of a steel frame at meter entry points into a property, at the back of cupboards, or at areas of corrosion. Other tell-tale signs of a steel structure include patterned cracking on the skin of external brickwork and crooked internal door and window openings.
At auction, a buyer should be sure of whether or not the house they are bidding on has been built using a steel frame, especially if an agreed mortgage depends on it.
Advantages of steel frame construction:
- Steel framing is cheaper than wood frame construction methods.
- The vast majority of steel is recyclable.
- Modern steel-framed houses have great structural integrity; they are high-strength, durable and ideal for high-rise building construction.
- Steel framing is fire-resistant and does not warp or expand.
- It is faster to assemble a steel frame on a construction site than a timber frame.
- A steel structure offers customisable options to suit an architect’s design; it can be used with brick, cement, wood and can also be painted.
- Being weather resistant, steel handles weather conditions well; it sustains less water damage than wood and does not rot.
- A steel frame home is highly resistant to fungus.
- As steel-framed panels are grounded to earth, they work well as lightning rods for dissipating lightning bolts into the ground, making structures resistant to natural disasters.
- Light steel framed building parts can be ready-made off-site quickly via the modern method of construction process.
- Structural steel has great design flexibility which may be attractive to self-builders.
- In recent years the steel industry has developed its offer due to the benefits of off-site residential construction: lightweight steel can include light steel window and door frames.
- New steel framed houses are high quality products that can offer high levels of energy efficiency.
Disadvantages of steel frame construction:
- Difficulties in obtaining a mortgage and building insurance.
- A building survey is recommended before purchase rather than a HomeBuyers Report; this costs more but steel-framed houses are classed as being of non-standard construction. A building survey is a non-intrusive inspection and might not reveal structural problems if they are hidden behind the construction. A steel framework is difficult to identify without opening up the property walls. A surveyor may recommend that a more intrusive survey such as a full structural survey be carried out.
- Steel elements can corrode badly and develop structural issues, especially at the base of stanchions, galvanised steel windows, and joining points, however, modern steel has enhanced rust resistance.
- Poor insulating properties and energy efficiency; steel is a conductive material, conducting heat 300-400 times more quickly than wood, reducing the insulation properties of wall insulation by 60%. This is due to thermal bridging: heat takes the most conductive path to dissipate. Thermal bridging can also cause black stains on cold areas of walls.
- Steel framed houses can lead to higher heating bills to counter the poor insulation.
- A steel-framed construction makes it difficult to spot problems like subsidence and rising damp.
- On purchase, a larger deposit may be required, and potentially a higher interest rate will be charged on a mortgage for a steel frame home.
- Large amounts of energy are needed to manufacture steel, involving the burning of fossil fuels.
Final thoughts on steel framed houses
Today, high quality products are being made for the structural steel industry. Light steel is durable and thanks to its impressive strength to weight ratio, it can enable strong buildings to be created that use minimal materials, reducing costs. As well as enabling the construction of lighter buildings, light gauge steel frames are also easier to transport and install than traditional frames.
The fact that steel is high strength, adaptable and can be quickly constructed are also major points favouring its use. The advancements being made could well make steel framed houses a more popular choice for UK house builders.
Do you have a view on steel framed houses?
Let us know what you think. If you have experience of either buying or living in a property with a steel frame construction, we would be interested to hear your comments.
By Tom Fenton 
By Annie Button 
