Why are we steel talking about this crap?
If for some reason you have been living under a rock, it will be news to you that there has been a huge spike in the supply and demand of timber. It has become so hard to get your hands on, that we have been told there is a minimum wait of 5 months for certain timber products! This leaves the building industry in a bit of a sticky situation where projects are being put on hold or severely delayed due to a lack of timber.
Along with a timber shortage, it has also been well-reported that there are shipping delays worldwide. Supply chains are struggling to move things around the world due to global demand for every product. In building, there are certain materials and hardware delays impacting delivery and pricing. Hard border closures and a tight cap on manufacturing/building has lead to labour shortages and added another element to this complex spider web. We understand each industry has its issues at the moment, but this is ours.
Like anything, when there is little supply and large demand, prices go up. Across the board, core logic is reporting that general construction costs are up 3.9% in Victoria within the last year. In residential construction, we are finding that prices are up between 8-10% depending on the project. For example, in January 2021 we were paying $2.95l/m for 90x45 timber (the most commonly used timber in a home). By May 2021, this increased to $3.25l/m. Currently, as of the 1st of September, we are now being charged $5.30l/m. That's a 79.67% increase and it's projected to continue rising. Not too long ago we were able to call up a few days before we needed our timber and we would receive it within the week, at the latest. Now it's a minimum 12-week wait, and that's if you're lucky.
As a result of this, many builders have had to absorb the increased cost due to our fixed priced contracts. Combine this with the delays and it starts to really impact us as business owners. We're definitely not saying that our industry has been hurt the most and acknowledge that we've been quite fortunate to continue working when so many others haven't had that opportunity. a lot of people are doing it quite hard, some losing jobs or not being able to work. However, it is still a big challenge that our industry has had to face and has seen many builders try to cover themselves by ditching timber for steel frames - a reactive decision that is going to cause themselves and the homeowners many issues down the track.
I have talked about this in the past, but if you're reading this and are considering building with steel frames, or being pressured into building with steel by your builder/designer...
AVOID IT AT ALL COSTS
Don't entertain the idea and don't be fooled by it. Just because it's "apparently" more readily available and potentially cost-effective, doesn't mean it's a great product. We believe that you should not be panicking, and if that means delaying your build until the prices drop or timber is more readily available, you should wait it out.
Now, we can't just say all this without backing it up with some information. We know that this may cause an argument between you and your builder, however, they should be providing you with the correct advice, not one that works in their schedule and helps their bottom line. I feel like builders and designers have a duty of care to explain the consequences of using a steel frame, rather than selling it just because it suits them.
Let's start with what you're going to be told about steel frames, not taking into account the price or current availability.
“They Are Fire Resistant” - I don't intend on having my builds catch fire, but most, if not all of the fire protection occurs from the outside. If the fire does reach your frame, it's most likely game over anyway. The intense heat that will occur will either burn your timber to ash or cause your steel frame to buckle as the strength of steel decreases when exposed to high temperatures, meaning both are useless if you need to rebuild. It's not as if a fire will rip through the home and the only thing still standing is your steel frame!!!
“They Are Sustainable” - this is just a load of crap and pure greenwashing. Steel is one of the biggest contributors to CO2 emissions - a quick google will tell you this. You can read our other blog here that speaks to this in far greater detail.
“They Are Termite Proof” - yes they are, but even with a steel frame, you will still have to protect it against termites as per the manufacturer's suggestion. Termites are not picky eaters and can work around the frame until they find some timber to consume. If you're worried about the dangerous chemical being around the home, there are now products that are far less harmful but still do an excellent job.
They Are Stronger and Straighter - yes this is correct. Steel won't warp or swell but it does expand and contract depending on the temperature. This means you might hear crackling and popping in your structure at certain times! Steel framing companies deny this however it's very common to hear people living in steel-framed homes complaining about this. Currently, there is no study to confirm or deny this but I wouldn't be willing to test it out.
They Have a 50-year Structural Warranty* - Like all good sales pitches, this one has an asterisk next to it, one that is so clear it's almost impossible to find on the Blue Scope Steel website! Make sure you understand what is involved to obtain the warranty as these companies usually promise you the world but the fine print says otherwise.
At a glance, steel does sound great. When we think of steel, we think of something being robust. That's why we use it for structural beams to take the excessive load. But in residential construction that's where it should stop. So why should we avoid getting caught in this trap and rushing into a decision to use steel frames when it's highly likely to create problems in your home down the track? Let's dive into a few areas that you need to be made aware of before making a decision.
Performance and Ability to Fully Insulate
Have you ever seen a cross-section of a steel stud? They are U shaped with little returns that provide them with strength. When we fit insulation in a timber frame, the insulation is hopefully snug up against the timber stud and not compressed. So let's now add in steel studs. Due to the U shape, when the insulation is installed, it is only installed into the return of the U section, leaving roughly a 45mm gap where the "inside" of the stud is.
Plan view of a steel stud wall with insulation (top) and a timber stud wall with insulation (bottom)
This means a fair bit of insulation is missing in each stud. But how much?
If each stud is 2.7m high (average ceiling height in a home), and roughly 45mm wide this means a total loss of insulation of 0.125m2 per stud. It doesn't sound like much, but when you have more than 100 external studs on a standard renovation this adds up. In this case, it would equate to a total loss of 12.15sqm of insulation for every 100 studs. That's like leaving your external bedroom wall uninsulated. But that's just the beginning of this mess.
Having holes in your insulation has a huge effect on its performance. By just having 5% of holes in the external structure, the value of your insulation falls by 50%. On a standard 90mm wall you would most likely be putting in R2.7 batts (we hope). To make this now comply, you would need at least R5.0 inside your walls. If for some reason your builder or designer disagrees with this, it can be found in the National Construction Code (NCC) Table 3.12.1.1b.
Not only do you have a huge insulation loss, but you're now also inviting areas to be more prone to air leakage through the structure. This can lead to cold spots where your steel frame will act exactly like that can of coke you take out of the fridge which starts to condensate. Except that can of coke is your metal stud, and all that condensation will drip down the metal potentially causing corrosion on your steel frame. I bet this is one of the asterisk items in your 50-year warranty.
Thermal Bridging and Cold Spots
Metal is a greater conductor of heat than timber. It's just like your steel pot at home. If you leave a metal and a timber spoon in the pot, you're always more conscious of touching the metal spoon as it's likely to be too hot. That's because timber has 4 times the thermal resistance when compared to steel. The same thing happens in a metal frame where heat moves through the stud and warms up the interior surface, dramatically affecting the R-value of a wall. Studies have shown that this will relate to a decrease in your R-Value of 21.68% to 94.37%.
But let's be clear, all structural framing meterial will diminish the effectiveness of a thermal barrier, just some more than others. But how much worse is steel than timber? Let's assume we are installing an R2.7 Insulation batt in the wall cavity (90mm frame). This is known as the rated R-Value. But what is the effective R-value - how the wall material build-up and thermal bridging affect the rated R-Value
If we compare a standard wall, 90x45 studs at 450mm centres you will find that a timber wall will lose roughly 17% of the R-Value meaning the effective insulation is roughly R2.28 (reduction of R.405).
Timber stud wall Rated vs Effective R Value
Now let's change that wall to a metal stud wall with R2.7 insulation. This wall will lose roughly 63% of the R-Value. This means your wall is now only rated R0.99 (reduction of R1.701). Just this vast difference in effective R Value ratings should make you want to steer clear of a steel frame.
Metal stud wall Rated vs Effective R Value
This is something the steel frame manufactures know, and they have developed thermal break strips which do help combat this issue. However, if you read the fine print from the supplier it states that this strip must not be compressed, just like all insulation as it loses its ability to function correctly. This becomes difficult when you're trying to fix the cladding to the structure as the nail or screw will pull that cladding hard to your frame compressing that thermal break. Even if you get this right, how are we dealing with thermal bridging on the roof and floor?
Some people have gone full hog on the steel frame. Stumps, to the subfloor to frame to the roof. But what thermal bridging is happening with the stumps, subfloor and roof? The stumps are going to transfer that cold ground energy up to your subfloor, where most people are trying to use that crappy Aircell/aluminium foil insulation. That just means more metal to metal to allow a beautiful highway for heat to move along. This will eventually hit the bottom plate and move up the frame. The same can be said for the roof, however, this is a lot worse. On a nice sunny day, your roof will absorb that summer sun, move the heat directly through your steel trusses and migrate down to the frame.
This is becoming such an issue in construction that it's being addressed in the new version of the NCC due for release next year.
Corrosion
This one is a little more up for debate. Steel frame companies claim that their product is corrosion-free as all studs are coated in protective zinc just like your metal roof. However, these frames are usually cut or altered on site. This means that protective zinc is now exposed and at a much higher chance of corrosion. I do agree that without water, these frames won't rust. It's not like we are pouring water into the frame once the plaster is installed. Or are we...?
Since condensation is occurring on the metal frame, as this is the dew point, all this water is collecting on the inside. Not only that, the average house in Australia has air leakage of around 15ACH per hour. So with air movement, comes vapour. And with vapour comes moisture, which gets stuck in the frame. This can happen with all types of construction methods, including timber but while a timber frame could rot, a steel frame could corrode.
FOMO
Everyone wants something now. We are impatient. We want to keep up with the Jones' and flex our muscles. We don't want to be that person who isn't improving our home or making it look good. We are surrounded by it. Those pretty images on Instagram don't show you what happens behind the frame and what it took to get to that image. TV show's like The Block set unrealistic expectations. It's nothing like reality on a building site and it's just product after product placement (poor ones at that) being thrown in your face. But it's these shows that give people the urge to renovate or build and fast. We don't want to miss out because our friend is building and we want to do it too. So slow down for a minute, take your time, plan your project properly and chose the correct materials. If that means waiting an extra year or two, that's fine. It just means you will have more time to hopefully see a decline in the overall construction costs but giving you more time to get some extra pennies in the bank to get that kitchen you have seen on Instagram...
So when would we use steel frames?
We would only use them if we could fully continuously insulate the home (floor/roof/walls) on the outside of the structure. The only way to have a steel frame be thermally bridge free is to install a very thick foam or wood fibre product around the whole house externally. A thermal bridging analysis will need to be done to determine the level of thickness required to prevent this. If you can do this successfully, yes a steel frame will work. However, by the time needed to install huge insulation panels around the outside of your home, it would have been way cheaper just to use timber, even at this inflated price!
So be patient and if that means waiting 12 weeks for your timber frame, that's ok. As builders we know we are faced with this issue so we can order our timber well in advance and try to negate this as much as possible. You can even chat to your builder and have timber costs as a provisional sum. This may give more confidence to your builder to continue using timber as they don't have to account for more price increases placing large contingencies on this.
Yes, timber may go up in price, but it could also drop! It's just about being honest and open with your builder and discussing this.
Don't rush and feel pressured by your builder or designer because they told you steel is fine. At the end of the day, in 10 years when that frame is having issues, I bet you wish you waited or paid the current costs for timber. By being aware of this and doing some planning you can avoid this steel trap and build with a timber frame. No one has a crystal ball with this problem however lumbar prices are already dropping in the USA which may be an indicator of what's going to happen here.
Prevention is better than cure, and in this case, it's going to be one big expensive exercise for you to replace as the builder and architect will make sure that this doesn't fall on them! If you're confused or want to reach out to start planning your build, please don't hesitate to contact us for a chat. We love talking about all things building science!