A Comprehensive Comparison of Timber and Rolled Steel Sheds
When considering adding a shed to your property, durability and longevity are key factors to evaluate, especially when you are building on your forever property or passing the property to future generations. Sheds come in various materials, but two of the most popular are timber and rolled steel. In this blog, we'll explore the expected lifespan of each type of shed, and why one lasts significantly longer than the other.
Timber Sheds
Timber sheds are known for their robust durability. Most timber sheds in New Zealand are constructed primarily from treated pine, and these sheds can last significantly longer than their rolled steel counterparts.
Lifespan of Timber Sheds
Timber sheds can last anywhere from 30 to 50 years and even longer. High-quality, treated timber sheds, such as those made from pressure-treated pine, can provide exceptional longevity. These days, the timber is treated with chemical preservatives in a highly pressurised environment, meaning the chemicals penetrate deep into the timber. This significantly reduces the effects of decay, meaning the timber will be structurally sound for decades.
Building Consent and Warranty
Timber pole sheds typically come with a remarkable 50-year building consent. This is the longest building consent you can get, and the extended period is a testament to their durability. It is important to note that the warranties on each of the individual building materials will vary, however the building consent length means that the council takes into account the design and location of the building and they expect the building to be structurally sound for a minimum of 50 years.
Rolled Steel Sheds
Rolled steel sheds are constructed from portals that are formed by pressing approximately 2mm thick tin into a shape. These types of structures rely on the shape of the portal, rather than the thickness of the steel for their strength. The rust protection coating on this steel is very thin and is usually only a light galvanise coating on the main coil. Hot dip galvanizing is widely considered the best rust protection method however this is not an option for rolled steel. This is because the 2mm thick tin is too thin to withstand the heat of the galvanising baths and will warp or even melt the portal.
Find out more about the best rust protection in this blog.
Lifespan of Rolled Steel Sheds
Rolled steel sheds typically last between 15-30 years depending on the environment in which it is built. This is because the steel is so thin and because this system is particularly susceptible to rust due to the limited rust protection options. Another point to note is that most rolled steel systems rely on thousands of tec screws to hold the structure together. When a screw is put through the 2mm thick rolled steel, it heats the steel up and strips away the rust protection, meaning that all structural connections are held by raw, unprotected 2mm thick tin. This makes the rolled steel system highly susceptible to rust which can quickly compromise the structural integrity of the building.
Building Consent and Warranty
Most rolled steel sheds come with a 25-year building consent. This shorter period compared to timber sheds reflects the different wear and tear characteristics of rolled steel, especially when rust sets in as outlined above.
Another point to note is that this system can be easily damaged if a portal is knocked. Rolled steel sheds rely on the shape of the portal for strength, rather than the thickness of the steel. For example, if you back a vehicle into a structural portal, you will very easily dent the 2mm thick tin, therefore altering its shape. This means that the strength of the portal is compromised and can lead to structural flaws which are very costly to repair, if the damage is repairable.
Cost
While costs vary widely between systems, designs and companies, rolled steel is often cheaper than timber when comparing a kitset costing. The difference in the kitset costs can be between 10-20% however that gap is typically narrowed when comparing the full build costs. This is because most timber pole sheds are faster to construct, but more importantly, they have much simpler foundation requirements. Steel sheds require a structural floor with an engineer's sign off as the shed relies on the slab for strength. This means that perimeter thickenings and complex reinforcing designs are required. In comparison, pole sheds don't rely on the slab for strength, therefore they are nonstructural and are classed as an accessory. This means perimeter thickenings are not usually required as the timber poles are simply concreted into a hole in the ground.
In Conclusion
When choosing between timber and rolled steel sheds, it's essential to consider not just the initial cost but also the long-term value and lifespan of your shed. If you are building your shed on a property that you will be selling in 5 years, rolled steel may be a better option. If you are building on your forever property, or if your property is going to be passed onto future generations, consider a timber shed. A timber shed may cost a few thousand dollars more in the beginning, however they will last at least twice as long, giving you a building that will provide long term return on investment and much lower cost of ownership.
The Alpine system is no different, it utilises timber poles and framing, and then a hot dip galvanised structural steel rafter is used to make the building clearspan. This steel is typically 8-10mm thick and all the connections are bolted together. This makes the building extremely strong and is also backed up with a 50-year building consent.
If you are building with the future in mind, talk to the team at Alpine, they would be happy to help you get a solution that will be fit for purpose both now and for decades to come.
