Aluminium is one of the metal roof types that you can choose other than steel or zinc. Not all metal roofs are the same. The difference in material used will have different characteristics and hence brings a different level of performance. In this post we will breakdown the disadvantages of aluminium roofing sheets.
Roofing material suppliers would boast on this one main advantage of aluminium roofing sheet which is being corrosion-proof. That is great. But, there are other considerations of the material that we should know about as a consumer. This will provide a certain level of clarity to that and hopefully help to guide your decision.
Let’s dive in.
Disadvantages of aluminium roofing sheets:
1. Aluminium roofing sheets are much more expensive
Aluminium is considered to be a much higher quality material compared to zinc or steel. This sets it at a higher price in the metal roof market.
Due to its durability compared to roofing materials such as tiles or asphalt shingles, it is also much more expensive to install. The way it is being setup can be different and hence require well-trained roofers.
2. Aluminium roofing sheets can be noisy
One main issue with aluminium roofing sheets and other types of metal roofs is that they can be noisy when it rains. Each heavy droplet of rain is like the stroke of a drumstick to the batterhead of the drum.
During heavy storms, they form a chaotic symphony of drumming that can be annoying to some people. An extra sheet of sound-proof material could be installed right underneath the aluminium roofing sheet to reduce the noise.
3. Aluminium is easier to dent
The characteristics of aluminium is that it is malleable. Malleable means that it can be hammered into a shape without cracking or breaking. While this may sound like a good feature that the aluminium sheet has, it might not be so when it comes to protecting your house from the elements.
Any heavy things falling onto your aluminium roof such as a branch during a heavy storm could make its mark on the roof. The dent would affect the aesthetic appearance of the roof. Plus, that can also reduce the efficiency of the flow of water on the roof.
4. Aluminium roofing sheets expands more under the heat
This is slightly more related to science. So, bear with me!
Let’s say there are two types of metal roofing materials, steel and aluminium. Under the same temperature, the aluminium would expand about twice than that of steel. This is due to the metallic properties of the aluminium itself. Nothing much can be done to alter these properties.
This means that when the roof expands, there could be a risk of damage to the aluminium roof sheet or even tear around the nail hole that can lead to roof leaks. This sounds like a fearful disadvantage of aluminium roofing sheets.
However, worry not! Times have changed!
A professional and trained roofer would be able to set the roof foundation right and to lay the aluminium roofing sheet properly. Therefore, the expansion of the material under the sun will not be a problem. On the downside, this would translate to more cost on the roof installation.
5. Roof repair cost for aluminium roofing sheets can be higher
Aluminium roofing sheets are well, sheets of aluminium overlaid and arranged on each other. It is not like tile or asphalt shingles where one cracked or damaged shingle can be easily replaced with a new one. The same goes for other types of metal roofs. Different material may require different ways to fix the metal roof.
In the case of damage and requires replacement, the entire aluminium roofing sheet needs to be taken out and replaced with a new one. This is one of the common disadvantages of metal roofs. So, the roof repair cost may not be as cheap as those shingle types of roof.
6. Oil canning can happen
Image from metalconstructionsnews
Aluminium roofing sheets are prone to oil canning. That is the appearance of uneven surface on the roof. It may seem as if the roof is bulking in visible waviness that can change at different times of the day. This appearance can be a bit repulsive to homeowners.
Oil canning occurs due to unevenness of the milling process during the manufacture of the sheets. Other factors include improper handling of the aluminium roofing sheets during installation and also inadequate space between the sheets for thermal expansion.
This can be overcomed by using thicker roofing sheets, applying a low-gloss paint to reduce the reflectiveness as well as picking a skilled and experienced roofer to install your roof.
7. Poor fasteners installation could cause roof leak
Fastener is the screw that holds your roof onto the substrate or deck. Unfortunately, human error is one of the most common reasons for faulty fastener installation. These are potentially open spots on the roof that rainwater can seep in.
Some of the common human errors on fastener installation are:
Image from JLConline
Off-center fastener – The screw is driven into the roofing panel at an angle. Hence, the washer cannot sit flat and seal the hole effectively.
Under-driven fastener – This happens when the screw was not driven to close the gap completely. When water flows, it can easily pass by the washer fastener and leak into the roof. This often happens when the roof installer fears over-driven screws.
Over-driven fastener – This typically happens when the roof contractor screws the fastener tighter than it should in an attempt to make it as waterproof as possible. However, this can crack or damage the washer.
The best way to avoid the fastener problem is by choosing a qualified and reputable roof contractor to install the aluminium roofing sheets for you. This will help reduce the likeliness of any roof leak surfacing in the future.
It also will take a different approach when we talk about how to find metal roof leaks compared with other roofing materials. But for starters, you can check out the fasteners.
8. Prone to galvanic corrosion
Galvanic corrosion happens when roofs of different metal types interact with each other in the presence of electrolyte which in this case is rain water. This will cause the deterioration of the roof material to happen faster.
One metal type will rust faster than the other and hence compromise the roof integrity. This is another important factor to pick the right roof contractors to install the roofing system on your house. A skilled contractor would pick the same metal material from the roofing sheets to the fasteners.
There’s a lot more science to roofing than what meets the eye. Understanding metal properties such as thermal expansion and galvanic corrosion is just part of a roofer’s task. This knowledge is essential to help maintaining a metal roof correctly and to make sure your roof lasts as long as it is intended to.
Hope that this article on disadvantages of aluminium roofing sheets opened up your eyes into the roofing industry a little bit. It all goes right down to working with the right skilled roof contractor.