Flat Pack Shed Construction & Design Weakness

There are a few different construction methods used by different manufactures. A couple of common ones are a metal tag/clip system, and tek screws. The first is a very fast method of construction – you can get most of the joints assembled with a quick tap with a wooden mallet. There are then often some metal cross bracings used that utilise a few tek screws to hold it all together.  There is often very little actual framing used, as the shed relies on the panels themselves to not only provide the cladding, but also be the framing as well as providing sufficient stiffness to the structure.

The other method relies on a solid frame structure (normally steel) which then has the panels attached. The cost of this sort of design is significantly higher, but then so is the strength of the resulting structure.

There are a couple of standards that the shed is constructed to, based on the actual location (Vic, NSW, Queensland etc) and the likelihood of severe storms.  The standard for Victoria doesn’t require a cyclone rating, and despite the extra cost, there is surprisingly little that is added to the shed design to get the extra rating.

From experience however, the larger sheds are really tested even in Victoria with the wind strength and speeds that are experienced with today’s weather patterns.  Despite manufacturer claims, some extra bracing is not just a good idea, but I’d suggest mandatory given the weakness of some designs. The clip-together designs have an inherent weakness that if a panel is torn off by the wind, the whole shed’s integrity is compromised, and likely to also succumb.

The point of greatest weakness is the upper corner of the door(s), with the wind gusting over the roof attempting to lift it, it is these corners that often will start detaching themselves first.  Knowing this however means we know where to add some extra reinforcing, which can be as simple as some extra strapping. The other issue can be the tek screws themselves when they are relied on to hold the whole unit together. Some of the sheds use a very thin steel that doesn’t provide enough material for the screw to bite into, and the forces (particularly the vibrations from wind gusts) can cause the screws to loosen, or pull out altogether. Adding some rivets in strategic positions can greatly add to the overall strength of the shed.

I’ve found that even a weak shed can be given a significant boost by adding a wooden subframe.  This has a number of benefits – in addition to the significant overall shed strength, it provides a good structure for adding storage, and can be skinned on the inside with particle board, which then provides a perfect space to be filled with insulation (if desired / warranted).

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