Storage Shed Construction

After looking at prices and reviews for off-the shelf storage sheds I decided I would build one from scratch to replace one my Dad built about 15 years ago

Old shed
The existing shed – storm Eunice tore off the tarp that was covering the roof.

The design is purely for storage but it also needs to be reasonably secure as it will be sited in a remote location.

  • Overall size: 2.4m wide by 4.8m long.
  • Flat roof for ease of construction
  • Garage size & style doors to allow plenty of light when open and ease of access for large objects
  • Optional roof light panel
  • No concrete or bricks to be used.
  • Be able to withstand weather for at least 10 years without maintainance

I decided to use fence post spikes and fence posts for the main corners. The fence post spikes will go easily into the earth and the 100mm square fence posts will provide a heavy duty frame. All outward facing timber to be tanellised (weather-treated). The entire building will be raised from the ground to help prevent damp and rot.

I will then create a frame for the floor and another frame for the roof using strong C24 timber.

A double door will be created from the wood being used for the walls

For the roof I plan to use box section metal sheet, along with a single clear roof panel made of fibreglass.


Frames are constructed from treated 45mmx145mm C24 graded timber. These come in 4800mm lengths so I decided to use this as the overall length of the shed. They can be cut in half to provide a width of 2.4 metres.

To provide a solid floor I’ve set 4 intermediate joists, and for the roof frame 2 intermediate joists (as it does not need to be as strong). Floor span calculator

Because the roof frame will be on a slope, the floor frame needs to be slightly narrower than the roof one. With a 12 degree slope, I calculated the floor frame should be 2350 wide.

The walls will be constructed of planks of treated timber, 22mm x 150mm x 2400mm. No windows were considered as a security measure. I’ve added a roll of “Building Paper” to the shopping list which should make it more watertight and damp resistent.

With 2400mm length the planks will fit onto to 100mm posts perfectly. If they need additional bracing this can be added inside using simple 2×3 studding.


I considered a number of options but decided on box section painted steel sheeting to give strength and long lasting weather protection. The supplier has an option to add a membrane to the underside of the sheets which will absorb condensation which I think is a sensible precaution. I decided to add a single 1 metre wide clear roof panel to provide additional light in the shed. As this is a potential weak spot, some kind of secondary security system may be needed underneath it.


Next steps: Order materials and start the build!