How to build a shed

Sheds come in all shapes and sizes, from tiny storage units to large multi-purpose structures. Typically sheds sit in a back garden or on an allotment and are simple, single-storey structures. Sheds do however vary considerably in the complexity, from small open-sided constructions to large wood-framed units with windows and an electrical supply. Here we will go through a step-by-step guide on how to build your own shed, but you can vary all dimensions so you get the right shed for your specific location.

How to build a shed step-by-step guide

Here we go over the steps to create a 12ft by 8ft simple square shed. This is a standard size, but you can modify the dimensions to suit your needs.


It’s important that you build your shed on level and solid ground, so if your ground is not level you will need to either use a bit of brute force to hammer the loose earth flat, or better still you can lay concrete foundations on to which you construct your shed. We have a guide for 3 different methods for creating your own foundations, check it out by clicking here.

An alternative and popular method is to use deck piers onto which you lay your joist spans for a floor of the shed. If you have a level and solid foundation you can use purpose built pre-formed supports as show in Figure 1, or you can dig holes into the ground to place support posts, and fill then with concrete to form a solid base. Whichever method you use you should lay your deck piers out in a simple grid format, as shown in Figure 2.

Deck Piers
Figure 1 Purpose built concrete deck pier supports.

deck pier layout grid for a shed
Figure 2 Layout of supporting deck piers for your shed base.

Add support beams across the deck pier support posts, which will be the support for the floor joists. 3 x (12 ft x 4 inch x 6 inch) beams are good. You can use a 1 inch metal strap to attach the beam to the deck pier support posts or carefully fix with nails. See Figure 3 below.

deck pier supports for building a shed
Figure 3 Support beams for the floor joists.

Next you need to attach the floor joists across the support beams. You can use nails to do this. The first job is to fix an outer rim joist to the 2 edge beams, and then you can start laying a series of joists at 90 degrees to the support beams. See Figure 4. You should carefully measure the distances between the joists, for both the end stability of the floor an to ensure standard plywood lines up nicely with the joists. Along the centre support beam you should place a 14.5 inch piece of ‘blocking’ wood to ensure equal spacing and also to stop any movement between the joists.

support joists for floor of shed
Figure 4 Fixing joists to the support beams.

Now the framework for the flooring is down, you need to cover it with plywood. 3 standard sheets of 4 ft x 8 ft plywood will cover the whole floor. One of the sheets is cut in half and the other 2 are put down whole. You do not want a straight line across the middle of the flooring in the direction of the joists because this will cause a weak point in the floor. You should lay the plywood out as show in Figure 5.

plywood for floor of shed
Figure 5 Attach the plywood flooring.

The next step is to build the 4 walls. The 2 sides will need a slight slope to avoid water build up when it rains, and the front will need a door.

The back wall is the easiest, and it needs to be the same width as the flooring, but should be about 6 inches lower than the front wall. So, for this example the height needs to be 7 ft 3 inches. The front wall should be very similar in overall shape, except its height should be 7 ft 9 inches tall. Also, a door needs to be framed. See Figure 6 below for back and front wall designs.

back and front walls of the shed
Figure 6 Back and front wall layouts for your shed.

The side walls need to slope, and this can be done by having vertical joists of varying height (it’s easiest to have them progressively smaller by 1 inch as they move forward from the back to the front. See Figure 7.

side wall of the shed
Figure 7 Side wall of your shed.

Now you have 4 walls you need a roof. You should place rafters across the side walls, overhanging a bit for extra weather protection. Once your rafters are secured in place with nails, you are advised to place wooden blocks between each pair of rafters to add extra security to the roof. See Figure 8.

shed roof rafters
Figure 8 Adding rafters to making the roof of your shed.

As with the flooring, plywood will be fixed to the rafters. This time 3 full standard sheets of plywood will cover most of the roof area, but you will need to cut extra strips to attach over the weatherproofing overhangs. Once in place, the plywood should be covered with roofing felt, making sure you overlap the top sheet over the bottom sheet to ensure you keep the water out if you use more than one solid sheet of felt. See as an example Figure 9 below.

felting your shed roof
Figure 9 Felting your shed roof.

There you have it, all that is left to say is good luck. YouTube is a good place to search for videos for people making sheds if you didn’t find everything you were looking for here. We hope to have our own videos soon to help you out.

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