Preparing a Shed Base

So, you need some more storage space. Or perhaps you're sick of cluttering your back door with garden tools, or need a more secure home for them. Well, a Garden Shed certainly solves that problem! You can browse a variety of garden sheds and other buildings here
But now you have to decide where to put it to maximise its use and make sure it stays as fresh as possible. A few key points to consider are:

1. Ground level - Is the area you are going to use suitable? If the area sits in two feet of water for half the year, then probably not.
2. Tree cover - Trees not only shed leaves, which help keep your roof damp and increase the chances of rot, they can drop limbs in strong winds. Also, any small surrounding trees will one day be big surrounding - or even imposing - trees.
3. Access - Can you easily get to and from your shed, without it blocking the view of your garden from your house? Also, all the base preparation in the world won't make it possible to get an 8 foot square panel through a 6 foot doorway, so make sure you can get the building to the site!

Once all these factors are considered, the type of base should be decided upon. Lets start with the cheapest, simplest and most practical method (after all, you're never going to see it again):
Dry Base
This consists of dry sand, with concrete flagstones laid on top. You can either mix some cement into the sand, or use a grit sand on its own which once compacted won't move anywhere.
The method is to dig out the turf on the area you wish to lay your base on. Give yourself an extra few inches all around, as you will have to get your hands around to put the flags down.
Once the turf is gone, make sure the soil beneath is suitably firm. If it is not, you may have to put some hardcore (crushed stone) down and compact this. Alternatively, you could use landscaping fabric on the soil and put the sand directly on top. This will prevent the sand and soil mixing while you work on it.
Next, spread the sand across the area at a depth of around 2 inches. Try to level it out as best you can with a rake or straight edge.
You can now start laying the flagstones. Work from one corner, and check each one for level as you lay them. Use a rubber mallet to tap the flags down firm on the sand, and make sure they are level. (Tip - Raking the sand into even ridges with your fingertips makes it easier to bed each flag properly)
Once all the flags are laid, check across the whole base with a straight edge to ensure it is level. Do not walk across the flags, this method is designed to have weight spread across the entire base evenly. If you put pressure on individual flags, you will find they can easily drop in the corners.
Concrete Base
A solid concrete base is a worry free but slightly more expensive method of providing a shed base. For a solid slab concrete base:
Once again, cut turf from the area you require. Cut slightly deeper this time, as you want a decent depth of concrete, preferably 4-6 inches. Give yourself a few inches again all around.
Using timber, create a form-work to the size you require. allow at least one inch extra all around than the size of your base.
Using wooden pegs, secure the form-work along one edge. Now using a tape measure, measure from corner to corner and make sure your base is square, and fix using more pegs. (Tip - Use more pegs than you think you need - concrete weighs a lot and will cause the timber edges to bow if not properly supported!)

Once base is square, check it for level all the way around. The best way is to start at the highest point and chase yourself back to that point, fixing the form-work to the pegs with large nails or screws. Double check for level!
Now, providing there aren't any gaps underneath your form-work edges, you are ready to concrete. Fill the form-work, and use a long straight edge piece of timber to tamp the concrete. This means you start at one end, and tap up and down on the concrete while moving along to get any bubbles out. Repeat this process a few times to make sure you have no bubbles/voids.
Now, using the same piece of timber, start at one end and gently scrape the timber along the length of the base while moving from side to side. If you find there are holes appearing in the surface, scrape some concrete from a high point and fill them in. Repeat the process until you have a smooth surface.
Cover the concrete with a waterproof sheet and allow to set.