A new potting shed, storage shed or summerhouse can be a wonderful addition to a property. However, many people who purchase ready made timber outbuildings do not make provision for supporting them and protecting them from moisture and overturning.
Here are a few tips for managing the installation of a shed or other small timber building if a base has not been prepared in advance, or if a very simple solution is needed. Of course, concrete or treated wood supported on a free-draining gravel base will perform better than most of these options, and a true concrete foundation is best of all.
A shed or outbuilding can be placed on existing pavement or tarmac. Sound pavement should be able to support the weight of a small outbuilding. Sinking adhesive or expansion bolts into the surface can tie the shed down. However, there will still be drainage and moisture control issues to consider.
If the deck is strong and sound, then it should be able to support a small outbuilding. A timber shed or summerhouse can simply be screwed down to a wood deck. Anchor it directly to joists and other supports, if possible, and not just to boards.
It's always best to put the outbuilding onto a level surface. A long, straight piece of timber and a four foot long spirit level can reveal whether a given area is level.
Put the shed on high ground, if possible. Place it somewhere water will tend to drain away from. If possible, create a level surface for the shed, with the ground sloping away from all of its walls. If one side of the outbuilding has a slope directed toward it, then find a way to route water around the shed. For example, use well secured roofing material, polyurethane sheets and/or metal flashings.
If the bottom of the shed is untreated wood, then provide it with moisture protection. For example, paint it, treat it, and/or cover it with polyurethane that's sealed against the bottoms of the walls and will not let water in at the sides.
You will need to tie down your shed to prevent it from tipping or being moved by high winds. Tie down kits are available for sale online and from building supply merchants. Even large tent stakes can work in a pinch, for a small building. The type of tie downs that will be effective depend on what's under the outbuilding.