How should I prepare my site?
A common misconception is that a shed should be elevated on cinder blocks to help prevent rot and insect damage. This may have been the case 30 years ago, however, since the introduction of pressure treated lumber and today's more durable sidings this is no longer necessary.
Crushed Stone
A crushed stone base, 4-6" deep, is one of the best ways to prepare your site. Be sure and use "crushed" stone as opposed to "pea" stone. 1/2" is a good diameter and is relatively inexpensive.
When preparing the site with crushed stone be sure and extend the size of your base 2' longer and wider than the actual size of the shed. Place your shed in the center of the pad leaving a 1' perimeter of stone around the shed. This will prevent roof runoff from splashing dirt back up on the siding causing what we like to refer to as "ring around the shed".
When digging out the area to accept the stone, start at the lowest area and establish the grade by digging down 4-6". You can now excavate the rest of the site keeping in mind the site should be level when finished.
Sono Tubes
Also known as concrete piers are recommended or even required by some towns. 10" diameter tubes are recommended. You should contact the shed builder or retailer for recommended placement.
Cement Slab
A cement slab is one of the more expensive ways to prepare your site however if done correctly it can also be the best. A slab will keep the shed level and prevent grass and weeds from growing both under and around your shed. A slab is also beneficial if you intend on storing larger items (wheel barrow, lumber, grass catcher etc.) behind or next to your shed. Increasing the size of the slab a couple feet is a good idea to accomodate these items.
Concrete Blocks
Most companies will place your shed on cement blocks or patio blocks in order to level it. Cement blocks have a tendency to settle into the ground over time and can cause the shed to fall out of level, which can hinder the use of the shed doors.
If you choose to utilize patio blocks it is a good idea to dig a trench 1 foot wide and 4-6 inches deep around the perimeter of the shed and fill it with some type of stone or gravel. This will prevent roof runoff from splashing dirt onto the siding and also keep grass and weeds from growing against the siding.
Ground
You may also decide to simply place you shed directly on the ground. Depending on the shed construction this should be fine. Be sure that the shed has a pressure treated floor system and base. It is also important that the shed has pressure treated timbers running underneath and perpendicular to the floor joists in order to elevate the shed and allow adequate ventilation."
