A proper base is important for your shed, gazebo, or garage for two main reasons:
- The structure needs to sit on a solid, level surface to remain stable and for the doors and/or windows to operate properly.
- The structure needs to sit slightly off the ground to allow for proper water drainage and minimize moisture transfer from the ground to the structure.
There are several types of shed foundations, and the kind you need may depend on where you live, the size of your shed, and its intended use. The following are the most common methods:
Our recommended base is ¾ inch clear stone, to a depth of 4-6 inches minimum. This can be above or at the existing ground level. If the base is level and the slope onto the pad is not too steep, we will not have a problem getting your shed onto the pad.
We also recommend that landscape material be placed prior to the stone to prevent weeds, etc. from coming through.
Pictures of the completed pad and access area are required prior to delivery. There can be no obstructions along the path to the pad or on the pad, meaning branches must be trimmed back. Detailed pictures of the delivery path are expected as well, all slopes need to be identified and documented. Delivery cannot and will not be scheduled until pictures are received.
Option 1: Clear Stone Pad
To prepare a clear stone pad, plot the foundation with at least two feet wider than the building, plus extra space for a ramp. For example, a 10’ by 14’ building would require a stone pad of at least 12’ by 16’. This allows for better drainage around the perimeter of the shed for rain/snow melt dripping off the eaves. This will prevent water from splashing.
Within the boundaries of the shed foundation itself, turf and soil should be removed to a depth of at least four inches. That dug-out space should be square and level.
Place landscape material, topped with ¾ inch clear stone raked level (does not need to be compacted). When the gravel pad is finished, your shed floor joists can then rest directly on top of the clear stone.
Option 2: Timber Box
A timber box can be built from pressure-treated 4” by 4” lumber, if desired. Its inside dimensions should extend about a foot beyond the outside perimeter of the shed on each side. The top layer of lumber can be flush with the highest point of the site. All sides of the timber box should be made level and anchored to the ground with rebar. Any turf and loose soil should be removed from inside the timber box.
Clear stone (¾”) should be used to fill the dug-out space, then raked level to a gravel depth of at least four inches throughout. When the gravel pad is finished, your shed floor joists can then rest directly on top of the gravel.
Option 3: Patio Blocks
This only applies to a shed with two runners, as you will be able to access the patio blocks and level them with shims after the building is in place.
Setting the shed on patio blocks is the most economical option, where 1” thick, 12”x12” patio blocks are placed under each runner, at three-foot intervals.
The building gets placed onto the patio blocks, then it is jacked to a level position and the blocks are then shimmed so the building rests fully supported on the blocks.
Note: Patio blocks are to be used in this option, NOT cinder blocks. Inevitably, there will be some settling after your shed is delivered and placed on site. Placing a shed on cinder blocks greatly increases the risk that your shed will settle unevenly. This can create twisting and offset door and window frames. Additionally, delivery and placement of the shed can be made more difficult with cinder blocks as a base.
Even experienced DIYers may have questions or encounter challenges when building a shed foundation. Therefore, we recommend hiring a qualified building professional.