How to build a shed foundation?

The concrete pad is the best foundation, but it's the most difficult to make. If you don’t have the experience, it’s best to hire someone for this job. The unfortunate reality is that rear handy-person will take on such a small job unless you also hire them for a full shed assembly…

The second best is treated wood (4x4 or 2x6) frame filled with gravel or a treated wood grid (this is more complex than the frame alone, but it's a better option for soft soil or slope location).

We generally don't recommend plain gravel foundation, as it will shift over time no matter what. 

A better option is treated 4x4 or 2x6 grid filled with gravel. You can then cover the wood grid with plywood to serve as a subfloor to extend the life of your flooring. See the images below for treated wood foundation examples.

treated wood frame filled with gravel

Treated wood frame filled with gravel

Treated wood grid on blocks with membrane and gravel to prevent vegetation growth underneath the shed

4x4 treated wood grid on gravel (not filled) for stability, and to prevent vegetation growth underneath the shed

Treated wood grid on cinder blocks with subfloor installed

2x6 grid on concrete piers - great for soft/soggy soil, or on a slope

Minimum recommended foundation

On each product page, in the measurement section, there is a line describing the recommended foundation size. It may be confusing because it is smaller than the nominal shed size but recommended foundation size means the shed walls will be flush with the foundation perimeter and the interlocking corner “paddles” will be hanging off the foundation. This is the most aesthetically subtle option. See the images below. 

Shed built on a larger than minimum foundation

Shed built on the minimum recommended foundation

If you have any questions, comments or suggestions based on your own experience, please share! We always appreciate good tips, and photos illustrating your solutions. Email us at