Yes, you can build a deck directly on the ground. There are many reasons to want a very low deck, including that at certain heights the deck may not require stairs or guardrails. However, building a deck so low requires unique design and installation as direct contact with the ground changes the environmental stresses on the deck’s material and changes the way that the deck will bear weight. We’ll walk you through some of the things you should consider when building your deck directly on the ground.
Your Building Codes
As with all home improvement projects, it is wise to look into your local building codes before you start. In this case, it is wise to look into it for two reasons. The first is to determine what your code considers a “ground-level deck” and whether you are allowed to build it.
In California, it is most likely that your building code considers any deck built until 24 inches to be a ground-level deck. You should see whether these are allowed, especially if there are stipulations for decks under eight inches high, which is usually what homeowners mean when they want a ground-level deck.
Then, determine if your ground-level deck needs stairs and railings, as per the building code. It may also include other stipulations about low decks.
Materials for Ground Contact
Wood reacts differently to the moisture in the ground than it does to the moisture in rain or the air. Being in contact with the ground can speed up the natural decay process of the wood. Wood is considered to be in contact with the ground if it is within six inches of the ground. This wood will need to be specially treated for ground contact. Most pressure-treated lumber at your average local store will not fit the bill. You need to purchase a specialty wood or composite material for this purpose.
If you do not want to make the whole deck structure out of this material, you can raise the deck up so that there are more than six inches between the beams (floorboards) and the ground. Then, you can use a typical deck material. However, the support wood that is in the ground should still be made of ground contact material.