How Short Can Deck Posts Be? (What You Need To Know For Lower Decks)

When it comes to building a low deck, most often, it’s not a matter of choice. Sometimes, you just have a low back door and a floor that is almost level with the ground. There are ways to get it done, however, how short can your deck posts be?

They shouldn’t be any shorter than ten inches unless you’re willing to compensate with a larger concrete pier. The smaller you go on your post size, the odds increase that you will end up splitting the wood as your drill into it, create anchors, etc.

Fortunately, there is more than one way to build a deck on short posts, or maybe no posts at all, depending on what your need and the scope of the overall project.

Since you shouldn’t use posts that are shorter than 10”, you should certainly consider other options, such as using larger concrete footers or building a floating deck.

Piers Instead of Short Posts

Many deck professionals would advise you not to bury your posts in concrete or, at least not to a large degree. As in everything, the process for building a deck has evolved over the years and there are at least 4 ways to pour a concrete pier that would be ideal for beam-to-pier framing.

Bell-Shaped Piers

Bell-shaped piers have a good, low center of gravity since the majority of the weight is on the bottom of the pier. It does require you to dig a wider area to accommodate the bottom and since the pier narrows as it travels upwards, you will need a good mold to shape the concrete as your pour.

Usually, the posts are buried in this type of pier and that’s ok, to a degree, so long as you exceed 10” in the total length of the post. With a pier this size, however, you shouldn’t have any problems doing so.

Your 4 x 4 or 6 x 6 post will protrude from the top of the piers and the top of the pier will end a few inches above the ground. In this way, you avoid allowing the post to come into contact with anything below ground level as the concrete encasement will protect it under the ground.

Straight Pier with a Flat Footing

The same level of digging depth applies here and you can even use a bell mold as you would for a traditional bell pier, however, when it comes to this pier, there’s the addition of a long cylinder that extends up above the bell form.

Like the bell form, the straight pier with a flat footing is designed to spread the weight of your deck outward, since it too has a low center of gravity, with the vast majority of the weight spread out at the bottom of the pier.

You can finish this pier well above ground level, as far as you need it to be, and bolt your beam directly to the pier.

Straight Concrete Piers

These are probably the most frequent type of piers that are used in backyard deck buildings. The hole that you dig in the earth is your cylinder mold but you will need a synthetic mold above ground level so that you can finish the pour a few inches above the ground.

Like the bell or the bell bottom, you can bolt your beam directly to this pier and, while it’s not on the same level as the bell piers, in terms of weight distribution, its more than enough to handle standard and even large deck loads, as long as you pour enough of them.

Concrete Footing

This pier is probably not going to be what you are looking for in a short deck, however, instead of the cube-shaped footing that this pier is designed with (the pier is well below the ground by the way), you can use 12 x 12 cube molds.

Pour your concrete into the molds and give it time to cure. In the meantime, dig your holes in the yard where your deck is going to end up. Be sure to dig wide enough and deep enough to accommodate each cube.

You will want to allow the cubes to stand above the ground by an inch or so don’t dig too deeply. When you have the cubes all in place, you can start building your deck up from there, without the need for any posts.

You will have plenty of surface area to lay your beams down and anchor them with the appropriate brackets before laying out your joists and eventually, your decking. It’s not the best method for exceedingly large decks as there will be a deal of “settling” into the ground over time, with all of that excess weight.

Small Platform Decks

To avoid the use of posts altogether, you can go with a small platform deck instead, assuming that you are keeping everything small. Instead of pouring piers and building up from there, you can simply carve out two channels.

These two channels are 6 inches deep and will run the length of your deck. You can either fill four inches of each channel up with sand or concrete, plant one 4 x 6 in each channel, level them, and mark them for your joists.

Once your joists and rim joists are installed, then you can proceed with your 2 x 6 decking. Of course, this is a very simple layout and just a suggestion for keeping your deck low to the ground without the addition of posts.

When you have to build low, there are more than just small platform decks out there and the above example is essentially how you would construct a floating deck as well. It all depends on how low your back door is to the ground.

Final Thoughts

So, while going with posts that are below 10” is not a good idea, there are still plenty of ways for you to construct something low to the ground. It means replacing most of your foundational framing with concrete, but it will also ensure that your structure is neither too high, nor low enough to sit in standing water.

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How Short Can Deck Posts Be? (What You Need To Know For Lower Decks)