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4×4 vs. 6×6 Deck Post: When to Use Each One Effectively

Imagine sitting on your front deck, drinking a glass of sweet tea on a sunny spring afternoon. Gathering friends and family members together to join you for an evening of porch sitting is a favorite pastime for many people.

However, the first step requires you to build the framework for a sturdy deck. What types of materials will you need to build the porch of your dreams? Understanding the differences between 4×4 vs. 6×6 deck posts is key to making all other decisions about your front porch.

If you’re ready to start planning the building phase of your new deck, this guide contains everything you need to know about whether to choose 4×4 or 6×6 posts for a deck.

Size of the deck

According to building codes, there is no clear answer on when you should install a 4×4 vs. 6×6 deck post. However, experienced contractors will tell you that a 4×4 post simply can’t carry the heavy load that many porches require. Most professionals will encourage you to consider going with a 6×6 deck post form the outset of the project.

If the deck is going to be built near grade, contractors may feel comfortable opting for the smaller post sizes. Decks that are going to be built higher than just a few feet off the ground will likely need something more substantial than a simple 4×4. Despite the fact that the code may not require it, most contractors and handy homeowners would feel more comfortable with a heftier 6×6 post to support the deck.

The length of the posts can also influence which size post will work best. As the lengths reach to eight feet or longer, you should highly consider upgrading your posts to a 6×6 size. In this particular case, it is due to the potential warping of a 4×4. These smaller sizes are more likely to bend over the course of the year, creating major structural issues that could jeopardize the safety of you and your family.


Another key factor in making the decision between 4×4 or 6×6 posts for a porch is the weather. Some climates tend to see more snow and ice during the winter months.

Depending on the pitch of your roof and the overall temperature of the air outside, you might end up with a lot of buildup throughout those long winter weeks. This can put a tremendous load onto the roof of your porch. Unfortunately, a 4×4 post may not be able to withstand the weight, causing the entire porch to buckle.

A 6×6 post gives you a little more long-term stability, particularly in those colder climates. Not only does it perform better when carrying heavier loads, but it also makes the heading for your roof more secure.


Of course, a 6×6 post for the deck has a few other benefits beyond just its load-bearing abilities. One of the major issues with a smaller post for the deck is notching the board for headers, rim joists, and other items. A smaller post is all but carved away when you take this notching into consideration. Meanwhile, a 6×6 post still has some room to spare when all is said and done.

Some people may argue that you could simply bolt the header boards to the 4×4 post instead of notching it. This can be a relatively tricky concept and may not pass your local county inspection. Choosing to install the headers with just bolts means that you rely on the connector’s strength to hold up the header of your porch.

On the other hand, notching gives you the security of having the entire beam hold the header up. It does require a little bit more wood and more space to create notches for these boards, but you have infinitely more stability and support. It most likely is not worth the risk for you to attempt to fasten such an integral part of the porch with bolts when it could be supported with a proper 6×6 post.


When it comes down to it, many people are tempted to base their final decision between a 4×4 vs. 6×6 deck post on the overall cost of the finished job. However, this may not be able to help you decide.

The cost difference between a 4×4 deck post and a 6×6 version is relatively nominal. The added security that you gain from purchasing a 6×6 post is worth far more than the fairly minor savings that you would get for choosing the smaller post size.

Choosing the right post for the job

While there may be a handful of circumstances that only require the minimum 4×4 deck post, you will more than likely want to choose a 6×6 post for the deck. It provides more stability for larger decks, the ability to hold a heavier load, and more room for notching. Given that the price difference tends to be minimal, the choice between these two post sizes is clear.

Mike Bailey