How to Set a Post For a Deck

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Now that you are ready to build your outdoor patio deck there are a few steps to making sure the strength of the foundation is rock solid. The deck is only as sturdy as the posts supporting it, but don't fret. Follow a few simple techniques to set the posts correctly and your deck should last a lifetime and a half.

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Instructions

Difficulty: Moderate

Things You’ll Need:

Shovel
Prefab concrete pier
60 lb bag ready mix concrete
Wood deck posts
Caisson tubing
Cardboard cylinder
Level
Screw gun
Screws
Gloves
Bucket for mixing

Set a Post For a Deck

Step1

There are two effective ways to set a deck post. Instructions for the first method include the purchase of a pre-fab concrete pier which has metal post anchors attached to each side. Dig a hole and pour into the hole a concrete base; preferably using a 60 lb bag of ready mix. Set the concrete pier into the wet concrete inside the hole. The concrete will cure around the pier adding stability.

Step2

After the concrete dries, attach the post to the pier using a screw gun and screws. Following this procedure the post is neither inside the concrete nor underground exposed to the elements. The post is attached above ground between the metal anchors attached to the pier.

Step3

The second method to setting a deck post requires the purchase of caisson tubing and a cardboard cylinder which is manufactured strictly for post setting purposes. The cylinder comes 1/8 inch thick, round, treated, water resistant and in different diameters depending upon the size of the intended deck post.

Step4

Dig a hole. Place a 2 foot piece of caisson tubing inside of the hole. Plumb the tubing with a level. If added strength is desired, include a re-bar grid inside of the hole also. Fill the hole with fresh concrete and place a prefab post anchor, purchased at any hardware store, on the top of the wet concrete. Let the concrete cure. This method provides a stronger foundation than the first, although either method will provide a solid setting for a deck post.

Tips & Warnings

Concrete is made up of sand, agrigates, portland cement, and water. The volume of each material is what determines the strength of your concrete. Check the concrete bags for ratios.
There are different sizes of pre-fab concrete piers. Make sure to buy the size that is consistent with the diameter of your deck post.
Concrete constantly sucks water out of the ground. If the deck post is set right into the wet concrete the post will always be damp, thus eventually causing the post to rot. In the summer when it is hot and dry the post will shrink leaving a gap between the post and the concrete. Rocks and dirt get in between the concrete and the post causing more damage to the post. Eventually the post has to be replaced.
Don't fall into the trap of digging a hole, setting your post inside, and filling the hole with concrete. What may seem like a good idea will eventually lead to a rotten post and a weakened deck.