How to anchor post to concrete

Mr. HowToSpecialist December 7, 2011 Comments Off
How to anchor post to concrete

This article is about how to anchor post to concrete. This diy step by step project project is very useful, as when building a deck, a railing or a fence, you need to anchor posts to concrete. The techniques needed to attach the wooden posts to concrete are straightforward, as anyone can get the job done very quickly. First of all you have to buy the post, as to know its dimensions when buying the hardware post anchors.

The post anchors come in many forms and dimensions: from standoff post base, up to uplift post base. In addition there are regular post anchors, for home improvement projects, and heavy duty post anchors for greater stability. Irrespective of your needs, you also have to know that there are also adjustable anchors, for attaching posts to an unleveled concrete surface. They are more expensive, but at least you know you are able adjust the height of the posts, as to make sure they are perfectly aligned one with another.

In order to anchor post to concrete, you need the following tools and materials:

Materials:

  • 4×4 lumber         – Posts
  • post anchor        - Metal Anchors
  • 2-3” lag screws  - Lag Screws
  • plastic dowels    - Dowels
  • wood primer      - Primer

Tools:

  • Level, measuring tape, framing square, carpenter pencil
  • Hammer, rubber hammer
  • Circular saw
  • Drill machine and drill bits
  • Electric screwdriver with torque control
  • Brush, C-clamps

Tips:

  • Read safety and disclaimer pages
  • Select with great care the wooden posts, to match the railings design
  • Use a good drill machine with torque control
  • Before fastening the posts, make sure they are plumb

 

Installing post anchor

Anchoring post to concrete

Anchoring post to concrete

In this project, we show you how to anchor post to concrete. In our case, we had to build stair railings and consequently we needed to attach post to concrete.

First of all, you have to take a look on the concrete surface, as to see if it is level. If the concrete flooring isn’t level, then you have to buy adjustable post anchors. Although they are more expensive than regular post anchors, they will allow you to adjust them to the other posts.

Building wooden post

Building wooden post

Next, we have to build the wooden post, that we want to anchor to the concrete platform. Consequently, you could either buy 4×4 pressure treated lumber or buy fancier decorative posts. Irrespective of your choice you have to adjust them to the needed length (usually around 3′/1 m), before fitting them into place.

Smart tip: Use a L-shaped square and a carpentry pencil to draw cut lines on posts. Work with great care and good judgement, in order to obtain a professional result.

Cutting wooden post

Cutting wooden post

In order to cut the wooden posts we have to use either a circular saw or a wooden chainsaw. We strongly recommend you to use a good circular saw, as it is better for an unexperienced diy-er. We have used the chainsaw, as we were pressured by time.

Smart tip: Before cutting the posts, make sure they are locked firmly into position, otherwise you risk damaging the wooden posts or injuring yourself.

Marking where to install post anchors

Marking where to install post anchors

After you have adjusted the post to the needed dimensions, you have to install the post anchors to concrete. Consequently, in most of the cases the metal anchors have to be fastened to concrete, with several plastic dowels and lag screws. Align the anchors one with another, before making the marks.

Smart tip: Before driving in the screws, we have to use a carpentry pencil to mark the places where we will dill several holes. Make sure they are visible, and the post is aligned properly with your platform.

Drilling holes to anchor the post

Drilling holes to anchor the post

In order to dill holes in concrete, we used a good drill machinery and masonry drill bits. Make sure the drill bits are in good condition, otherwise you might damage the drill machinery.

Smart tip: The drill machinery must have hammering function, otherwise you won’t be able to drill in concrete and anchor the post. Hold the drill machinery like a gun, with one hand on the holder, while the other one gives you a good control while drilling in concrete.

Installing dowels in concrete

Installing dowels in concrete

After we have drilled the holes in concrete, we have installed plastic anchors, using a rubber mallet. Make sure the heads of the dowels are aligned with the concrete surface, otherwise you won’t be able to install the post anchor properly.

Smart tip: The size of the plastic dowels has to match the one of your screws, otherwise they will break while you drive them in. In addition, you could also use expansion shields instead of plastic dowels, for a better support.

Installing post anchor

Installing post anchor

Next, after we have inserted the plastic dowels in holes, we have to drive in the screws , as to fasten the post anchor. In order to lock into position the metal hardware, we used a wrench key and 3” lag screws.

Smart tip:  For extra strength use washers for every screw yu drive in concrete. In addition, you can avoid drilling holes and inserting the plastic dowels, by choosing to use self-tapping screws for concrete. Just make sure you ask a professional from your local diy store, when buying the screws.

 

How to anchor post to concrete

Anchoring post to concrete

Anchoring post to concrete

After you ensure the post anchors are locked into position, you could proceed to installing the wooden posts. Consequently, in order to anchor  a post to concrete, you need to paint its bottom section with wood primer, as to make sure it will resist against moisture. Sand the bottom section with a band sander, it it doesn’t fit in the anchors.

Attach the post in the anchor, tapping it slightly with a rubber mallet, until it sits properly into position, but don’t drive in the lag screws yet.

Smart tip: Use a level to check if the wooden  post is plumb. If you notice that the post isn’t plumb, then you have to bring it into the right position, and to lock it with several clamps and two braces. Use again the hand level, in order to make sure the post is perfectly plumb.

Using a wrench key to drive screws

Using a wrench key to drive screws

Use 1 1/2” lag screws to secure the post into position. Consequently, the last step when anchoring a post to concrete, is to drill pilot holes with a drill machinery through the holes in the post anchor. Use a thin drill bit, otherwise the lag screws won’t secure properly the post.

Smart tip: Use a wrench key to drive the lag screw in the pilot holes. Do not apply too much force, otherwise you risk damaging the post (the wood might split). Insert the second screw on the opposite side of the anchor.

Attaching post to concrete

Attaching post to concrete

After driving in the lag screws, we have finished anchoring a post to concrete. The wooden post is plumb, as we have used a spirit level, and it is secured properly with 4 lag screws. There are many types of anchors you could use for your project, therefore use the ones that fit your needs an match the rest of your backyard.

Smart tip: In order to make sure the post is plumb, you could use a post level, a tool which reads in both directions at once. In this manner, you could save time and get the job like a pro.

 

Thank you for reading our article on how to anchor a post to concrete and we recommend you to check out the rest of your projects. Don’t forget to share our projects with your friends, by using the social media widgets.

 Related projects: 

 How to build deck railings

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