How Much Product Do I Need?
Project Guide – Setting Posts and Poles
Checking your local building code requirements is a critical first step whether you’re doing a simple project, like installing a mailbox, or a more involved job, like building a fence.
The most important detail to focus in on and confirm is hole depth, which varies based on the frost line in your region. It’s crucial for you to dig about 6’ below the frost line to avoid frost heave.
With that technical detail confirmed, it’s time to get to work.
- Calculate the width and depth of your post hole(s).
- Recommendation for width—hole should be about 3x the width of your post.
- For example, a 4” post will require a 12” hole.
- Recommendation for depth—hole depth should be about 1/3 of the height of your post above ground.
- For example, a 6’ tall fence requires a 2’ deep hole and you’d need an 8’ piece of lumber. And an 8’ tall fence requires a 36” deep hole, so you’d need a 12’ piece of lumber.
- Calculate concrete requirements using the Sakrete App, Post Hole calculator or long hand.
Digging and Prepping the Post Holes
- Mark the diameter of your hole(s) in the soil to use as a visual reference.
- Start digging!
- It helps if you try to create an inverted cone—bottom wider than the top—for best results. Vertical edges are okay, but a cone with the bottom narrower than the top is not.
- Pour a 4” – 6” layer of gravel in the hole to improve drainage—it’s crucial to avoid wood rot, even with treated posts.
- Using the bottom of your post, compact the gravel layer.
Setting Posts – No Mix Method (Only acceptable with Fast Setting Concrete)
- Place post in the hole, approximately centered and plumb.
- Have your partner fill the hole approximately 1/3 full of water.
- Wearing respiratory protection, pour the dry mix into the hole, working evenly around the post.
- Add enough mix to come up to the top of the post hole.
- If top of mix is dry, add additional water—don’t worry, over-watering is not an issue in this application.
- Ultimately the concrete should slope down and away from the base of the post to ensure proper drainage. Backfilling with dirt can cause premature rot.
- Ensure the post is plumb by checking level on both the x and y axis (front/back, left/right).
- Hold post steady for approximately 3 – 5 minutes until Fast Setting Concrete reaches initial set. At this point you will not be able to reposition the post any further.
- Make sure to wait 30 minutes before putting any load on the post.
Project Tip: Adding water FIRST is crucial – concrete will not hydrate evenly if water is added on top of dry mix, leading to lower strength and higher likelihood of post movement.
Setting Posts – Mixing & Bracing (Used with all other types of concrete)
- Mix concrete in a mixer or wheelbarrow following the directions on the packaging. See our Concrete Mixing Guide for tips.
- Place post in hole, approximately centered and plumb.
- Have your partner pour wet concrete into the hole, working evenly around the post.
- Use a piece of scrap lumber, shovel or other tool to help remove air bubbles and consolidate the mix as you pour.
- Add enough wet concrete to come up to the top of the post hole.
- Ultimately the concrete should slope down and away from the base of the post to ensure proper drainage. It’s important to note that backfilling with dirt can cause premature rot.
- Ensure the post is plumb by checking level on both the x- and y-axis (front/back, left/right).
- Once you have found plumb, have your partner brace the post. Secure scrap lumber to the post using screws or nails, ensuring that the post stays plumb on both the x- and y-axis.
- Wait 24 hours before putting any load on the post.
Ultimate Strength And Durability
Enter An Email To Send These Results.