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Deck Support Columns

How to Install Wood Deck Support Posts

In the past, many decks were built with 4x4 support posts (also called structural posts). But these can bow seriously, even if a deck is only 3 feet off the ground. For that reason, we strongly recommend that you use 6x6s instead, even if your building department does not demand them. And if a deck is over 10 feet tall, you should install bracing.
 
This article shows installing non-notched posts on top of concrete footings that rise above the ground, to support framing that has already been built on temporary supports. 
 
[tip] Wait for the Concrete to Cure
 
Allow at least two days for the concrete to cure before drilling holes and installing a post. If you install the post the same day as you poured the concrete, the footing could crack.
 
 
Mark the post’s corner on the footing.
PinterestSave
Mark the post’s corner on the footing.
1. The support post’s side should be flush with the outside of the beam or doubled header.
Draw the outline.
PinterestSave
Draw the outline.
Use a level to mark the post’s corners, then use a square or straightedge to mark its outline.
Heavy-duty hammer drill.
PinterestSave
Heavy-duty hammer drill.
You can try to drill holes in concrete with a standard 3/8-inch drill, but it will be very slow going. Save yourself time and energy by using a standard-voltage heavy-duty hammer drill like this one, which will bore down with ease.
Sleeve anchors.
PinterestSave
Sleeve anchors.
Use sleeve anchors of a size recommended for your post base. The packaging will tell you the size of the drill bit to use, as well as how deep to drill the holes.
Mark for the hole.
PinterestSave
Mark for the hole.
2. Position the post base as shown with its inside area aligned with the pencil lines.  Scribe a circle where the base’s lag screw will go.
Drill the Hole.
PinterestSave
Drill the Hole.
Drill a hole of the recommended size, a half inch or so deeper than the sleeve anchor. Pull out most of the dust by lifting the drill bit quickly as you drill, two or more times.
Tap the anchor in.
PinterestSave
Tap the anchor in.
3. Reposition the post base, aligned with the layout lines, and tap a sleeve anchor down into the hole.
Tighten the bolt.
PinterestSave
Tighten the bolt.
Use a crescent wrench or a socket wrench to tighten the nut, which will cause the anchor’s sleeve to expand so that it grips the concrete firmly.
Measure for post
PinterestSave
Measure for post
4. Install a post cap, also called a post-to-beam connector, onto the beam or doubled joist above; use a level to be sure it is plumb with the post base.
Tap in the post.
PinterestSave
Tap in the post.
Measure the distance between the two hardware pieces, then subtract 1/16 inch or so to account for imperfect cuts. 
Use a hand sledge to tap the 6x6 into place, check for plumb, and drive nails into all the hardware holes to secure the post.
Finish with nails.
PinterestSave
Finish with nails.
Use a hand sledge to tap the 6x6 into place, check for plumb, and drive nails into all the hardware holes to secure the post. With the posts in place, you can remove the temporary supports.
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Deck Support Columns

How to Install Wood Deck Support Posts

In the past, many decks were built with 4x4 support posts (also called structural posts). But these can bow seriously, even if a deck is only 3 feet off the ground. For that reason, we strongly recommend that you use 6x6s instead, even if your building department does not demand them. And if a deck is over 10 feet tall, you should install bracing.
 
This article shows installing non-notched posts on top of concrete footings that rise above the ground, to support framing that has already been built on temporary supports. 
 
[tip] Wait for the Concrete to Cure
 
Allow at least two days for the concrete to cure before drilling holes and installing a post. If you install the post the same day as you poured the concrete, the footing could crack.
 
 
Mark the post’s corner on the footing.
PinterestSave
Mark the post’s corner on the footing.
1. The support post’s side should be flush with the outside of the beam or doubled header.
Draw the outline.
PinterestSave
Draw the outline.
Use a level to mark the post’s corners, then use a square or straightedge to mark its outline.
Heavy-duty hammer drill.
PinterestSave
Heavy-duty hammer drill.
You can try to drill holes in concrete with a standard 3/8-inch drill, but it will be very slow going. Save yourself time and energy by using a standard-voltage heavy-duty hammer drill like this one, which will bore down with ease.
Sleeve anchors.
PinterestSave
Sleeve anchors.
Use sleeve anchors of a size recommended for your post base. The packaging will tell you the size of the drill bit to use, as well as how deep to drill the holes.
Mark for the hole.
PinterestSave
Mark for the hole.
2. Position the post base as shown with its inside area aligned with the pencil lines.  Scribe a circle where the base’s lag screw will go.
Drill the Hole.
PinterestSave
Drill the Hole.
Drill a hole of the recommended size, a half inch or so deeper than the sleeve anchor. Pull out most of the dust by lifting the drill bit quickly as you drill, two or more times.
Tap the anchor in.
PinterestSave
Tap the anchor in.
3. Reposition the post base, aligned with the layout lines, and tap a sleeve anchor down into the hole.
Tighten the bolt.
PinterestSave
Tighten the bolt.
Use a crescent wrench or a socket wrench to tighten the nut, which will cause the anchor’s sleeve to expand so that it grips the concrete firmly.
Measure for post
PinterestSave
Measure for post
4. Install a post cap, also called a post-to-beam connector, onto the beam or doubled joist above; use a level to be sure it is plumb with the post base.
Tap in the post.
PinterestSave
Tap in the post.
Measure the distance between the two hardware pieces, then subtract 1/16 inch or so to account for imperfect cuts. 
Use a hand sledge to tap the 6x6 into place, check for plumb, and drive nails into all the hardware holes to secure the post.
Finish with nails.
PinterestSave
Finish with nails.
Use a hand sledge to tap the 6x6 into place, check for plumb, and drive nails into all the hardware holes to secure the post. With the posts in place, you can remove the temporary supports.
Popular Framing Articles
VIEW MORE Framing ARTICLES
Brick Decorative Columns
PinterestSave
Deck Support Columns

How to Decorate Deck Support Columns

Browse some examples of decorative deck support posts for tall decks.

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Installing your decking at a 45-degree angle is a popular style for decks. This can be done to reduce decking seams or just for appearance.

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Looking for Decking Materials Near You?
Find the best deck boards and supplies in your area
By clicking FIND A RETAILER, you acknowledge that you have read Trex's Privacy Policy.
Related article topics
Icon Footings Icon Decking Icon Ledger Icon Framing Icon Stairs Icon Railings Icon Features Icon Design Icon Planning Porches & Patios Icon Care Icon Materials
VIEW ALL TOPICS
Get more helpful resources delivered right to your inbox

Explore Articles by Topic

Footings

Footings

Information related to installing frost footings for decks

Framing

Framing

Learn structural framing methods

Decking

Decking

Learn about wood and composite decking materials

Stairs

Stairs

An in-depth look at the complex issue of how to build stairs

Railings

Railings

How to install guardrails and handrails to meet IRC code

Features

Features

An overview on water drainage, benches, planters and lights

Design

Design

The basics of deck design

Planning

Planning

Learn about permits and working with contractors

Porches and Patios

Porches & Patios

Build a covered deck to enjoy all seasons

Ledger

Ledger

Proper attachment techniques

Care

Care

Maintain your deck to maintain your investment

Materials

Materials

An overview on water drainage, benches, planters and lights

More Helpful Resources

Ctas Features 1 Deck Plans@2X

Professional Deck Plans

EXPLORE THE DECK PLAN LIBRARY >
Ctas Framing 2 Joist Span Estimator@2X

Joist Span Estimator

CALCULATE JOIST SPAN >
Resource Card DIY Guide

Step-by-Step DIY Guide

LEARN HOW TO BUILD A DECK >