HOW-TO GUIDES

How to Install Deck Frame Beams and Posts

 

Our How-To Team will take you through the process of proper attachment and installation of your deck's ledger board, posts and beams.

 

Disclaimer: Instructions provided by Trex® are based on the build specifications that Trex® demonstrated in the Trex® Academy video series and are not universal to all homeowners’ projects. A homeowner’s build may vary from Trex’s instructions based on the homeowner’s local municipality requirements, individual design preference and project specifications. For questions or assistance needed during your project, please reach out to howto@trex.com

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12-20 Hours with a Team of Two*
*Timing is estimated for a 14'x22' deck less than 48" off of the ground with two workers with intermediate carpentry skills. Estimate includes installation for all posts used in the deck plan for this video as well as 2 rows of beams. Times may vary based on the complexity of the shape and features of the deck.
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Step-by-Step Instructions
Chapter 01: Ledger Board Placement at the House
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So you're ready to get started? Watch our how-to tutorial before you start your build.

Before you begin any DIY project, make sure to wear the appropriate personal safety equipment. Eye protection, ear protection, gloves, long pants, a long-sleeved shirt, and reinforced toe shoes are recommended. Always make sure that you have a first aid kit nearby. For any home project, be certain to follow local code and permitting requirements. 

 

Step 1

Ledger boards can be placed in two potential positions.

The first placement option entails placing the ledger board flush with the bottom of the door threshold. This placement option will result in the deck being even with the interior floor of the house for an even walk out. In areas where there is little snow, this can be a very attractive option. 

The second placement option entails placing the ledger board below the threshold of the door. This creates a step down onto the deck when exiting the house. This step down cannot be less than 4” or more than 7 ¾” (per International Residential Code requirements) when measured to the top of the decking. When using this placement option, the ledger board is attached to the rim joist of the house. Be sure that all fasteners are in contact with the rim joist of the house and check with your local municipality to ensure that you are compliant with code requirements. This option can help prevent snow buildup at the door in areas that receive larger amounts of snow.

In this case, the original deck was built with a step-down from the house, so to maintain the height of the previous deck, the second placement option was used during this build.

Step 2

The municipality code for step height is measured from the top of the threshold of the door to the decking, and the maximum allowable height of the step is 7 ¾”. As you make your own step height measurement, be sure to stay under the maximum height requirement and mark the house to remember your distance. In this case, the desired distance of 6” was measured down from the door to the decking where a mark was made.   

Step 3

Hold a scrap piece of the decking to the mark placed on the house during Step 2. Make sure the piece of decking is level and make another mark under the piece of decking. This will be where the top of the ledger material is placed during installation.

Place a piece of scrap ledger material up to the new mark. In this case, the ledger material was 2x8 pressure-treated lumber.

Holding the scrap ledger material level, repeat the measurement process and make a mark under the scrap piece of ledger material. This mark will be used during the next installation step.    

Step 4              

Attach a small piece of 2x4 material, 4”- 8” long, to the bottom of a piece of beam material. This 2x4 material will act as a helping hand in the upcoming installation steps.

Hold the piece of scrap beam material, 2x10 pressure treated lumber in this case, up to the mark made under the bottom of the ledger material in the previous installation step.

Fasten the beam material to the wall with 3” exterior-grade wood screws. This piece is temporary so do not over-tighten the fasteners so it can easily be removed later.                                   

Drop the post into the hole on top of the footing. Refer to our Trex Academy guide “How to Install Deck Post Footings” for more information on digging the holes you’ll need here.   

Pro Tip

Using 2x4’s, construct a stand that can act as a helping hand at various times throughout the project. Use two small scrap pieces of 2x4, around 24” long, and fasten them together in a ‘T’ configuration. Then fasten a longer piece, 36”- 48” long, vertically to the side of the ‘T’ shape.     

Step 5

Find a long, straight edge to place from the ledger beam to the outer edge of the deck. This can be a 2x4 or a piece of the joist material. The only requirements are that the material is a) as straight as possible and b) long enough to reach the post that is being marked on the outer edge of the deck. The small piece of 2x4 attached to the beam material in Step 4 will be the ledge for one end of the straight edge. The other end of the straight edge will be held up by the stand that was built in the Step 4 Pro Tip.

Place the straight edge on the 2x4 block, level it, and clamp it to the stand using a bar clamp.      

Step 6                          

Level the support post in both directions to ensure the post is straight up and down. A post level can be used for simplicity or a longer level may be used on both sides as an alternative. In this case, a post level was used.                             

The post can now be marked on the bottom of the straight edge. This mark identifies the bottom of the beam material and where the beam will sit on the post. The cut of the post will be determined by the type of beam used. For more information on types of beams, see Chapter 2.

Hold the post against the straight edge material and mark the bottom of the straight edge. This mark is the bottom of the beam. 


Tools

Bar Clamps

Circular Saw

Digger Tamper Bar

Drill

Drill Bit Extension

Drill Bits

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Materials

3" Exterior-Grade Wood Screws

Exterior Rated Simpson Strong Tie SD Connector Screws

Gravel

1/2" x 7" Hot-Dipped Galvanized Bolts with Washers and Nuts

Simpson Strong Tie SD Connector Screws

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