HOW-TO GUIDES

How to Build and Frame a Multi-Level Deck

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Explore instructions for building and framing a multi-level deck, from tips on freestanding vs connected styles to how to build your transition box steps.

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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For any home project, be certain to follow local code and permitting requirements.

© 2022 Trex Company, Inc.

01. Intro 00:00

02. Determine Functional Areas of the Deck 00:23

03. Framing Considerations 01:35

04. Installing Joists 03:25

05. Transition Box Step 03:48

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Step-by-Step Instructions

01: Planning Multi-Level Deck
02: Transition Box Installation

Chapter 01: Planning Multi-Level Deck

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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.

There are many reasons to build a multi-level deck. Different levels can help separate the deck for unique use cases such as entertainment, cooking, and smaller group sitting areas. Multi-level decks can also follow a slope of the yard by tiering up or down as the ground level does. In this guide, we will walk you through the additional steps required to frame a multi-level deck. For a refresher on the deck framing basics, check out our guides on Deck Framing Layout, How to Install Deck Frame Beams and Posts, How to Install Deck Ledger Board and Attach Flashing, and How to Install Deck Joists.

Step 1: Decide if you are using a freestanding or connected deck framing approach.

The framing of each individual deck can be free-standing, or they can be connected. A freestanding deck means that the deck stands alone and is not attached to the other levels. The different levels could be built as separate decks and finished one at a time. Connecting the decks is having the framing from each level attached to the next level. With the connected approach, the finished product would be completed after the framing was done for all levels. Before starting your multi-level deck project, consult your local municipality to determine which connection type is right for your build.

Step 2: Decide if you want to build each level with a flush beam or a drop beam.

The different levels can be built with a flush beam or a drop beam. The design of the deck will determine if you should use a drop beam or a flush beam. A drop beam can give more design flexibility if there is enough room to fit the beam between the deck frame and the ground. A drop beam would be attached under the joists. A flush beam is used when the deck is very close to the ground. A flush beam will have the top of the joists flush with the top of the beam. An angle bracket can be attached to the top of the joist and hanging slightly over the edge of the joist.

A small scrap of wood can also be used if an extra angle bracket is not available.

These tabs will allow the joist to sit in between and stay flush with the top of the beams while installing the joist hangers.

Step 3: Build out your deck framing for each level

Once you have made your deck framing and beam installation decisions, build out the rest of your framing as you would for any single level deck using the instructions outlined in our guides: Deck Framing Layout, How to Install Deck Frame Beams and Posts, How to Install Deck Ledger Board and Attach Flashing, and How to Install Deck Joists.

Step 1: Determine if you need to add a transition box between your deck levels.

When the height between the two deck level frames is too high to only have one step down to the next deck, a transition box step can reduce that distance and keep the step heights within code. The box step can be used when there are two rises, one from the upper deck to the box and then a step from the box to the lower deck. If the height is more than two rises then multiple box steps or stair stringers will need to be used. For a refresher on how to calculate the rise for your stairs, check out our stair installation instructions.

Pro Tip

If multiple decks are planned with multiple heights, try to make all of the steps the same height or at least close to the same height. This will give consistency through the decks so one does not feel different than the others. In some instances, the step from one deck to the other will not be over the maximum stair height and will not need a box step.

Step 2: Determine if you will install your transition box before or after the decking installation.

A framed box step can be installed before or after the decking has been installed. If you opt to install your framed box step before the decking, proper blocking will need to be installed where all deck ends will be meeting the box step. Proper blocking will need to be installed to support the box step on top of the frame. If installing the box step after the decking, the blocking for the decking ends will not be needed. However, support blocking will be required. In this case, the decking was installed, and then the box step was placed on top of it.

Step 3: Attach the Transition Box

Small details will need to be decided when attaching the box step. The first decision will be where the step is located near the end of the deck. The step could go flush with the end of the deck frame. This would require the fascia to be flush with the outside of the deck. The lines of the fascia would still show. In this situation, the box step was held back the width of the fascia so that it became its own box and not part of the upper deck frame.

Verify that the box step splits the distance between the top deck and bottom deck evenly. Code in this area states that steps cannot vary more than ¼” between each step. Code also states that the step cannot be less than 4” in height. Splitting the difference between the top and bottom deck evenly will ensure that there is little to no variance and keeps the step within code. Be sure to check with your local municipality code to ensure your box steps meet code before construction.

Attach the box step to the upper frame with 3” SDWS Framing screws from Simpson Strong Tie. Make sure to be high enough on the box step so that the framing screw goes into the upper deck framing. Predrill if closer to the edge. Place a framing screw on each end and one in the middle.

Attach Simpson Strong Tie L70Z brackets to the front rim of the box step and down to the deck below with Simpson Strong Tie SD Connector screws. The bracket should be on top of the support blocking that is below the decking and the box step. Place the L70Z’s on each end and one in the middle. This will keep the box step from moving around or raising up.

Once all of the necessary transition boxes are attached, your multi-level framing is complete.

Tools

Drill

Measuring Tape

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Materials

3" SDWS Simpson Strong Tie Framing Screws

Simpson Strong Tie L70Z Brackets

Simpson Strong Tie SD Connector Screws

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