how to extreme

Building a Code-Compliant Deck

Construction How-To, Decks, Decks, Outdoor Living July 13, 2015 Sonia

If you built your deck smaller than the longest available decking board length, you can install the decking without any joints.

We use our speed squares to space the deck boards from each other during installation. This provides even, consistent and professional looking deck-board spacing.

When we get to the last few deck boards next to the house, we measure and to determine the width of the very last board. In a perfect world a full-width board would drop into place, and the deck would be complete. The reality is that the last board usually gets ripped to size, and we hate installing a 1- to 2-in. ripped board. To avoid this, we rip the final three or four boards down 3/4 to an inch and install them. This method gives the appearance of all full boards at the house.

After the decking is complete, it’s time to reinstall the siding. Some carpenters will put trim on the deck and side to that trim, or simply keep the siding off the decking 1/2 to 1 inch.

Now is the time to clean up your tools and celebrate. You’ve just built your first deck and you might as well start enjoying it.

Railing Systems

For decks more than 30 inches off the ground, railings are critical safety features. The posts should be a minimum 4×4 size and be solidly anchored to the deck joist and rim joist of the structure. Use two through-bolts and a metal tension tie for the upper bolt connection.

If a deck’s guard-posts anchoring does not have a minimum allowable tension load of 1,800 lbs. for a 36-in. maximum railing height, they should be replaced. They can be retrofitted with a tension tie, through-bolts and or blocking as needed. Follow IRC code requirements when installing fasteners into guard posts.

Guard rails can be either 36 to 42 inches high (refer to your local code for guidance). Balusters in the railing system should also be installed so a 4-in. sphere can not pass between them.


Stairs, stair stringers and stair guards must meet the IRC design and strength requirements for tread height and opening/spacing requirements. The steps you should have a consistent tread depth with a 7-3/4-in. maximum riser height. A 3/8-in. deviation from one another is allowed by code but should be avoided.

If the stairs have an open riser they should not allow a 4-in. diameter sphere to pass through. Like the maximum spacing for balusters, this is intended to prevent small children from getting stuck or falling through.

Additional metal connectors can be used to connect stair stringers to the deck frame.

Editor’s Note: Robert Robillard is a remodeling contractor based in Concord, MA. He is also the editor of a

Side Note 1

Easy Code-Compliant Solution for Attaching Decks to Homes

DTT1Z_installSimpson Strong-Tie introduces a new deck tension tie for attaching a deck to a home that meets newly updated code standards. The DTT1Z deck tension tie is a safe and time-saving alternative that eliminates the need to access floor joists from inside the house. Instead, it is fastened from outside the house. The DTT1Z addresses a new 2015 International Residential Code provision (section R507.2.4) that allows four 750-lb. lateral connectors to be fastened to structural framing joists members in the house. This provision is an alternative to using two 1,500-lb. lateral connections from the deck to the floor joists within the house.

The DTT1Z fastens to the narrow or wide face of a single 2x with Strong-Drive SD Connector screws. The new Strong-Drive SDWH Timber-Hex HDG screw with an integral washer attaches the tension tie to the supporting structure with a minimum of 3 inches of penetration. Learn more at

Side Note 2

Reimagine Outdoor Spaces with the 3D iPad App from AZEK

AZEK Building Products is making it easier than ever to visualize new deck, railing, paver and trim products on a home. A free new app, the AZEK iPad App, provides the power to reimagine home and outdoor living spaces in realistic 2D and 3D renderings. With the new app, it’s easy to turn dreams of outdoor living spaces into visual reality with a simple tap or swipe using five different product scenarios. From inspired deck and railing designs, trim and molding applications, porch colors and paver layouts, the app places the power of creative outdoor visualization in any user’s hands.

Starting out in the 2D section, an iPad user can choose any of five home scenes, and mix and match products, designs and colors to customize the scenes.  After exploring the two-dimensional visualization and customizing the product color schemes, the user can then take the design to the level of cutting-edge 3D technology to bring an entire house to life.


In the 3D experience, a user will scan what is known as a “visualization marker”, such as the cover of any AZEK catalog or a downloadable image from, to enter the exciting world of Augmented Reality (AR). In the AR experience, a 3D home appears and the user can personalize the house, rotate it 360 degrees, change product colors and then zoom in to make sure it’s perfectly designed. If a visualization marker isn’t available, Virtual Reality (VR) mode can be used to view and customize the AZEK home in 3D.


Once the home has been customized, it will be easy to imagine how a family might enjoy their outdoor spaces. And, after completion, the dream design can be saved, adding notes or tags, and then shared with friends. A user can even invite others to experience it. To learn more about the app, visit