Roberts Home Inspection Service

Decking Basics / Building Codes

 A  FEW WORDS ABOUT BUILDING CODES.

This information provided here recommends connectors and fasteners for deck construction that may meet the requirements of the 2006 International Building Code® (IBC) and the 2006 International Residential Code® (IRC).

The information contained here provides a partial summary of the requirements of these codes as they pertain to the connections highlighted in this guide. The building codes contain other requirements regarding aspects of deck construction that are not addressed here, check the codes for details.

Please check with your local building department to verify what building codes have been adopted in your area.

Millions of decks are built and replaced each year in the United States and Canada. While decks are a popular feature of many homes, the construction and safety of decks have become a real concern within the building industry. Improper deck building has resulted in a growing number of deck failures and related injuries and deaths.

According to leading experts, the deck is the most dangerous part of the house. Safety Reports state “Decks" cause more injuries and loss of life than any other part of the home structure. Except for hurricanes and tornadoes, more injuries may be connected to deck failures than all other wood building components and loading cases combined.

While decks are required to meet certain code standards and load capacities, it’s estimated that only half of existing decks are code compliant – leaving the other half to be rebuilt or retrofitted.

To help design and building professionals build codecompliant, safe decks, a well known and reputable company - Simpson Strong-Tie® has created a Deck Framing Connection Guide. This guide focuses on the critical connections involved in deck construction and what the code requires for these areas. It is intended to help designers, contractors, inspectors and do-it-yourselfers ensure that their decks are properly constructed per the International Building Code® (IBC) and International Residential Code® (IRC).

The guide includes a complete deck connector system that covers all the hardware needs for deck construction and references the code to ensure it meets current requirements.

DO I NEED TO RETROFIT ? 

5 THINGS TO LOOK FOR ON AN EXISTING DECK.

At the point where the joist bears on top of a beam, there must be a connection to resist lateral and uplift forces. Blocking or framing is also required to prevent overturning of the joists.

Code Requirements

Where posts and beam or
girder construction is used to
support floor framing, positive connections shall be provided to ensure against uplift and lateral displacement.

IRC 2006, Section R502.9

IBC 2006, Section 2304.9.7
 

Joists must be supported
laterally at the ends by solid
blocking or attachment to
a full depth header, band or
rim joist (IRC & IBC). Lateral
restraint must be provided at each support (IRC only).

IRC 2006 Section R502.7

IBC 2006 Section 2308.8.2

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RAILING POST TO DECK FRAMING

The railing connection is one of the more crucial connections pertaining to safety, and
it is often inadequately constructed. In order to provide the required load resistance
at the hand rail, the post must not only be fastened to the rim joist, but also tied
back into the joist framing. Machine bolts through the post and rim joist alone do not
typically meet the performance requirements of the code. The details shown below
have been shown through testing to resist the forces called out by the codes.

Code Requirements

When required:

Guards shall be located along open-sided walking surfaces, porches, balconies or raised floor surfaces more than 30" above the floor or grade below.
IRC 2006, Section R312.1
IBC 2006, Section 1013.1

Height

Guards shall be a minimum of 36" tall (IRC) or 42" tall (IBC).
IRC 2006, Section R312.1
IBC 2006, Section 1013.2

Load Resistance

Handrail assemblies and
guards shall be able to resist a single concentrated load
of 200 pounds, applied in any direction at any point along the top (IRC & IBC), and have attachment devices and supporting structure to transfer this loading to appropriate structural elements of the building (IBC only).

IRC 2006, Table R301.5

IBC 2006, Section 1607.7.1

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DO DECKS REALLY NEED TO MEET CODE REQUIREMENTS ?

Because they look relatively simple to build, many people do not realize that decks are structures that need to be designed to adequately resist certain stresses. Like a house, or any other building, a deck must be designed to support the weight of people and objects placed on them, as well as lateral and uplift loads that can act on the deck as a result of wind or seismic  activity.

The 2006 versions of both the IBC and IRC contain language outlining the general design requirements of structures. This excerpt from the IRC represents a summary of the intent of both codes:

“The construction of buildings and structures in accordance with the provisions of this code shall result in a system that provides a complete load path that meets all requirements for the transfer of all loads from their point of origin through the load-resisting elements to the foundation.”

The concept of a complete or continuous load path refers to a series of solid connections within the structure of a deck that transfer load through its frame to the ground or adjacent, supporting structure (commonly a building). This same principle is applied to the design of all types of wood frame buildings. This continuous load path is created by using a system of structural connectors and fasteners to connect the wood members together.

Listed below are the Most Crucial Connections on any Decking System.

Railing Post to Deck Framing / Stair Tread to Stringer / Stair Stringer to Deck / Post Bases / Joist to Base / Footings / Beam to Post / Joist to Ledger / Ledger Attachment

THE LIFE EXPECTANCY OF DECKS.

Most experts agree that the average life expectancy of a deck is 10 to 15 years. Since deck building started about 30 years ago, there are many existing decks that are past their useful life.

Deck maintenance is often overlooked as well. Decks are exposed to the elements, which can cause damage. It’s important that decks are properly inspected and maintained on a routine basis.

If unsure, it's best to consult with a professional, such as a structural engineer or contractor, to make sure the deck is safe.

FOOTINGS

Code Requirements

Footings

The building codes include specific requirements regarding footing size that are dependent upon factors such as the dead and live loads the deck is

designed to resist as well as soil conditions. Footing should be designed per IRC 2006,

Section R403 or IBC 2006, Section 1805.

Minimum Footing Depths By Code Footings shall be at least 12" below the undisturbed ground surface.

IRC 2006, Section R403.1.4

IBC 2006, Section 1805.2  

Footings shall be designed so that the allowable bearing capacity of the soil is

not exceeded. The minimum width of footings shall be 12 inches.

IRC 2006, Section R403.1.1

IBC 2006, Section 1805.4.1

Note: In order to achieve published load values, footings must provide sufficient concrete cover of the embedded portion of Simpson castin-place post and column bases. In some cases a footing larger than the minimum required by the building codes will be necessary to meet these requirements. See Simpson’s Wood Construction Connectors catalog for more information.

BEAM-TO-POST CONNECTIONS

At the point where a beam meets a post, it must be properly connected to the post in order to resist gravity, lateral and uplift loads. This pertains to solid sawn beams or those comprised of multiple members, whether they rest on top or are fastened to the side of the post.

Code Requirements

Where posts and beam or girder

construction is used to support floor framing, positive connections shall be provided to ensure against uplift and lateral displacement.

IRC 2006, Section R502.9

IBC 2006, Section 2304.9.7

JOISTS TERMINATING INTO BEAM / LEDGER

When joists terminate into a beam or ledger, a connection is required to provide bearing. In cantilever applications the connection must also resist uplift.

Code Requirements

Bearing

The ends of each joist, beam or girder shall have at least 1½" of bearing on ood or metal except where supported on a 1" x 4" ribbon strip nailed to adjacent studs.

IRC 2006, Section R502.6
IBC 2006, Section 2308.8.1

Joists framing into the side of a wood beam shall be supported by approved framing anchors or on ledger strips not smaller than 2" x 2"

IRC 2006, Section 502.6.2
IBC 2006, Section 2308.8.2

Cantilevered Applications

Decks with cantilevered framing members, connections to exterior walls or other framing members shall be designed and constructed to resist uplift resulting from the full live load acting on the cantilevered portion of the deck.

IRC 2006, Section 502.2.2

IBC 2006, Section 1604.8.3