May, 2008
Feature
Inspection News and Views from the American Society of Home Inspectors



Making the Connection: Eight Key Areas for Safe Deck Inspection

JIM MAILEY

Constructing a safe deck requires research, proper hardware, regular maintenance and oftentimes, help from a professional builder or inspector. Many Americans, however, still view adding a deck to their home as a simple, Do-it-Yourself project for Memorial Day weekend. Over the last 10 years, there have been more than 800 reported injuries and 20 deaths as a result of deck collapse.

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The ledger connection, where the deck attaches to the house, is the most common type of deck failure.


Of the 40 million decks in the United States, it’s estimated only half meet building code requirements. To promote deck safety, ASHI is teaming up with the North American Deck and Railing Association (NADRA) and Simpson Strong-Tie to encourage homeowners to make sure their decks are inspected before outdoor barbecues and parties begin. And May — NADRA’s Deck Safety Month® — is a perfect time for a deck inspection.

There are many components to consider when inspecting a client’s deck. Checking for wood rot and large cracks is key, but you also must evaluate the structure as a whole.

To ensure the structural safety of a deck, it should be built with a continuous load path. A continuous load path is a method of construction that creates a series of solid connections within the structure of the deck that transfers the load through its frame to the ground and adjacent support structure, commonly the house.

A continuous load path requires more than a few nails and some deck boards. There are a total of eight key areas of a deck that must be secured with connectors and fasteners to ensure that the structure can support all of the weight that’s placed on it. When inspecting a deck, you’ll want to make sure the following areas of the deck are properly fastened.

CRITICAL DECK CONNECTIONS

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1. Ledger-to-Wall Framing
Correct ledger attachment is critical when a deck is attached to another structure. One of the most common causes for deck failures is ledgers that are not properly secured and pull away from the primary structure, resulting in collapse. The two most common ways to correctly attach the ledger to a structure are lag screws or machine-bolts through the ledger and into the rim joist of the supporting structure.

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

3. Beam-to-Post
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.

4. Joist-to-Beam
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 also is required to prevent overturning of the joists.

5. Railing Post-to-Deck
The railing connection is another important connection pertaining to safety that is often overlooked. In order to provide the required load resistance at the hand rail, the post not only must 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. Instead, a mechanical connector installed into the joist with bolts through the post is needed.

 6 & 7. Stair Tread-to-Stringer and Stair-Stringer-to-Deck
Stair stringers must be properly connected to the deck, and treads properly connected to the stringers, in order to resist loads. In addition, code requirements regarding openings between stair treads and stair railing must also be met.

8. Post-to-Concrete
In order for posts to properly resist various types of loads, they must rest on and be anchored to concrete footings. Patios and pre-cast concrete piers do not qualify as proper footings for deck construction.

Posts must be correctly attached to a concrete footing in order to resist lateral and uplift loads. Unless posts are naturally decay-resistant or made from preservative-treated wood, they must be elevated off the concrete by 1 inch to help prevent decay at the end of the post due to moisture.

CORROSION

Not only should connectors in the critical areas be present and accounted for, they must all be in good condition. The issue of corrosion with metal connectors and fasteners heightened when the industry moved away from CCA to other types of preservative-treated wood. It’s important when inspecting decks made from preservative-treated wood that the proper connectors and fasteners are used. In many cases, Simpson Strong-Tie ZMAX® (G185) and hot dip galvanized (HDG) connectors and fasteners provide adequate corrosion resistance. There are parts of the country that are considered at a higher risk for corrosion, such as areas along the coast, areas exposed to chemicals, industrial zones, etc. In these cases, the use of stainless steel connectors and fasteners is recommended. Stainless steel connectors and fasteners provide the highest level of corrosion resistance. For more information about corrosion and connector coating recommendations, visit www.strongtie.com/corrosion.

Adding the right connectors and fasteners to a deck is an investment of a few hundred dollars that often will prevent a complete rebuild and keep deck owners and their families safe. Always remind your clients to regularly inspect and maintain their decks. If they’re not comfortable doing this themselves, recommend they hire you or another qualified, professional home inspector. If built and maintained properly, a deck will result in years of enjoyable and safe outdoor living.

Simpson Strong-Tie has developed a comprehensive Deck Framing Connection Guide that can help you through the process of making sure a deck is safe, secure and code-compliant. You can download the guide or request a copy at www.strongtie.com/safedeck.