Is Your Deck SAFE?

Photo source: Simpson Strongtie

Building A Safe Deck:

It’s important to make sure your deck is built right and safe!

Most experts agree that the average life expectancy of a wood deck is 10 to 15 years but we all know many decks that are still standing and alot older than that.

It is estimated that there are millions of decks in the U.S. that are beyond their useful life and may be unsafe. Deck collapses have increased in recent years.

Between 2000 and 2008, there were at least 30 deaths reported as a direct result of deck collapses, and more than 75 percent of people on a deck when it collapses are injured or killed. [source: Universal Forest Products]

If you’re building a safe deck or have an existing deck, you should know how to evaluate its construction to make sure it’s structurally sound and safe. Using the proper building techniques, materials, structural connectors and fasteners as well as regular maintenance are key to a safe and strong deck.

Here’s a few tips for you to use to check and see if your deck or porch is up today’s safety standards.

1. Inadequate footing and post connection:

Deck posts that have direct contact with concrete footings end up rotting sooner than posts that are sitting on and attached to a post base standoff.

The standoff is a galvanized bracket that is designed to keep the post a few inches off the ground and the post end grain dry. It also mechanically secures the post to the concrete footing.

Typically when a footing is poured a “J” bolt is embedded into the footing and is used to anchor the standoff anchor to the footing.

If you’re retro fitting a post and the footing does not have a bolt you can always drill a hole into the concrete footing and insert a wedge anchor and then install the stand off bracket.

2. Rotted Posts:

As posts rot they lose structural strength. This may result in the deck to settle, sink or fail.

The simplest way to replace a deck post is to support the deck and use a hydraulic jack to raise / level the deck and also to support it while removing and replacing the post.

Photo: Monument Hall, Concord, MA photo by concord carpenter

3. Weak post to deck connections:

Post to deck connections should be fastened with ½” galvanized carriage bolts. The best connection is one that allows the post to sit directly beneath the deck beam or double or triple rime joist.

Photo: Guard rail bracket. Photo by concord carpenter

Special galvanized connections make attaching the post in this situation a breeze.

Photo: Monument Hall, Concord, MA photo by concord carpenter

4. Wobbly deck:Tall decks sometimes have a bit of sway or wobble. Address this by adding 45 degree diagonal supports to the support posts and rim joist.

Another method is to add a diagonal brace, corner to corner, under the deck. Fasten this brace to every joist with two nails.

5. Inadequate ledger to house connections:The ledger is responsible for ½ of the decks weight and nails alone are not strong enough to hold a deck onto a house.

For a strong connection install ½” galvanized lag bolts, or if you have access to the inside fasten lag bolts with washers and bolts. Fasten the ledger board every 16” and offset the lags. Install the lag or thru bolts tight and do not counter sink them.

6. Missing or wrong joist hanger nails:

Many carpenters and “do it yourself deck builders” often do not install nails into all of the joist hanger nail holes or use the wrong nails entirely.

For the ledger board hangers I use3 ½” hot dipped galvanized nails to secure a hanger to a wall ledger. This gives you added strength. The long nails bite into the framing members behind the ledger for maximum holding power.

I use the 1-1/2 in. joist hanger nails for nailing into the side of the joist. For double hangers or for fastening hangers to the outside double rim joist, I use 8d or 10d nails.

all exterior nails should be galvanized or stainless steel. Anything else will rust and fail over time.

7. Missing or worn out ledger flashing:The ledger is the board fastened to the house and is responsible for supporting ½ of the decks weight. Because it is attached to the house it is important to keep water from getting behind it and into the house.

To replace the flashing the deck board closest to the house and a layer or two of the house siding need to be removed. Aluminum, galvanized, vinyl or copper flashing can be used. I always “pre-flash” this area with a thin layer of rubber flashing and then apply the metal flashing.

This rubber acts as a secondary flashing in case water sneaks past the metal. It also seals around any nails that might be put into the ledger.

8. Loose railings:

Clearly a safety hazard on taller decks, most loose railings are due the railing post fasteners loosening over time.

It’s always advisable to install your posts inside the rim joist so you can install pressure treated blocking on all sides of the post to ensure that the post stays tight. Never rely on nails alone to make a railing post secure. Simpson makes a special galvanized bracket to secure rail posts.

Deck Safety Retrofit:

If your concerned about your deck not being up to code consider adding structural connectors to bring it up to code.  Read this article on Deck Safety Retrofit for ideas on how to retrofit an existing deck and also to learn about the latest IRC 2012 deck code requirements.

 

Stay safe ~ concord carpenter

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