Carl Brahe
I inspected a 5-year -old builder’s home last week. The builder built it, lived there and was selling it. The builder, and his wife, spent a lot of time on the deck he presumably built. The deck was in the process of collapsing. It was separating from the connection at the house. The wooden posts were moving outward and the deck was ready to fall off. Poor construction made this deck a danger to all who walked on it. Every year there are numerous news stories of injuries and deaths from deck collapse.
Every deck made of wood will eventually fail and need to be replaced, but proper construction and maintenance will make them last longer and provide more safe enjoyment. Wooden decks have an average life expectancy of 10-20 years depending on climate and level of maintenance. You can expect about 20 years of useful life in Colorado’s dry climate, if you take care of it.
The most common point of failure for decks is at the connection to the house. Lag bolts should be installed between every other joist, penetrating into the house structure, not just connected to the siding. Most decks that fail are connected to the house by nails, like this one. Poor construction is the number one reason for deck failure.
Inspect your deck a couple times a year. Check the connections at the support posts and the decking. If they are separated like this deck, stay off. This deck is in the process of collapse. With only a little more separating of structure, this deck will fall. Ideally, deck should be constructed with screws and joist hangers to prevent this condition. These nails are being pulled as the deck torques away from the support posts.
This condition may also be found at the stairs. A common construction technique for deck stairs is to simply hang them from a metal strap or two. No vertical bracing is used. The only thing holding these stairs up is a few nails and a thin, perforated steel band. This same technique is often used in building interior stairs, even in high end homes.
Notice how the stairs are pulling away from the decking. You can see the separation at the top edge of the steps as well. Look for this condition in your interior stairs. If you find this separation, don’t use the stairs until they have been repaired, or replaced.
When stairs begin to pull away at the top they can also separate at the bottom.
The second most likely cause of deck failure is wood rot. Reports from people who experience deck collapse from rot say there is no warning. The deck doesn’t creak or moan. It simply collapses. Wood rot is a fungus that eats wood. When the moisture content in wood reaches about 19%, rot begins. It is natures way of recycling dead wood. Treated wood lasts longer, but will eventually rot.
The wood in deck posts should be protected in a few ways. Contact with dirt, or concrete, causes moisture to wick inside posts. The post crumble as you can see in the photos on the left. Concrete footings, of an appropriate size are buried to a proper depth for the locality. Metal brackets are embedded in the concrete that hold the support post just above the concrete.
Improper footing can fails as well. This footing was placed above ground with the post directly embedded in it.Between instability that allows the footing to move around and the freeze/thaw cycle, this deck doesn't stand much of a chance for longevity.
Deck joists rot as well and are often not visible but can usually be felt as a softness, or give in the deck. Note the examples above have no joist hangers.
Inspect your deck at the end of summer and the beginning of spring. Correct defects and perform due maintenance to maximize the life and safety of your deck. Remember to treat the underside of decking when needed. A well maintained deck can last for many years and provide great pleasure, but improperly built, or poorly maintained they can mean injury or death for unsuspecting residents or guests.
Here is an excellent article on inspecting your deck.
Deck Inspections - Part I
By Matthew Steger, ACI, WIN Home Inspection
Many homes have decks attached to them for entertaining and relaxing under the stars, but most homeowners do not perform a regular deck inspection. Each year, people are injured or killed due to faulty construction or the lack of needed regular maintenance of decks.
According to statistics, there are 40 million decks in the U.S. that are over 20 years old. Since the year 2000, the number of injuries and deaths related to deck failures has been increasing according to the North American Deck and Railing Association (NADRA). The typical life expectancy of a wood deck is usually 15-20 years, assuming regular maintenance. Nothing lasts forever, and any wooden structure exposed to the elements 24/7 will require regular maintenance and inspection to ensure safe usage and long life.
As part of a home inspection, a deck should be checked for various things, such as structural integrity, railing size and strength, hardware type and condition, and staircase issues.