Did you know that more decks collapse in the summer than all the other seasons combined? It makes sense because during the summer, decks are used more often than any other season.
Almost all decks that collapse did so while the decks had people using it on top or the deck was under a heavy snow at the time.
This is interesting. There has been no correlation found between a deck failure and whether or not the builder had a building permit. Neither has one been found between decks that were built by a home owner or by a contractor.
Here's a short informative video on a proper deck ledger installation.
More injuries actually occur due to failing of deck railing than the complete collapse of decks.
Deck stairs should have graspable hand rails, a feature that is notorious for not having been added.
Spacing codes for rails tend to be ignored by do it yourself home owners and even building contractors. IRC code prohibits guard rails from having any openings that would allow a 4" sphere to pass through. This is an important safety measure to protect children.
Downspouts should not direct water near deck posts and sprinklers should never be near enough to the deck to get the posts wet, as this leads to faster decay of the wood.
Most of the time when a deck collapses, about 90 percent actually, it is the result of the separation of the deck from the house by the deck ledger board which connects to two. This allows the deck to swing away from the house. Rarely do decks break in the middle. This is likely because of failure to install lag bolts, or failure to intall them properly.
For maximum safety there should be lag bolts holding the deck to the ledger board that run through to the sill. If only nails are used to hold the deck to the home they can slowly work themselves free over time. I found a video on youtube that discusses the lag bolts installation.
The most commonly used way to attach a ledger to a structure correctly are with lag screws or through-bolts. The installation of through-bolts requires access to the back-side of the rim joist which, in some cases, is not possible without significant removal of drywall within the structure.
The best way to avoid moisture damage to a support post is to place the post on top of a concrete pier or column so that the post is not in contract with the soil. It should be bolted on top of the concrete pier. Contact with the soil means greater chance of moisture damage. However, the advantage of stability is given to posts that go directly into the ground.
Deck post footings should be installed below the frost line. Without concrete footings for a deck post to rest upon, it's possible that the post could sink farther into the ground. In the buried post footing method the post is placed on a underground concrete pad and concrete is poured around the pressure treated post which is rated for ground contact. The disadvantage to this would be if the post were damaged and needed to be replaced, it would be more difficult to replace.
A deck post buried in the ground touching the soil can rot even when it has been treated. Even posts that have been buried and had concrete poured around can still rot inside the concrete as moisture seeps through. Something to keep in mind is that home inspectors can't see what it looks like under the ground. A post could be rotted under the ground and it would be unseen to the inspector.
Here's a good video I found on youtube that does a great job of describing deck post connections.
by Tim Frady Home Inspector
East Tennessee Quality Home Inspections
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