Did you know that before the 1970s decks were typically used solely for outdoor grilling; there was no space for other activities. In recent times, however, deck size and usage has continued to grow. As deck use expanded, so did deck designs. Designs for outdoor kitchens, dining and living areas, and more are now commonplace
Perhaps because of their simple past, decks today are often constructed without following codes or material guidelines – resulting in issues ranging from minor to life-threatening.
According to the Consumer Product Safety Commission (CPSC), an average of 6,000 people per year are injured due to structural failure or collapse of a deck, porch, railing, or staircase.
When decks are not constructed according to code, accidents and loss of investment can occur. If you are spending more and more time on your deck, because of the current COVID climate, you may want to have it inspected for safety.
Our engineers have been asked to assist with a multitude of problems resulting from improper additions of decks. Here are a few of the problems our engineers have been seeing and you can look for:
One of the most common problems with decks is the improper installation of a ledger board. Ledger boards are commonly expected to carry 400 lbs per linear foot, but many decks have been improperly connected to the house itself; resulting in damage to the home as well as safety concerns.
For example, if a home has siding, the siding must be removed and flashed during the construction process. Flashing is the process of adding a strip of water-resistant material against the home to keep moisture from the structural support elements.
In the picture above, the deck’s ledger board was attached to the house through the brick veneer, which is not intended to carry a load. In this situation, the improper addition has caused rotting and caused the deck to pull away from the house.
Deck posts are sometimes inadequately attached to their foundations. The load transfer between posts and foundations is an important element and a single source for deck failure. We often encounter incorrectly sized post footings. In the footing world, once size does not fit all, mostly due to soil strengths variability. Determining the footing size is based on the total post load and the soil type.
Wooden framing elements, such as posts and bracing, that are attached to the foundation, must be at least six inches above the soil, per code, because the framing elements can rot. The bracing elements in the photo below had completely rotted and pulled apart at their connections because the foundation connection is below soil grade.
Handrails and Guardrails:
Handrail and guardrail connections are another common area of failure. Typically required to resist more than two thousand pounds of force for each support post. These requirements are specifically outlined in the Residential Code; with definitive height and width requirements. Our engineers have seen numerous handrails that are improperly attached to the deck, which can be the sole cause of injury.
We frequently see guardrail connections like the image above. This deck is approximately 30” off the ground with shaky guardrails. This is mainly due to the attachment of the rail post directly to the surface of the deck as seen. This is unsafe, as well as unattractive. A safer way to construct guardrails is attaching them to the framing of the deck.
A stair stringer, or stringer board, is a set of boards that support steps. Each stairway is typically required to support thousands of pounds – an amount equivalent to driving your vehicle up the stairway. The stair stringer must be accurately measured in many different ways; the depth, the riser height, and maximum variance are all integral parts of the safety of the stairs. Very frequently they are not to code and do not have the capability of supporting the required loads.
Below is an example of a deck that was over spanned and not appropriately supported. These will be demolished and relocated to a different section of the deck.
Whether you have concerns about your deck or you want to replace your deck, Level Engineering is here to aid you in inspections, evaluations, and, if appropriate, the design process. We are happy to help.
Give us a call at (720) 408-0119 and our client relations team will assist you in scheduling an appointment with one of our engineers.