Reinforce Balconies and Decks
05/03/2023
Make Resilient Upgrades | Strengthen Your Home • Earthquakes
Why do they matter?
Balconies and decks are attractive features of a home, but they also add to the weight and earthquake loads during an earthquake.
What do I need to know?
There are three things to focus on when evaluating your balconies or deck’s resistance to earthquakes:
- The effect of additional floor area
- Anchorage for earthquake loads on your home
- Vertical support
Additional floor area
- The addition of a balcony or deck creates additional weight and increases the earthquake load on your home. Consider the added loads if a balcony or deck was not part of your original house design.
- Balconies and decks can concentrate the added earthquake load on one side of the house and one braced wall line. This can contribute to rotational behavior and concentrations of damage.
- Balconies extending more than 6 feet past the exterior house wall typically require engineered design.
- For larger balconies and decks, consider separating the balcony or deck from the home by providing a gap to permit independent movement of the balcony or deck.
Anchorage for earthquake loads on your home
- If your balcony or deck is laterally supported by your house, adequate connection to the house is key to good earthquake performance
- Ensure that your balcony or deck is adequately fastened to the floor sheathing or floor framing, and that there is blocking where the cantilever bears on the exterior wall.
Vertical support
- Vertical load connections and moisture and decay are two important considerations related to the vertical support of decks and balconies.
- A history of deck collapses in the U.S. has proven that inadequate connection between the house and the deck is a serious concern. Make sure that your vertical load connections are sufficient.
Where do I start?
- Visually inspect your balcony or deck to determine its condition. If you are unsure of its condition, consult an engineer to determine its structural stability.
- Ensure all handrails and stairs are structurally strong and in good condition.
- Ongoing maintenance of balconies and decks is important to maintaining their structural integrity.
- Design the joints of exterior decks so that moisture will not collect in the connection area.
- If a new balcony or deck is to be added to the home, consult an engineer to ensure it is earthquake-resistant.
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