how to calculate deck load

Deck building is a great way to add value to your home, enhance outdoor living space, and provide a perfect platform for family gatherings and outdoor events. However, building a deck is not just about nailing boards together. It’s essential to calculate the deck load to ensure that the structure can support anticipated loads safely and efficiently. This article will guide you through the process of calculating deck load and give you the confidence needed to build your dream deck without any worry.

What is Deck Load?

Deck load refers to the amount of weight that the deck can support based on its size, material, and structural design. It is a crucial consideration when building decks because overloading can lead to structural failure, posing a risk to your family's safety. The deck load comprises two types of loads, namely, live load and dead load. Live load refers to the weight of items that move on and off the deck, such as people, furniture, and appliances, while dead load refers to the weight of the deck itself, including beams, joists, and decking materials.

Calculating Live Load

Live load is usually the design load for a deck, and it varies depending on the intended use. For instance, a party deck accommodating a large crowd requires a higher live load than a private balcony. The International Residential Code (IRC) stipulates that decks have a live load of 40 pounds per square foot (psf). You can calculate the live load for your deck by determining the occupancy load, which is the number of people you expect to use the deck at once, and multiplying it by 40 psf.

Calculating Dead Load

The dead load is the weight of all the materials that make up the deck, including the framing, posts, beams, joists, decking material, and anything else that doesn't move. To calculate the dead load, you need to know the weight of each material and the dimensions of the deck. You can obtain this information from the manufacturer's specifications or use a calculator, which is available online. Add up all the weights of the materials and divide by the deck's square footage to obtain the dead load per square foot. Dead loads usually range between 10-15 psf.

Combined Load

The combined load is the sum of live load and dead load and is used to determine the design capacity of the deck's components. IRC recommends a minimum design load of 50 psf for decks, which means that the deck should withstand a load of 50 pounds per square foot without failure. To calculate the combined load, add the dead load per square foot to the live load per square foot. For example, if the dead load is 12 psf, and the live load is 40 psf, then the combined load is 52 psf, which satisfies IRC's minimum requirement.

Conclusion

Calculating deck load is a critical component of deck building that requires careful consideration. A well-designed deck should withstand anticipated loads without experiencing structural failure or compromising safety. Knowing the live load, dead load, and combined load helps in determining the appropriate size and spacing of deck framing components, so they don't exceed their load capacities. It's always advisable to consult with a professional deck builder or a structural engineer for guidance in determining the appropriate loads and design specifications for your particular deck.