Free Standing Deck Using Two Sets of Posts
When we planned the construction of our deck, we wrestled with whether to install only one set of posts 12 feet out from the house, or to install two sets, with the second set of posts closer to the house (2 feet out) for added support. After weighing the alternatives, we decided it made a lot of sense to install two posts, creating essentially a free standing deck. Here’s why:
Advantages of Free Standing Construction
- The deck can support substantially more weight than if the joists were attached to joist hangers alone. If significant extra weight were added (e.g., a hot tub, which we’ve considered), we would need to double or triple the joists in that area of the deck, but the deck would be able to support the weight.
- If the deck is not connected directly to the house, leaks cannot develop in the house. (Note: Our deck is still connected; see the third drawback for more info).
- The extra set of posts allowed our builder to use a smaller joist size since the spanning distance was not as long. While the cost didn’t completely make up for the labor and materials associated with the additional posts, it made the difference less.
Drawbacks
- Additional cost associated with digging, pouring footers, and the pressure treated 6×6s and 2×12s for the posts and supporting frame.
- Furniture placement under the deck is further limited if you plan to install a patio area or lower deck. We currently have no plans for this.
- If the deck is ultimatley not connected to the house via a ledger board, diagonal supports must be added to handle racking forces (e.g. horizontal forces present on the deck due to a large group of people moving around). We still connected the deck to the house.
Since we planned to build the deck structure to last for years to come, we decided the advantages more than outweighed the extra cost, especially since we may install a hot tub sometime in the future.
What do you think? Did you make a decision on free standing deck construction? What did you choose?
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4 Responses to Free Standing Deck Using Two Sets of Posts
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February 26th, 2009 10:58 am
That’s a great looking deck. My rule of thumb is always the same: more is better. I just over-built a set of stairs for our back porch. The durability and stability, for me, greatly outweigh the slightly higher cost and the extra time.
February 26th, 2009 12:04 pm
You did a great job on the deck. You’ve built it to last and that’s the important thing. Using two sets of posts was the wise decision.
February 26th, 2009 1:43 pm
Properly installed joist hangers are actually stronger than the joists they support. However, reducing the span from 12′ to 10′ as shown here actually increases the strength of the joists by 44% which is a substantial increase in capacity.
Great looking Deck Fred!
February 26th, 2009 9:25 pm
Todd, great additional point. Makes sense to me that joist hangers should exceed the joist’s weight bearing capacity when installed properly.