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Will my deck support my hot tub

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Jul 24, 2013, 02:00 AM
Will my deck support my hot tub
Hi all - new member here. I've tried searching for existing discussions related to my question but I havent seen anyone mention similar existing conditions such as mine considering that I built a section of my deck that exceeded local code.

So, I just ordered a hot tub that is approx 6'x6' and I'm curious if I should worry about my deck being able to handle the load. My deck is small - 18x8 and roughly 4' above grade. The deck has 6 footings approx 40" deep. I have double 2x12 girders with 2x8 joists. (I'm not a contractor so my description may be confusing - I apologize in advance). My deck is two sections that are both 9x8. The first section of my deck, where you exit the house, is 12'oc and the furthest section that has the stairs to my backyard is 16"oc. When the deck was built we didn't box out the framing for a hot tube with independent footings/4x4s. I'm planning on sitting the hot tub on the back left corner of my deck, so basically the the back edge of the hot tube will be over the rear girder and 12"oc section of the deck. Its only a small 3 person hot tube that holds approx 250 gallons of water and the tub itself is 300lbs - so approx 2500-2600 with people in the tub. Oh, and the joists are sitting on top of the girders and secured with hurricane clips.

My friend who helped me build the deck swears that the 2x12 girders and 12" oc joists will provide enough support and I dont need to worry that we didnt add additional footings for the 6x6 area of the hot tub. Is this true - will the hot tub be well supported?

Thanks in advance for any helpful responses.

Jul 24, 2013, 08:43 AM
You will need more support - ideally a minimum of four posts located underneath each corner of the tub going to solid footers. Since you are going into an existing corner of the deck you'll only need to add three.

Doing the math from what information you have given (rounding out) puts the tub at 3,000 # if filled with water and three people. If the tub is a 6x6, then it will sit on 36SF of deck area. With that weight, you are looking at a live load of 80# per SF. Standard home construction assumes a live load of 40# per SF and decks are generally constructed lighter than that. While the deck you have may seem strong, over time the constant weight of the tub will warp your framing.

Add in 6x6 posts on 2' x 2' x8" footers under each corner and it will support it fine.

This message has been edited. Last edited by: Jaybee,