Deck support for spa tub

[Randy L. Mayo, PE]

Bob

Any loading, span lengths, lumber sizing and connection details not prescribed in the code books will require an engineer for design calculations and details as spelled out in IRC 301.1. The entire deck can be designed with the code books using the standard 40 psf live load and 10 psf dead load except for the area supporting the tub. Water weights 62.4 lbs per cubic foot so 30 inches of water depth will result in 156 psf plus the weight of the tub and deck framework could approach 200 psf. The dead load in the tub area is now 20 times that of the rest of the deck. Basic engineering procedures require the actual dead loads to be multiplied by 1.2 and the actual live loads to be multiplied by 1.6 to provide the necessary safety factors.

I have oversimplified the design considerations to make a point, the liability issues with hot tubs and all other design issues that fall outside the code books is too great. I would recommend a structural engineer if they choose otherwise the liability is on them.

[Bob Elliott]

Guess I will disclaimer extra weight calculations from now on

[ROBERT V. YOUNG]

I to will say to recommend a carpenter.
BOB water is 63 pounds per square foot.
A hot tub varies in sizes and normally above 15 SQ. feet.
Now you multiply the gallons by 8.3 if not mistaken and you get a patio that is under rated for that much load.
I see 6/6 that are 2 inches above the ground and surely get wet and wick water when the grass is high.
The center post is a 8/2 and almost off the cement pier or footing.
There is to much going on and I need not see any more photos but to say" recommend a carpenter ".

[ROBERT V. YOUNG]

BOB we all make mistake and you make little.
You are always helpful BOB.
I know you will remember this.