How to tell if your deck can carry the tubs weight

[parmstr]

Any suggestions???  We are looking at buying a hot tub, but are unsure if our deck can hold the weight.  We have put in a couple extra supports but we are still a little worried if it will hold the weight, before we purchase one.

[zzaphod42]

If you are really unsure, get a service tech from the dealer to do a site inspection for you. They should be able to help you out, and a lot of places don't charge anything for the service.

Joe

[OnMedic]

Even better yet, contact the city for codes which should include weight guidelines for span, joist spacing and construction material.

[spahappy]

For most spas your deck should be able to hold 90 pounds per square foot. Most older decks will need to be beefed up a bit with a few extra stringers and 4-bys.
Contact a builder or even a good lumber yard.
Spahappy

[Dr. Spa™ Ret.]

There are 3 methods I've found to work quite well.

1. Begin filling the spa. If creaking is heard, QUICK, turn off the water. The deck isn't strong enough.

2. Blow to college educational fund for the kids on yourself. In 4 years you can complete a degree in engineering and make the derermination youself.

3. Pay the couple bucks to a licensed structual engineer to make the determination for you and save the big bucks for the kids.

................ I gotta get a life................

oooooooooooooo almost forgot... A lot of people just beef up the deck so it's strong enough to support a fully load aircraft carrier. The cost of an engineer will frequently save you more than their costs in overkill.

[UnderTheStars]

Hello Parmstr!  It's a great question and not one to "just guess" about.  You can go the engineer or architect route but it's expensive information.

You should start with your local code office.  (If you can't find them, call your city's main info # and ask for the area that issues building permits.)  Spend an hour and go there with some info in hand.  Be ready to tell one of the building inspectors:
  *weight of the tub with water (from manuf. web site) and the weight per square foot if available
  *sketch of the existing deck framing (size of uprights, joists, and decking boards - for example, are the joists 2x6, 2x8?  are they spaced every 16", every 24"?  Just sketch out what you already have.

The code office will show you "span & load tables" - same thing an engineer/architect will work from to determine, "What's the least amount of material that can safely carry the load?"  Also ask the inspectors thoughts on "deflection"  -  they'll explain.

Call before you go - some offices will make an appointment with you, some will tell you the inspectors are available in-office one day a week at a certain time.  Just understand their job is "out of office" - most of the time they are inspecting job sites to ensure builders are following code. . .

The level of help you get will undoubtedly vary from one municiapality to the another.  However, on average these folks are very patient with homeowner's and willing to help you with your question.  Finally, know your limitations!  If you understand everything the inspector talks about you are probably fine to proceed and design/re-inforce your deck.  However, if any of it is confusing to you - hire someone.  Get a builder, or perhaps a larger building co. with and architecht or engineer on staff.   Look, I have two brother-in-laws.  One could design/build the space shuttle.  The other - If you ask him to hand you a phillips screwdriver he will say, "uh, star thing or straight thing?"  . . .both great guys, not both qualified to handle your deck question.  So know your limits and know if you should pay for the right kind of help.

Hey, shop now, design now and plan on being in your tub before the leaves change - get in gear!

[CraigW]

Just to add to the above good info. Make sure you do check with your local govt, especially if you are going to get permits for electrical etc. In my county here in MD, if you are putting a tub on a deck, you are required to have a professional engineer's signature on the deck plans. In other words, you have to pay a structural engineer to do the analysis. For me it was cheaper (and worked out better actually) to pour a concrete slab and build my deck around the tub!

[parmstr]

Thanks for all of the advice.  

[doodoo]

I would not even mess with this. Get yourself an engineer to look at it and tell what you need. That's what they're trained for and know the math a lot better than sticking a couple of 2 bies under the deck for additional support.