Will the deck hold up?

[KarlXII]

I'd like to place the tub on the deck outside the house.
Since the tub is quite heavy, the question is: Is it strong enough?

Construction is as follows: (Sorry if I don't use the proper terminology   )

Concrete plinths appx. every 2,5 yards along 2x8" beams.
The bottom beams are appx 2,5 yards apart.
On top of that, 2x6" floorbeams  24 inches apart.
Last is the deck floor boards, 4,8 inches wide and just over an inch thick. (28mm, an inch is appx. 25 mm.)

[Tatooed_Lady]

can you have an inspector come out and check? The larger Hot Spring tubs (Vista and Grandee, 500 gallons of water and 6-7 people) require a deck that can support 115 pounds per square foot of "dead" or "filled" weight, which includes occupants that weigh 175 pounds, each. The smallest HS tub (Jetsetter) still requires a deck that can support a minimum of 90 pounds per square foot....I guess I'd recommend the same thing to you that's been said to me:
Ask a pro if your deck will support the weight....
Even if it was made structurally capable, if it's an older deck, there might be issues with rot or breakage now....plus, if you DO put the tub on it, will there be enough room to move around the deck?
Whatever you decide, ENJOY!!!

[jim97219]

Here are two links for you to check out.
http://www.whatsthebest-hottub.com/cgi-bin/yabb/YaBB.pl?board=wtb-hottub ;action=display;num=1139356183.  

http://www.whatsthebest-hottub.com/cgi-bin/yabb/YaBB.pl?board=wtb-hottub;action=display;num=1139361997;start=1

My gut feel is that you don't have anywhere near enough support there for that kind of weight.

  365 kilos for the tub empty.
1,525 kilos for 1,525 liters of water
  320 kilos for 4 people @ 80 kilos each.
2,210 kilos total on a 3.2 sq m space is about 700 kilos/sq meter.  Does my math look right?  Do you think your deck will hold that kind of weight?

Please double-check my math; I'm an  American and I don't do much metrically.  But I do know that I'm 185 cm tall, weigh 70 kilos and wear a size 44 shoe.

Bottom line is that Tattooed Lady is right, get someone knowledgeable to check it out before doing anything.

Jim

[KarlXII]

Thanks Jim.

Yep, your math looks right and nope, I don't think it will hold.
That´s why I'm asking. As an amateur, you tend to oversize everything you build so I wouldn't be surprised if it were to hold with a margin.
I just hoped that there was a universal formula out there, specs on a deck that works fine with those loads..

[Tatooed_Lady]

  365 kilos for the tub empty.
1,525 kilos for 1,525 liters of water
   320 kilos for 4 people @ 80 kilos each.
2,210 kilos total on a 3.2 sq m space is about 700 kilos/sq meter.  Does my math look right?  Do you think your deck will hold that kind of weight?

Please double-check my math; I'm an  American and I don't do much metrically.  

first off, I love when people actually agree with me...it makes my crappy childhood seem worth it *wink*
secondly....Jim, you had me fooled...you've got litres, kilos, meters....looks pretty ok to me....but then....I know SQUAT about the metric system other than it makes my head hurt.....  

[jim97219]

Karl,

Here's a link to a forum I follow every so often http://www.handymanwire.com/ubbthreads/ubbthreads.php?Cat=.  I'd suggest you post on the the Handyman section.  One of the moderators is Clint Robbins.  He's an engineer and I'm sure he'll be able to tell you how much more support you'll need.  Others will have good advice as well.

If I may suggest, post in feet, inches and pounds, not metrically and not in yards.  Sorry but we Americans just don't do metrically very well at all.  And convention here is to use fractions, not decimals.  By the way, how do you guys measure lumber?  Over here, what we call a 2x4 doesn't measure 2" x 4" but 1-1/2" x 3-1/2".  That will make a difference in the load calculations.

Not a problem, Tattooed Lady.  I kind of got used to the metric system in my Peace Corps days in Costa Rica.  Nowadays, I kind of dabble in it, selling metric taps, dies, drill bits and the like.

Jim

[Tatooed_Lady]

who the h@!! decided to make 2x4 = 1 1/2x3 1/2???
They oughta be in the lineup with the idiots that invented Legos and shag carpeting (BAD BAD BAD combination, ask most any parent) and shot...

[KarlXII]

Karl,

Here's a link to a forum I follow every so often http://www.handymanwire.com/ubbthreads/ubbthreads.php?Cat=.  I'd suggest you post on the the Handyman section.  One of the moderators is Clint Robbins.  He's an engineer and I'm sure he'll be able to tell you how much more support you'll need.  Others will have good advice as well.

If I may suggest, post in feet, inches and pounds, not metrically and not in yards.  Sorry but we Americans just don't do metrically very well at all.  And convention here is to use fractions, not decimals.  By the way, how do you guys measure lumber?  Over here, what we call a 2x4 doesn't measure 2" x 4" but 1-1/2" x 3-1/2".  That will make a difference in the load calculations.

Not a problem, Tattooed Lady.  I kind of got used to the metric system in my Peace Corps days in Costa Rica.  Nowadays, I kind of dabble in it, selling metric taps, dies, drill bits and the like.

Jim

Thanks.

No, I know you guys don't use metrics - thats why I tried to post in inches and yards. Unfortunately I thought yards was common use - but I guess that's the Limeys. As we all knows they're half-way between.
Next time I'll use feet.

[Tman122]

I'd like to place the tub on the deck outside the house.
Since the tub is quite heavy, the question is: Is it strong enough?
Construction is as follows: (Sorry if I don't use the proper terminology   )
Concrete plinths appx. every 2,5 yards along 2x8" beams.
The bottom beams are appx 2,5 yards apart.
On top of that, 2x6" floorbeams  24 inches apart.
Last is the deck floor boards, 4,8 inches wide and just over an inch thick. (28mm, an inch is appx. 25 mm.)

I'll try and decifer and then answer.

OK beams held up by post on concrete cool about 7-8 feet apart but no size on the posts and on the beam, is it a single beam or doubled up? Is the beam sitting on top of the posts or just screwed to the post or bolted to the post or a combination of any of these? 2x6 joists is not suffiecient unless your center to center is less than 12 inches The decking will be fine if it's supported properly. 2 sets of post's and beams under the tub with 2x8 on 16 inch centers (or 2x6 on 12 inch centers) And I would prefer 4x6 posts with 2x10 beams notched into the posts. But I believe 4x4 post and 2x8's header is suffiecient. Check your local codes.

[KarlXII]

Pictures speaks louder than words .
This is how it looks today, from west:

Single beam, concrete thingy appx 8 inches wide.
On the right side, note that the beam does not sit on the concrete thing, its screwed into the 4x4 post.

From the North:


I guess it really does reinforcement - but how?  
I'm planning to let the center of the tub sit right on top of the 2x8 beam.

[Tman122]

Put another beam just like that one for the other side of the tub. Double up the 2x6 joists between the 2 beams under where the tub is going to be.

And I am a little concerned about that 90 inch span between posts on a single header. I'd like to see another post in there, or a double 2x8. And are those concrete footings or just blocks?

[KarlXII]

Put another beam just like that one for the other side of the tub. Double up the 2x6 joists between the 2 beams under where the tub is going to be.

And I am a little concerned about that 90 inch span between posts on a single header. I'd like to see another post in there, or a double 2x8. And are those concrete footings or just blocks?

Sounds good...
But it sure is bothersome work to unscrew those floorboards. I dont think it´s possible to get the extra 2x6:s in place without doing it.
That's concrete footings. They go 3 feet into the ground.

Thanks for your help.

[hotelier]

I am no expert but your 2x8 beams look woefully inadequate.  You can do a search on the internet looking for " span tables" that will provide some information regarding how much weight beams and joists will hold.  

I have double 2x10's as beams, 8' on center and it is just passable for the weight of a hot tub.

[Tman122]

Thats why I said there should be 3 post's under each beam and it should be double 2x8. Yes alot of work but beats picking a crushed tub out from under a broke deck.

With an extra post it would be aprox. a 40 inch span on a single 2x8, a span load table can tell you how much weight this can handle. 2- 2x8 may be required.

[KarlXII]

I'm backing out of the reinforcement idea altogether.

I'll build a new section of the deck, with proper dimensions as above. That way I also can lower it down so we won't need the stairs to enter.
Looks kinda cool too, with the tub halfway down into the deck.