# Hot-tub Frame



## Big Mackey (May 18, 2007)

Hello

I am looking for some advice on a hot-tub frame.

I have a 5 person hot-tub in my house and i want to put it outside.
Supposedly a hot-tub can weigh 3,000-4,000 pounds full of water and people.

I am planning on using pressure treated 2x10s (actual size 1 1/2"x7 1/4") and 2x4s (actual size 1 1/2"x3 1/2")

The hot-tub's top rim will sit on the railing and the bottom of the hot-tub will sit on the floor of the frame

Check out my plans and tell me what you think, the brown vertical studs are the 2x4s the rest is 2x10s.


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## Zel1 (Mar 21, 2007)

Check this site out: http://spaforums.com/index.html

All I remember about this is that the measurement of those 2x4's is extremely critical. Too long and the bottom of the tub will not sit on the base. Too short and the rim will not sit on the top supports, this could lead to cracks when entering or exiting. Good Luck.


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## NateHanson (Apr 15, 2007)

Big Mackey said:


> pressure treated 2x10s (actual size 1 1/2"x7 1/4")


Perhaps I'm misunderstanding you, but 2x10s are not 7 1/4" wide.


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## Big Mackey (May 18, 2007)

Thanks for the link Zel, My plan is to make the 2x4s 1/4" longer than needed, then I will use 1/2" of construction adhesive (liquid nails) and squish the hot-tub into place for a perfect fit, I will be using a sheet of plastic on top of the construction adhesive, so the hot-tub doesn't get glued to the frame.


NateHansen, You are absolutely right:thumbup: 
You see..... I measured the original lumber used to hold the hot-tub and then I looked at this lumber sizes chart http://hometips.com/buy/buildingmaterials/lumber/lumber_sizes.html to design the new frame, lets just say they need to straighten up there act.

If your wondering, why I don't just copy the original frame, I can't because it was using the floor as the bottom support.

My new design will be using 2x10s for the bottom rafters and 2x8s for the top railing.


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## Big Mackey (May 18, 2007)

Hello again

I cut all the 2x10s for the bottom of the frame. My plan was to use 3 1/2" deck screws to screw everything together, probably 4 or 5 in each 2x10s end, But now I'm having second thoughts.

Will a frame using galvanized 2x10 joist brackets be stronger than a screwed together frame?

I also added a extra joist to the bottom of the frame.
http://img.photobucket.com/albums/v738/ARTHUR101/bbbbbbbb.jpg?t=1179719565


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## jproffer (Mar 12, 2005)

Screws are tempting to use for everything, I know, but screws don't have NEAR the shear strength that nails have. You need all the shear strength you can get.

Use 16d nails for thru nailing and whatever nails the hanger manufacturer recommends for the hangers.


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## Big Mackey (May 18, 2007)

jproffer said:


> Screws are tempting to use for everything, I know, but screws don't have NEAR the shear strength that nails have. You need all the shear strength you can get.
> 
> Use 16d nails for thru nailing and whatever nails the hanger manufacturer recommends for the hangers.


Thanks for the info 

I would rather nail it all together, But I'm worried about the nails working loose after 5-10 years of 2,000 pounds of water sloshing back and forth.

Should I use a combination of deck screws and 16d nails?

Or should I buy these GRK R4 http://www.grkfasteners.com/en/R4_1_2_information.htm 4" X #10 Multi-Purpose Screw, They have a average shear of 687 pounds.

Dose anyone know what the shear strength of 16d nails? I am having a hard time finding the info.

Thanks :thumbup:


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## Big Mackey (May 18, 2007)

OK, I bought the 2x10-2x12 joist hangers, But I am not sure what I should do about the end joists (blue 2x10s in link) http://img.photobucket.com/albums/v738/ARTHUR101/bbbbbbbb.jpg?t=1179719565 Should I use the joist hangers and bend the outside tab flat against the green 2x10s(in link) joist?


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## Big Mackey (May 18, 2007)

I ended up using concealed flange joist hangers for the end 2x10s.


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## Big Mackey (May 18, 2007)

*Update*

I was going to use Z brackets to attach the vertical 2x4 to the 2x10s and 2x8s, I was told they cost $0.25 each But when I got to the hardware store they were $1.60 each. Well.... I needed 44 of them  So, I decided to redesign the walls of the frame.

This is what I have built, The studs are 11-1/2" on center with a removable stud to access the pump/heater. http://img.photobucket.com/albums/v738/ARTHUR101/222.jpg?t=1180682983 

The bottom of the hot-tub(foot well) that sits on the frame is only about 2'x3' and it is NOT level, There is about a 1-1/2" gap in-between the foot well and the frame on one side. (Yes it's the hot-tub, Not the frame :laughing: Originally the hot-tub was sitting on drywall compound/Spackle.

It's going to be outside, So I want to use something water proof to fill the gap. After seeing the post about concrete, I think that's what I want to use.

I don't want to add another 200 pounds to the frame, So I want to make some light-weight concrete by using perlite in the mix.

I have never worked with concrete before, So I have some questions.

What kind of concrete should I buy? (preferably from Homedepot) 

How much perlite should I mix in? I want it as lightweight as possible (keep in mind the hot-tub was sitting on drywall compound)

Should I pour the concrete directly onto the plywood or should I use a plastic sheet in-between the concrete and plywood? (I will be using a plastic sheet in-between the hot-tub and concrete)

How long will it take for the concrete to harden enough before we can use the hot-tub?

I'll post some pictures tomorrow.


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