heavy duty deck - help?

[bryceaugustine]

Quarantine has me thinking about a lot of things, cars and trucks, boom boom sticks, home improvements etc. I thought of something, and now i need to know how it would be implemented, because i just want to learn and know.

ok, so suppose someone wants a deck that is heavy duty and can support weight. all things are possible, it is just making sure they are designed/engineered and built correctly.

This theoretical deck will be as close the ground a possible. it would be 24'x24' (576 sqft). there would be a pool on the deck. the pool is 22'x52". Total volume of the pool is 12,322.22 US gallons. The pool is obviously will not be filled to the brim, but we will use that number anyways. 1 US gallon of water weighs 8.34 lbs.

so 12,322.22gal x 8.34 lbs =102,767.32lbs of H2O

102,767.32lbs / 576 sqft = 178.42 lbs per sqft

for the sake of saying so, lets round it up to a nice 200 lbs per sqft...how would a a deck be built to support 200 lbs per sqft?

what would be needed? 8"x"8 posts, like everywhere? concrete pillars? 2x12 sandwiched together to create the beams and joists? LVL's needed?

also, please correct any math I may have wrong.

 

[Dustball]

How about a concrete pad with a sleeper system?

 

[MushCreek]

I think you're in to steel and concrete territory. I have a friend who had a loft built in his barn for tractor storage, and it was built to 160 lbs/sq/ft. Steel beams, and steel pans filled with concrete. A little heavier construction, and you're there. Obviously, it would need to be engineered, and wouldn't be cheap.

 

[tomtomgt356]

How deep is this pool? Based on your volume in gallons, and 7.48 gallons/cubic foot, I'm getting 17.3' deep, which doesn't make sense if it is 4'-4" wide. Also, if the pool is 22'x52", the weight would be over 95.3 SF which would be 1,078 lbs/sf. Numbers aren't adding up. Is the pool 22'x22'x52"? If that is the case, the deck need to support 212.3 lbs/sf

Since you are trying to build it as close to the ground as possible, what about putting the pool on the ground (or on a concrete pad to get the top to the deck level) then build the deck around the pool? That way the deck is just supporting normal foot traffic.

 

[matt_i]

Do you want the bottom of the pool to sit on top of a wooden deck? Or the lip of the pool to be flush/level-ish with the top of the deck?

Just asking because there aren't any pools made which can be supported by the lip around their perimeter....the pool has to sit on something solid.

That drives me back to the deck sits under the bottom of the pool...maybe a double-decker?

In any case I'd look at the column spacing to start. Suppose you can use 2000 psf for soil bearing, assuming you don't want to drill to bedrock with higher bearing. Approx 240 gallons of water can be concentrated on the 1sqft (2000 lb/8.34lb/gal). Approx 7.5 gallons/1ft^3. (240gal/7.5gal/ft^3). Roughly 32 ft^3 of water. Depth is fixed at 4.3ft, (52"/12"/ft) which corresponds to 7.45sqft of water-area. Take SQRT(7.45) to get 2.7 ft x 2.7ft. Don't know the weight of the pool itself but its roughly 24" on-center post spacing. Each sitting on 1sqft of concrete.

I think you'd be better off to pour a 8" concrete slab, reinforced, then start setting your posts.

Bottom line is its silly expensive in concrete, wood, and prep as compared to sitting it on the soil.

 

[CraigStu]

...
Bottom line is its silly expensive in concrete, wood, and prep as compared to sitting it on the soil.

I agree. Sit it on the ground and build around it. Depending on the pool and deck details, I'd try to build the edges of the deck at the pool from Trex or similar so splinter injuries won't be a problem in the future.

 

[Kaizen]

Yea that gets into loads above what would be economical to build with wood.
Since we are going down this imaginary trail. If we did spend ten times as much as steel and concrete cost and used wood. Would the water itself sloshing around be enough to destroy it? Like a pallet in a plane that is not tied down and affects the trim characteristics?


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[bryceaugustine]

There is a lot of great thought here. The thought of putting the pool on something was that in KS we get like 4 maybe 5 good months to use a pool (and that is pushing it). So if there is something solid under the pool you have a space you can use when the pool is down. It is not a metal sided one that is left up all year. It comes down and goes in to storage to prolong the lifespan.

@MushCreek I am envisioning a barn back east built into a hill with an entrance at the bottom of the hill and one at the top. I either saw someone doing rehab on one here or TV a few years back.

@tomtomgt356 the pool is 22' round 52" deep. I used this calculator to get the gallons of the pool. https://www.calculatorsoup.com/calculators/construction/tank.php

@matt_i thanks. yes silly expensive no matter how you cut it. the idea was that the pool did sit on top of the deck. would 8" of concrete be enough?

@Kaizen great question. I surely do not know the answer.

 

[firebirdparts]

Joist design is trivial, really, you just shorten them. If you take a typical simple house and cut the simple lengths in half, you cut the forces by a factor of 4, and that's all you need to do.

Post size is technically irrelevant, but you can use 6x6's and they'll look heavy and you'll feel better. Your post foundations, on the other hand, need to be 4X, and they are going to cover quite a bit of ground.

now, if you don't want short wood, then okay. Steel it is.

Cross bracing it so that that the posts don't fall over becomes more interesting as the posts get shorter.

 

[nh_yota]

Sit the pool directly on the ground and build the deck around it or pour an elevated concrete pad if you want to raise it up.

Wood decks are great until they start to rot.

 

[SGKent]

the standard way of having a doughboy pool and deck is to put the doughboy on the ground and build the deck around it so you don't have to climb up a ladder to get into the pool. Photo from zagerspoolspa.com.

 

[TRWham]

...

Post size is technically irrelevant, ....

So you mean I wasted all that time applying Euler theory on posts and columns in statics class?

 

[ycgoat]

I doubt you would support a 20’+ pool using wood but you can check the RBC or IBC code tables for common materials


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[Joe Reed]

I would think that for the cost of doing what you're proposing correctly you might be approaching the cost of an in-ground pool...

 

[MoonRise]

That's no longer a "deck", but a "pool support structure".

Can't use "deck" construction plans or materials or construction or methods, as it's no longer a deck.

You would need to get actual engineered plans (with the engineer being an actual Licensed Professional Engineer who will also use their PE Stamp on those plans).

Not that it really matters here. Cause unless your name is Bezos or Gates or similar, this idea is probably not going to happen because of $$$$.

FYI, and no matter what, the MINIMUM required size for a deck post is 6x6.

No more 4x4 deck posts allowed, as of a few years ago. Too many deck failures and injuries and deaths.

Put the pool on the 'proper' substrate on the ground, then you can build a deck around it so that the deck is up near the top of the pool. Just like the image posted by SGKent above.

Or build the pool on the ground (again on the 'proper' substrate) and then build a ground-level 'boardwalk' around the pool.

Don't want that 'hole' in your deck? You'd need to figure out some sort of replaceable 'deck panels' to fill the space when the pool isn't in the hole.

And pools and decks REQUIRE building permit(s). Anything more than a 'temp' kiddie or Intex type pool anyway.

Structural requirements.

Electrical requirements.

Setbacks from the house or any other 'structure' (because of folks who attempt to use that 'structure' as an impromptu diving/jumping platform, whether they say 'Here, hold my beer and watch this' or not. Like my one cousin who did that from a detached garage to the above ground pool, several times, in his youth. And missed the pool several times IIRC. To the tune of several HUNDRED stitches because he landed on 'stuff' around the pool.) as well as from property lines and underground stuff (utility lines or septic lines/fields).

Etc.

math check:

22' diameter pool, 52" deep is

pi x r^2 x depth = 1647 ft3 of water.

Round off to 1650 ft3.

7.5 gallon / ft3 = 12,375 gallons

8.3 lbs / gallon water weight = 102,712.5 lbs of water

Your math is correct there.

But the idea of putting 100k+ lbs of water on top of a 'deck' just is NOT going to happen or be approved by the Permit folks.

With Bezos or Gates level of money, it -could- happen.

But why?

 

[Joemctag]

What I’m hearing OP say is: “...just want to learn and know.” “This theoretical deck will be as close (to) the ground as possible.” “So if there is something solid under the pool you have a space you can use when the pool is down.” “It is not ...: one that is left up all year. It comes down ...”
Kind of pool he’s talking about you normally level an area, then a couple inches sand and level that so reinf. fabric bottom has uniform support and nothing to puncture it. Then set pool on it . Pool assumes its final shape as it’s filled. Then can erect deck if desired. But to take it down every year you’d have to move the deck unless it’s a small one on one side. Also, when you set the deck up next year, its rim might be a few inches different from where it was before. Flat slab seems obvious solution. Wood deck , even with no posts and lumber sitting on closely-spaced bricks or blocks seems do-able if you don’t want a (permanent) slab.

 

[ManOnTheCouch]

The OP might be better off putting the pool on the ground and building a deck around it + building deck inserts/platforms that could be put on/into the deck when the pool is remov d for the winter.

 

[speed bump]

You are looking at a 22x12.5x6 ft pool with the numbers you are talking for gallons. For that size put it on the ground unless it just has to be elevated.

If it has to be elevated I would skip right past wood and go steel and reinforced concrete. Figure if your pool weight is 200 PSF your deck needs to hit 240 PSF (because if we have a pool we need to have parties). I would probably attack this in two directions at this point, I would get a soil bearing test to figure out what I will need to do on the bottom and obtain a copy of whatever publication is the guiding document for elevated pool construction and a copy of the AISC manual of steel construction so I could start spec'ing the deck. Once you know the soil design limits you can spec your piers and footers and start optimizing costs and layout between for footers and deck supports. At this point I would take that information throw it in the garbage and call someone to make an elevated pool appear because if you have the funds to accomplish a project like this and don't know the first place to start you should be paying someone because your time is much better spent doing what your are highly paid to do.

 

[nadogail]

If you drive 100 piles to bedrock and use 12 X 12 Cross Beams, everything through bolted with 1.5" diameter Grade 8 bolts, IMHO that should be strong enough.

 

[rlitman]

...This theoretical deck will be as close the ground a possible. ... there would be a pool on the deck. the pool is 22'x52". ...

I believe you are describing the sort of deck that's more commonly known as a "patio".