Suspended Waterproof Floor

[Lazymule]

Back with another unhinged problem. I'll start with I need to build a 20x20 floor for a carport structure that can get extremely wet, that is also hovering above the ground. Now that your hooked, here is the back story. Young vegetable farmers here on leased land for 10 years. We need to redo what we call a "wash/Pack" building. The best option in our budget is a carport type tubular steel structure. We spray water everywhere, wash carrots, bins etc. We use drains and stainless sinks etc to be somewhat good about water and drainage, but at the end of the day stuff just hits the ground and its nice to mop up or just hose down the floor. If we were smart, wealthy and had better land lords, I like every produce farm ever would just pours a slab. My primary issues are the land we lease is not actually flat, Approximately 7" of drop one 20' direction and 3" the other direction and I have to take this all apart when I go.

So where I'm at is I can build a deck that is supported by concrete columns. I would like this deck to be a flush beam style, so my floor joist and rim joists are all supported to these support columns. Not beams on columns, with floor joists above because I want this floating deck as low to the ground as possible so we can just wheel carts in and out with a minimal ramp threshold. Also I will give the whole building about 2% slope so water will drain out. The carport will go above on this deck and we will hold the siding about 6" off the ground so everything can have airflow around it. That said how would you make the floor so you could just go ham with water. Also no cars trucks forklifts etc will be driving on this deck. a few 200 gallon troughs of water and sometimes 1000# produce, 3-4 people working.

Idea I looked into was stolen from having a garage over a basement. Would it be crazy to use the metal form deck and actually pour concrete just up on a deck? Will this just be crazy expensive?

Should I just do plywood and some crazy paint on sealer. T&Gboards? Car Decking?

All ideas welcome. The more cost effective the better I guess.

 

[BurtEggley]

take tours of facilities that are used in your industry. There may be other simpler and less costly solutions.

 

[strength_and_power]

Build your deck and put a roof membrane on top or to go super cheap, get some of those billboard signs turned into tarps. On top of that, lay rubber mats with holes in them like you’d see at a kitchen so water drains and the mats would help
Protect the membrane. Slope it so you can drain it to a gutter on a side you don’t need access to. Collecti it in a barrel to be used again or pump it to a field and water your crops

 

[kyrbz]

I posted in another thread about an adjustable pedestal system I’m using for a Japanese style wet bathroom to create an elevated tile floor. They’re plastic caps designed to be used with standard pvc that allow adjustable heights and angles. They’re often used for decks on roofs. You might be able to make plywood “tiles” that are sealed and use a system like this. To minimize the number of pedestals maybe make the plywood “tiles” 4’x4’ using 2x material on the underside for reinforcement. Their whole thing could be easily disassembled and reused when you’re done. Here’s a link to pics -

https://www.garagejournal.com/forum/threads/what-did-you-buy-yourself-today.445359/post-11487793

 

[Firebrick43]

leveling the ground with a tracked skid steer and pouring a slab will be much cheaper

 

[finn]

Use large paver slabs, available at Menards or whatever is equivalent in your area. Water will drain through the perimeter gaps, and they’re cheaper than building a deck.

if it’s important that the floor is level, bring in gravel. I doubt if that’s critical, though.

 

[BillK]

By the time you are done designing and figuring out how to build some crazy system like you describe, I think you will be cheaper and faster in the long run to just have a slab poured. No need for any crazy prep. Just have a 3" slab framed out and poured. If I figured it right you are looking at a little less than 4 yards of concrete.

 

[jblnut]

I was going to suggest pavers as well.

If you build a wooden floor system make it in less than 8’ widths so you can potentially lift it up and transport it to the next location. This would be the most versatile. Like someone else said, build it out of treated wood and cover it with some sort of water prior layer like a thick tarp or rubber mats.

Another option is to lay marine grade plywood down and replace it as it rots. I’d think It’ll last 10yrs before you have issues though.

Is a thin slab really not an option ? So what if you have to tear it out when you’re done. Get a skid loader rented for a day and toss it in a roll off. That really would be the best solution for the water part of the equation.

Better yet. Build your deck system and top it with a thin layer of concrete. Build it in sections small enough you can move them with a skid loader so you can stack them up like giant pavers.

You could always say hell with it and move up here and become a snow plow and lawn care business lol.

 

[Badhabit]

What if you built a pole barn of the size that you want and build a raised floor attached to the poles. I'm thinking metal decking with about 2" of concrete. That is how second story decks are build around here and we get lots of frost. When your lease is up, the concrete floor could be broken up and the deck underneath could probably be salvaged. The rest of the building could be taken apart and the poles dug up. I have used lots of salvaged deck for fences, wind breaks etc

H

 

[theoldwizard1]

Your biggest problem is going to be preparing the ground UNDER your "floor" and having a place for the water "to go" !

Under the floor, remove about 6" - 8" of soil, enough to make a flat base. Frame the area with PT 2x8 staked with 1' stakes. Bring in crushed rock (no fines). Add rock in multiple lifts. Compact each lift. The final lift should be several inches "above grade". Set your drainage angle with the final lift. Then ...

Use large paver slabs, available at Menards or whatever is equivalent in your area. Water will drain through the perimeter gaps, and they’re cheaper than building a deck.

The gravel will provide drainage. Make sure the the PT "frame" hold the pavers in place. You will need to provide "footings" under where the carport columns are going to sit so that window can't cause it to take off.

Depending on the soil, you may need some kind of dry well to help disperse the run off.

 

[ADKAmateur]

I had a brilliant idea of using helical piles and Coosa board which is a fiberglass panel used instead of marine plywood in shipbuilding. Then I saw the paver suggestions. That is by far the most elegant solution. Cheap, easy to install, self draining and you can take it apart and move it all to the next location. You can get some pretty large pavers nowadays if you want to minimize the number of pieces.

 

[ADKAmateur]

I had a brilliant idea of using helical piles and Coosa board which is a fiberglass panel used instead of marine plywood in shipbuilding. Then I saw the paver suggestions. That is by far the most elegant solution. Cheap, easy to install, self draining and you can take it apart and move it all to the next location. You can get some pretty large pavers nowadays if you want to minimize the number of pieces.

 

[Hank11]

Just pour a thin slab and get this over with. Any kind of a raised deck is gonna present problems of debris being caught underneath it or around it and it’s gonna be a contamination issue cause you can’t really clean it and it can’t really dry out thoroughly.

When you leave, just have the slab demoed. Or it might turn out that your landlord doesn’t care if there’s a slab left behind.

 

[theoldwizard1]

I had a brilliant idea of using helical piles and Coosa board ...

Good stuff ! INCREDIBLY EXPENSIVE !

 

[theoldwizard1]

Just pour a thin slab and get this over with.

Gravel. Cheap pavers. Much less expensive !

 

[Lazymule]

Ok sounds like my idea is mostly crazy and likely expensive.

Also seems like everyone is voting for slab of some sort, which does honestly solve all my problems. So this leads to some more questions.

What do folks feel like the minimum excavation of top soil would be before compacted gravel? I'll add that the slab will need to be brought up in grade on the low side (more gravel) because we will mostly be walking and wheeling the produce into the building from the uphill side where all the fields are, but we could do the whole slab at a 2-3% slope. What is the thickness folks would recommend for a slab thats not really holding too much weight and might have to be moved. I'm not really that worried about destroying the slab, but more worried about removing all the gravel and filling in the hole left behind from excavating the top soil. I guess I could just pile the soil somewhere out of the way and save it?

What would be best practice here to attach the carport. If the slab has slope whats the best idea to get it level for attaching the carport. Also due to the snow and wind load I'd guess I'd need some sort of better concrete foot/stem wall? Thanks everyone

 

[Kaizen]

Plastic pallets.bolt them all together and call it a day

 

[tarbellb]

Compact and grade soil
_heavy tarp/roofing membrane/repurposed vinyl
__ plastic pallets bolted together

 

[racecougar]

What would be best practice here to attach the carport. If the slab has slope whats the best idea to get it level for attaching the carport. Also due to the snow and wind load I'd guess I'd need some sort of better concrete foot/stem wall? Thanks everyone

Assuming it's the typical tubular steel carports, bolt it to the pad. The legs of the carport are adjustable. Since you mention snow load, you must be somewhere that freezes, so look into a thickened edge slab.

 

[Skiff Builder]

I would do it in fiberglass:
Build frame, slight angle for drainage
Deck it with 3/4' BCX ply- forget Coosa and it's exotic cost for your application.
Glass it with 1.5oz chopped strand mat and poly resin
Finish with Gelcoat ( Porch paint is an option).
Will last twice as long as you need it. Easily repairable if needed.

We did a 385 sq ft deck- did all glass in one day, 2 people. Was the best cost option for any waterproof system.
35 yds of 50" mat- $150
10 gal resin- $500
5 gal gelcoat- $250
2 gal bondo- $100
Sundries-$100

See link to my post on building it
https://www.garagejournal.com/forum/threads/composite-deck-build-over-a-garage-door.380497/

 

[BombShelter]

I used to sell fiberglass grating to a food prep company that did airline meals, they'd easily wash down the open floor at night with an underfloor drain system. Fiberglass comes in both pultruded (looks like mini I-beams) or molded (looks like squares).

I'd look for surplus metal or fiberglass grating, throw it on some diamond piers with wood supports. If you had to move it, it wouldn't be too hard.

 

[firebirdparts]

It's not ridiculously expensive to do concrete on decking, but I would think something like treated wood and trex would be a lot cheaper and drain better.

 

[Codyboy]

How about a grid like this?
Place on top of some crushed rock thats been leveled and graded to drain well. Water won't puddle and looks like would be plenty of traction.
Could probably even fill with more clean rock.

AgTec 15.7in x 19.7in Heavy Duty Grass Gravel and Paddock Pavers - Ground Stabilization and Mud Control Grid System

These extremely rugged grass, gravel and paddock pavers have an extremely high 1350PSI (228,300 lb) load capacity and made from an extra strong 100% recycled patented plastic blend making them perfect for equine and parking use.

www.agtec.com