Quonset flooring

Hey GRM!

Life has been busy lately, primarily with purchasing a new house and selling our current place. We're going from inside the city to about 20 minutes outside, on 13 acres. Tons of room for projects!

One of the included outbuildings is a roughly 30x60 Quonset that the previous owners flooded and used as a skating/hockey rink during the cold months. I'd like to use it as vehicle parking/storage, but I'm not sure of the best way to accomplish this. My goal is minimum amount of humidity to prevent rust. The floor currently has a one piece plastic sheet covering the entire thing. Underneath looks like very wet gravel/mud. 

Would it be best to add a layer of gravel on top of this and park cars? Remove the plastic and add gravel as needed once it dries out? Remove the plastic, let it dry, then re-install and cover with gravel?

That is so cool. Congrats on the acreage. I wish I had a spare Quonset hut to flood and make an ice hockey rink in; my kids would have a blast and only the occasional broken limb. I don't have any tips on how to floor it dryly though sorry. My uninformed thought process would be that getting the moisture out is important and the plastic would be preventing that. Putting gravel on top would almost certainly result in torn plastic so it would continue to emit moisture into the air. But I don't know how dry your climate is there; would a bare indoor gravel floor ever be "dry?"

You won't be able to control humidity with any type of flooring. You have to manage the water and ventilation. 
 

I don't know anything about your typical weather patterns. Google says prairie winds, but generally high humidity.  The humidity inside the building will mimic the exterior without mechanical aid.  (Humidity will always migrate to the drier space)

First question is about grade. Quonset hits have no overhang.  100% of the rainwater that lands on the roof ends up pooling at the base of the walls.  If the grade inside is lower than the grade outside, it will always be wet. It's basically a small pond with walls around it. Previous owner definitely contributed to the issue by flooding the building regularly.  Even a single pinhole would allow all that water to seep under the plastic, and the plastic then prevents evaporation. 
 

First you have to dry out the building.  Remove all the plastic and encourage airflow. Large fans may help.  Measure and monitor the actual moisture levels in the soil.  Drying out the building will take a long time. Probably weeks or months.

Once you've got the building dry, then you need a plan to manage the water. You can't add gutters to a Quonset hut, so I would suggest adding French drains on each side at the base of the walls.  Drain to daylight.

If you are able to successfully dry out the floor, then you can think about the flooring.  I would consider avoiding the vapor barrier and adding a permeable floor.  That way the floor can breath and dry to the inside (with ventilation fans).  For a floor surface, consider GAB (crush and run).  It's gravel that can be packed tightly and can serve as a reasonable parking surface that can still drain and breath.  
 

If you want a finished floor (like a shop),  the plan would be different.  Concrete, with vapor barrier under.  If you can't mange humidity with ventilation alone, consider dehumidifiers and/or HVAC systems.  That would  get spendy.

BTW, you can dry it quicker if you turn the dirt a few times with a machine. Mini ex, farm tractor, skid steer, rototiller, whatever.  Just turn the dirt every few days to get air in it.  

I once visited a guy who had an impressive collection of old project cars , 

When he parked them they were rust free , but he put plastic on the ground  which kept the water from draining . so there was always moisture under these cars and they rotted so bad they were barely parts cars !

right now if you went out and dug a hole , how deep before you hit damp soil ?

Long time no update!

Old house is finally sold and emptied, just have to wait for possession. Raining all day today, so I was able to take the time to set up my computer and spend a day relaxing. 

I've removed all the plastic and have had a air blower going, a bit blocked by some cars I put in there. Front area is dry, back is still wet. You can see the moss growing in the front corners where the air doesn't move. I need to get another blower and also move this one around.

I had noticed in the far corners some mostly buried drainage hoses when I first pulled up the plastic. 

Well I was weedwhacking all around the buildings yesterday and found their exit

So there's some drainage made. I'll probably leave it for this winter, and revisit in the spring how much additional drainage I put in and what kind of additional flooring I put in. Hopefully maybe DIY with my own tractor...

In reply to Run_Away :

This is a system that might be interesting to look into:

http://Airfloor
 

I have no idea what the cost is like. It might be reasonable, it might be astronomical. I saw it used recently, and it's intriguing. 
 

Basically they are forms that are placed on the ground before a concrete pour, and they create voids underneath for airflow. They are designed be used with forced air systems. Basically the HVAC is circulated under the floor without ductwork making a giant forced air radiant slab. 
 

It may be more than you want to consider, but it would give you ventilation, a finished floor, and conditioned space all in one. 

That is interesting. 

I would definitely like to add more work space. I can either use the attached garage, build a new shop, or develop this quonset. Using the garage means building another covered parking area for SWMBO's car and some of my more "finished" projects. Building a fresh workshop is the most money but I can spec exactly what I want. This quonset is workable, but also a fair bit of work to get dry, tight, and warm. Someone mentioned building a wall halfway through and just putting down concrete and insulating the walls for half the building to keep building and heating costs in check. 

I have a quonset of sorts. A fabric coverall type building 30 by 45 feet. I put poly down and then 2x4 sleepers with aggregate between them, and plywood over top for a floor. It is almost 20 years old now and in great shape and moisture free. The trick is to have air movement of some kind. I really like working on the plywood. Easy in the knees.

I would use the attached garage as a last resort, or at least only temporarily till you can get another work space up and going. Keep SWMBO happy and able to park in the attached. Plus, a detached shop keeps smells and fumes from permeating the house. 

Very interesting how the quonset is attached to the footer. We have two, one bolted to a wood floor 5' off the ground and another bolted to a concrete pad. No worries about seepage backunder on yours, but maybe a rusty worry? After 30 years we had to replace all the panels around the bottom of ours from rust, but thankfully not terribly much work. 

Moisture is the enemy of cars!  As one who has enjoyed moisture issues, even in a concrete slab steel building, I say dig the soil out to a level you can put down a moisture barrier and pour a concrete slab.  The hut sits on concrete footers, so you have your perimeter.  Otherwise, get rid of the cars.  They'll dissolve into rust sitting on that damp soil, or worse, stuff will just randomly quit working due to corrosion.  

Concerning ventilation.

Something I've been wanting to do to my garage ( steel framed and covered building on a 3 ft high concrete block perimeter ) is to add a heat exchanger that is used in tight houses.  This is set up to reclaim heat / cooling while allowing fresh air to enter.  The only operational costs are electricity to power the blower and filter replacement.

I'd add outside / inside temp sensors / humidistats / control PLC.  In the summer if it is cool and humid at night, heat can be extracted from the building without bringing humidity inside. In winter, heat can be brought in even if it is humid outside.    

I'd alter the system to allow warm dry air to directly enter the building in the winter / cool dry air in the summer. With a lot of thermal mass in the garage, warm and cool are relative terms.