I know there was a thread on this years ago - floor for car port / barn

So I remember there being a thread about this a number of years ago, but I can't find it.  Someone on here bought or had a house with an aluminum car port barn, with dirt floor and wanted to add a more permanent floor.  I'm now in a similar situation.

We've just bought a duplex 'Up North' with one half as an annual rental, and the other half weekly Airbnb / our own use.  On the property there's a simple metal 'barn' building, fully enclosed on three sides, with a roll up canvas 'door'.  Right now the floor is just dirt, it was used for lawn equipment, and I assume 'toys' in the past.  I've no plans to use it as a workshop or garage, but I do want to use it for storage.  Specifically our pop up camper, small sail boat, and possibly my Boxster during the winter.  The thing is the water table is quite high, and I don't' want moisture 'wicking' up and getting at the metal things stored in there for long periods of time.

I want to add some kind of cheap, level-ish, dry floor.  Here are some pics.  Size is 20' wide, 24' deep.  

As you can see the 'floor' is just dirt about level with the ground, and yes there's a slight gap at the back that needs to be leveled up from both the inside and outside.

What I'm thinking is:

• Level with rake
• Sand layer for final leveling
• Visqueen plastic as vapor barrier - 6mil?  Tape overlapping joints or just large overlap?
• Cheap 2'x2' paving slabs

IS that the right / best / cheapest way to do it, or should I put the sand on top of the vapor barrier?  Other suggestions than paving slabs?  I had a friend who used visqueen and capet for many years to good effect, but he was lucky and found someone who was tearing up a massive area of carpet.  I've not seen anything like that I could pick up cheap.

Note, right now there is no power to the building.  I am thinking of getting 30amp circuit run out there just for battery tenders, and possibly to keep a golf cart on charge for getting to and from the beach, but I'm not sure on that.  Also I've thought about a couple of cheap hammer store solar panels and a couple of deep cycle batteries for basic lights etc. and nothing else.

Thoughts?  Suggestions?

TIA

I'm not saying that carpet is right but to find used carpet, find a carpet store. New carpet gets installed and old carpet comes back to the stores dumpster. The store then pays dumpster fees to have it hauled away. I'm sure they'd rather see you take it. 

Congrats on purchase.!

What town he asking knowing that he's likely to rent a place up there from someone.  Typically in Boyne, Charlevoix, Petoskey area. 

In reply to John Welsh :

Frankfort.  Exactly one mile from the Lake Michigan beach, four blocks from 'Lake Betsie'.  Made for a lovely morning walk with the dog to grab coffee, walk to the beach then 'home'.  I will shamelessly advertise here next summer when we're ready to rent.

In reply to Adrian_Thompson (Forum Supporter) :

A beautiful area too. 

Plastic sheeting as a vapor barrier makes sense to me, but when I think of visqueen I think of the plain unreinforced stuff. I would go for the stuff that has fiber string reinforcement like they use for crawlspaces and such. Maybe that's what you mean, but I wanted to make sure.

That's a beautiful area, I would love to airbnb in something like that.

If you were close to me I would offer to coordinate giving you my current patio stones, they're old worn 2'x2' concrete pavers that I need to replace. Perfect for something like that, but getting them would probably cost you more than they're worth.

In reply to John Welsh :

Off topic, we've also spent a lot of time in Petoskey, Harbor Springs, Charlevoix and love it there too, especially the access to M119, the tunnel of trees, Good Heart, Cross village, Pond hill farms, Boyne Highlands etc.  But after much debate we've decided upon the TC/Leelanau/Crystal lake triangle to settle as long term when we're older TC has a big hospital, all the big box stores, a more developed arts/theater scene etc.  IT was a tough choice 20 years in the making.  

Can you provide more information on the canvas door? 

You have inadvertently created the exact same thread ive been thinking about making, with the same use cases. Inly i dont have the canvas doors yet, and way more slope to deal with. 

Id been thinking about a 2x6 subfloor on 12 inch centers, with crossbracing every 18 inches, then topped with two layers of 3/4 ply as a floor. Should  e almost rot proof on top of the vapor barrier being pressure treated, and strong enough to park the race cars on. 

If the goal of the vapor barrier is to prevent moisture from entering the building, it's important to mention that vapor barriers prevent moisture movement in both directions. So anything that comes in wet and drips onto the floor will be adding moisture that could take quite awhile to leave. Even on days with no precipitation, that metal will likely "sweat" and drip condensation that will eventually get caught by the vapor barrier and retained in the building.

What I'm trying to say, is that there is no cheap and easy way to store things that you care about to avoid rust or damage from moisture. Especially in a leaky building shell like that.

In reply to Adrian_Thompson (Forum Supporter) :

For me, maternal grandfather was born in East Jordan and grandmother was born in Boyne City...in 1899...imagine!

At 55 yrs old, Im the product if older parents who were the product of older parents

The grands moved away but retired back there. As kids, that's what we did for the summers.  They have since passed but grandmother lived to be 98. The house was sold but the area is  still the "motherland" and we visit often. 

In reply to STM317 :

Good point on the vapor barrier being a two way deal.  The water table is relatively high there, so I am more worried about from below than above, but still a good point.  Is there a better material for the vapor barrier?  

My parents are on the other side of the lake from you, but have the same high water table issue. Even in their concrete garage, they get condensation, quite often. 

I think that STM317  has a really good point here. I don't think a vapor barrier will help you, in fact, it may make it worse. I would consider a wood floor, like a shed. Angle it slightly so that any runoff that does accumulate will drain. Consider it a replace-every-20-years type of thing. 

Add some sort of exhaust fan? Let some air in to carry moisture out.

I like the paving stones / barrier idea.

Call your local concrete company and ask for flow fill. If they have it ask them if they'll add a couple sacks of cement to it. People sometimes call it CMU or structual fill although it's not exactly that.

It comes in a concrete truck and is self leveling. At one time here it was $120  for an entire 10 cubic yard truck

Also to add to this though is it does take some time to dry but the surface is pretty strong afterwards. 

mtn said:

My parents are on the other side of the lake from you, but have the same high water table issue. Even in their concrete garage, they get condensation, quite often. 

I think that STM317  has a really good point here. I don't think a vapor barrier will help you, in fact, it may make it worse. I would consider a wood floor, like a shed. Angle it slightly so that any runoff that does accumulate will drain. Consider it a replace-every-20-years type of thing. 

 

Talk to me about the wooden floor.  How is it supported?  We've got a deck behind out house down state that I put in about 15 years ago.  When I built it, there was an air gap under all joists and the ground.  Over the years as the grass etc. died off under there, it seems like the top layer of soil became less dense and rose up to meet the underside of the joists and rotted them out in one area.  How do you stop the wood instantly starting to rot out, even if assume periodic replacement.  

In reply to Gearheadotaku (Forum Supporter) :

I like the fan idea, it could be run off a solor panel on the back wall (South facing).

Adrian_Thompson (Forum Supporter) said:

In reply to STM317 :

Good point on the vapor barrier being a two way deal.  The water table is relatively high there, so I am more worried about from below than above, but still a good point.  Is there a better material for the vapor barrier?  

I think if you're considering floors that are pretty porous, or comprised of multiple pieces any vapor barrier is kind of a waste. For a harder, less permeable floor like the concrete product Antihero mentioned I think it's the best choice.

In reply to Antihero (Forum Supporter) :

Talk to me about flow fill and it's strength, uses, thicknesses needed etc.  An exhaustive Google search lasting a good 3-4 minuets indicates its usually used below grade for quick easy reinforcements where compacted earth would be an issue, expensive, and or very time consuming.  I saw terms like 'strength similar to surrounding earth etc.  I've always thought (to an extent) that the more dry you concrete mix, the higher the strength and that a slurry type concrete mix like this would be very very low strength.  But I'm not intending this to be a working shop.  As I said it would be a storage shed, not a workshop.  I would want to be able to do things like remove the wheel, hub etc. on the camper to re-pack wheel bearings etc.  SO I assume I'd need a nice big 12x24 plywood load spreader before putting a jack under anything.  What other prep is needed?  Mesh reinforcement?

Having hit up the big orange box website this morning I'm seeing the cheapest pavers I can see there are $1.51 Sq/ft in bulk, which puts the cost before anything else around $370 (allowing for a couple of damaged ones during placing them), which is honestly pretty good.  Adding $100 for vapor barrier plus $100 for other consumables we're still under $600.  If Flow Fill is really $150-200 for 10 yards, which would be enough for 6" with a yard to spare.  

In reply to Adrian_Thompson (Forum Supporter) :

Adding cement to it does not make it concrete. Think of it as stronger than fill but massively less strong than concrete. The idea on the added concrete is to make the surface bind together. You can also sprinkle cement dust on the finish product and compact it in too although penetration isn't great.

Flowfill is primarily used as fill under slabs, mostly because it's very easy and reaches 100 percent compaction without any extra work( because of the water). I've used it many many times and have driven fully loaded concrete trucks on it (60-70k pounds) with no real problems.

Adding cement to the mix just makes the surface more durable and you'd have no trouble using a jack on it. I'd still add a plywood base just because but you probably won't need it.

No prep is needed, you spread it and walk away. We would usually set up grade pins and screed it if it was very important for it to be a certain level but a rake is fine. The added cement makes it a bit harder to move after it dries but it's still doable. For example with the added cement we would carve stairs with it and it would hold it's shape long enough for us to pour actual steps over the top

In reply to Antihero (Forum Supporter) :

Is it literally a back up and pour to depth?, no vapor barrier needed?  I take it assuming there are no leak paths, I could literally set up a 1/2-1" board across the opening and pour to that level.  No need to push around a broom or trowel while standing in 6" of soggy flow fill?  No need to hire someone for finishing?  I've finished 9x9 pads where I havre access all around, but don't fancy 240 sq/ft with no access on three sides.

I've used 'mudcrete' before where I've mixed bags of Portland cement with the existing earth, roughly leveled it, let the moisture from the soil and atmosphere cure it, and made a nice pad for my lean too wood shed.  I take it flow fill is a similar theory, a solid base.  

Adrian_Thompson (Forum Supporter) said:

mtn said:

My parents are on the other side of the lake from you, but have the same high water table issue. Even in their concrete garage, they get condensation, quite often. 

I think that STM317  has a really good point here. I don't think a vapor barrier will help you, in fact, it may make it worse. I would consider a wood floor, like a shed. Angle it slightly so that any runoff that does accumulate will drain. Consider it a replace-every-20-years type of thing. 

 

Talk to me about the wooden floor.  How is it supported?  We've got a deck behind out house down state that I put in about 15 years ago.  When I built it, there was an air gap under all joists and the ground.  Over the years as the grass etc. died off under there, it seems like the top layer of soil became less dense and rose up to meet the underside of the joists and rotted them out in one area.  How do you stop the wood instantly starting to rot out, even if assume periodic replacement.  

My parents place has been in the family for about 5 years. The shed is probably 50+ years old. Who knows how old the floor is. The shed stores outdoor furniture (plastic), an ice hut, some wood, and occasionally some bicycles and small boats (not all at the same time, too small for that). 

I don't know how it was built, but my brother and I scoped out rebuilding the floor, or rebuilding the entire shed. Because of what it is, and what it is used for, we decided to go the super cheap way out - we simply put new plywood over the old plywood - keep in mind that we have a 40x24 shop, and a 2 car attached garage, so we were looking for "good enough". 

But when we were scoping rebuilding the floor and/or starting over, we decided that if it didn't get a poured concrete floor, we would have gone with the following process: dig out the soil, put a weed barrier fabric over that, gravel, put the joists on concrete blocks, then build the floor over that. I can't recall if we thought we were going to dig the joist supports deeper. I do remember discussing the ability to access the joist supports to jack them up to level it later in life - because of the high water table (the house is right on Green Bay, and there is a swampy area right next to the shed), it would be foolish to expect it to stay level for 20+ years. 

What are thoughts on moisture with Flow Fill Vs the other options being mentioned here?

In reply to Adrian_Thompson (Forum Supporter) :

Flow fill usually doesn't have cement in it but the variation I'm talking about is pretty close in theory to mudcrete.

As for vapor barrier, usually I'd say no because flowfill has an absurd amount of water in it, think hundreds of gallons. This makes it flow easier and it "compacts" better. It taking a week to dry is very normal, pouring it on plastic will take exponentially longer. You'll have to weight plus /minuses there. If the water table is high enough that you are worried I'd probably do the plastic anyway. Just pour the flowfill in summer when it's hot and figure a week or 2 to dry.

No finishing at all, just a bit of raking in rubber boots ( the flat placer style rakes, not the garden ones). You could hire someone if you wanted but really......with enough water it's self leveling anyway. Running the chute is a skill but since it's just fill that doesn't have to be perfect you can do it yourself

I had a plywood floor in a 12' x 20' "tent" garage for years. I used plastic sheeting with 6" of  3/4" crushed stone on top of that. I put 2x4's on their flats on top of the stone for a frame to screw the plywood to. When I tore up the floor after 12 years the 2 x4's showed signs of serious bug damage and the bugs also got to one section of plywood but nothing else was in bad shape. With the cost of lumber right now this may not be the cheap way out but it should be effective for years. You could probably just spread some crushed stone on top of the dirt and make it a little shallower at the door end so you don't have a hump to get over going in. That could make a slope for water to drain towards the door. Unless you have a heated/air conditioned garage, I'm pretty sure moisture will happen. Temperature swings make everything sweat. 

Maybe I'm over thinking the moisture issue.  The camper currently lives outside under my in laws house on concrete.  I need to move it a couple of times a year due to flooding.  The sail boat sits outside under a tarp.  But in both cases there's ample airflow around to dry things out compared to a leaky canvas door.  Also I can't rule out buying an electric golf cart in the future too, and that would need to sit in there.

Thoughts