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JohnD1956

Opinion on storage building floor

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I have a friend considering re-doing a barn floor specifically so he can rent storage space in the winter. Please take a moment and aadvise which is better for the cars: concrete or asphalt?

Thanks

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Benefits of AACA Membership.

Concrete is the hot ticket for indoor garage floors. With oil prices being what they are, concrete has become a lot more competitive (actually, asphalt has become a lot more expensive). I'm a fan of concrete just for durability's sake and the wide variety of finishes you can use. Some will say that concrete allows moisture to wick up through it, but a well-poured slab will have no problems. Modern houses don't often have standing water in their basements, do they?

Concrete is a lot tougher, too. You can put floor jacks and jack stands on a concrete floor while they'll sink into an asphalt floor. Concrete resists buckling better, too. Asphalt is always a little flexible so it can flex better when roots or frost heaves are underneath, but they'll eventually crack and have humps because of it. Concrete will resist the motion a lot longer, and if it has properly installed stress reliefs, won't heave and buckle in the middle of the slab.

As a petroleum product, asphalt will burn, which you might want to consider in an enclosed space used to store cars filled with other petroleum products. It isn't as resistant to dripping fluids as concrete, either. Certain automotive fluids will eat into it.

Also, a black asphalt floor in a garage will be REALLY dark.

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All of the above. The installation of underfloor insulation and a vapor barrier will keep your cars dry as a bone.

Concrete also gives you the option of using the slab as a thermal battery for a hydronic floor heating system. Embedding PEX tubing in the concrete allows for even heating at minimal cost. Systems can be built up using a water heater, circ pump. zone valve and thermostat.

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If you ask a cement contractor about installation of underfloor insulation and a vapor barrier he will hate you forever. It makes the concrete much slower to set up and he has to sit up all night before he can do the final finishing. Although it sounds like a very good idea, my contractor said it was not neccesary. I guess he wanted to get his sleep that night.

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True, but you'll end up with a much stronger floor. The longer concrete stays wet the harder it gets. If you don't use a vapor barrier the concrete will constantly wick water from underneath it.

A decent solution to that problem is to put the vapor barrier under about 4" of compacted stone or dry sand. Problem solved.

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Some good advice here....

I once had a barn with a dirt floor & it was really bad for storing or working on cars. Asphalt is not much better for all the reasons previously listed.

My shop has concrete with hydronic heat my son and I installed for about $350 with a used water heater PEX tubing and a little TACO recirculating pump.

I did have a problem with my concrete contractor who didn't know how long it would take to cure with the plastic vapor barrier I laid down under the hog wire & PEX tubing. Due to the longer cure time and freezing weather when poured, the surface spauled & required resurfacing. Barry noted the solution is to lay down a sand bed so the water can drain.

I used a light colored floor coating to eliminate dust and make it easy to clean up drips & spills. It sure brightened up my shop. If you want to store cars above freezing during the winter, go with hydronic heat too...

Concrete is the best way to go...no contest!

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I had a 1500 square foot garage floor poured last August and a 43 X 25 foot pad in front of the garage poured last November. The concrete guy I used said with the price of oil going up there are some jobs where concrete is cheaper than using asphalt.

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Yes, this is an 1850's barn. Can't say what was stored in it ages ago but the place has been resided, re-roofed, and made as weather tight as an 1850's barn can be.

The old floor in the lower level had broken up and it was removed. It's just awaiting a new floor now.

My friend does not partake in this hobby. He was thinking of this more as just winter storage for others. Basically park it and come back for it six months later. That's the usual schedule here in NY.

Looks like concrete is the way to go for this endeavor.

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Barry, the vapor barrier goes under the 4 inches of sand? Or over the 4 inches of sand?

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JohnD1956....Does he own the property or is he going to fix up someone elses' property in order to rent it at his own expense? As to the basic question "concrete or asphalt"; I would recommend concrete,fiber reinforced, 4+" thick approx. 7,000psi+/-.

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My 30 x 40 shop floor is concrete, with a single layer of 6-mil poly as a vapor barrier. As soon as the troweling was finished, we hosed as much water onto the surface as we could get to stay on it and covered it with another layer of 6-mil, seams taped. Left it on for 30 days to harden the concrete. The contractor had no problems whatever with our choices.

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I should also mention that the concrete is wire-mesh reinforced, the building is ventless-gas heated in the winter and a/c'd in the summer with year-round dehumidification. With good gutters and downspouts that strategically funnel rainwater away from the building, toward the away-slope of the land, I have had no cracking in its 9 years of life thus far.

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Guest BillP

I've done a few barns, both restore and new construction. Here's what I'd do on an old barn.

Make sure surface water from outside can't get in. A simple perimeter trench with perf pipe, backfilled with gravel and conducted away from the building will help. Also, run gutters around the roof edge and downpipes to carry away the water. Surprising how much water falls on a roof.

Inside, remove any loose organic stuff like old tree roots or what have you. These will eventually rot and cause weakness under the slab. Fill the holes and tamp down with crushed limestone, I use 304. Lay down heavy reinforced plastic film; if you're fussy, tape the edges. Spread and tamp a layer of sand; cheap, clean sand is OK, nothing fancy. Cut and fit 2" foam board to cover the sand. Nail a strip of homesote or similar around the wall where the slab will be. This will allow the slab to uncouple from the wall and float up and down through the seasons.

Cut and fit what the engineers call welded wire fabric; you can call it 4" wire mesh. I also throw in whatever else I have laying around like old rebar diagonally from the corners to reduce chance of cracking.

The WWF is supposed to be in the vertical center of the slab, that is, not floating on the top or laying on the bottom. You can monkey around and put bricks etc., under the mesh to hold it up but the best method is to pull it up through the wet concrete as you are finishing it. I use a hoe or garden rake. Look up the specs for good quality concrete and order it from the batch plant. In fact, go to the batch plant and talk with them about what you're doing. A few extra dollars in the mix to make it stronger is in my opinion worth it. I think the last slab I poured used 3000 lb concrete. Don't pour in the winter, they use antifreeze which weakens the concrete. They may offer hardeners, fiberglass or other admixtures that you can get if you have extra money. I don't so I don't.

When the truck arrives, ask to see the batch paperwork to match it up with what you ordered.

After you can walk on it, within 12 hours or so of the pour, snap chalk lines and saw cut control joints. These are to guide the concrete to crack along straight lines so you don't have a big jagged line running through the slab. You can caulk these later if you like, but that's mainly to keep little nuts and bolts from falling in while you're working on a car. Apply concrete curing compound; this retards moisture evaporation making a stronger slab, and it tends to make a better looking, not so dusty slab. It isn't stain or oil proof, so if you want that, you'll have to use something fancier.

If I was talking to a contractor that wouldn't do any of this stuff, I'd keep looking. Like a good paint job, a lot of a good job is in the preparation. Admittedly I'm describing a Cadillac job, but that's all I do. The job could be done cheaper, just expect it to look and perform cheap.

In an old barn, I'd spend some time making it weather and rodent tight. Nothing will irk your customers more than to get the car and find it full of mice. Traps, poison, those little electronic boxes, I use 'em all. The damn cats are indifferent to my instructions.

Barry's idea to paint it the color of dried blood is classic! laugh.gif

oops, not classic. vintage, maybe.

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<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: JohnD1956</div><div class="ubbcode-body">Barry, the vapor barrier goes under the 4 inches of sand? Or over the 4 inches of sand?

</div></div>

Under the sand. The mason can't really start work on buttering the surface until the concrete starts to set up. Allowing 4" of sand to absorb the water will allow a faster set-up and retain quite a bit of moisture for curing.

Once the concrete cures it will wick all the moisture out of the sand, leaving a perfectly dry and stable substrate.

I used crushed, compacted, limestone under mine.

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Thanks for the information Barry and everyone. I sent my frind a link to this thread so he can see the opinions and helpful hints you all posted.

Harry; my friend owns the place.

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Heated storage brings a premium in northern climates. If he does heat the floor, don't use the typical radiator loop like you would with electric heating cables. By the time the warm water gets to the end of the loop it's lost its heat, defeating the desired evenness of radiant heat. Due to the high ceiling of a barn, this is the most effective kind of heat.

The correct way is to use a serpentine loop. You start off making smaller and smaller circles, leaving a space in-between. When you get to the center you turn the tubing 180° and make your return loop in-between the previous coils. This will provide you with even heat distribution.

There's nothing better than a warm dry floor in the middle of a NY winter.

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