Hangar floor

[rocketman1988]

If you are considering a floor coating, make ABSOLUTELY certain that your concrete guy DOES NOT spray the concrete with a sealer. Many do, even if you request them not to...(ask me how I know).

Once that sealer is sprayed on, the only way to prep the surface properly for another coating is to grind the surface layer off...an acid etch won't do it.

If you choose to coat on top of the sealer, you can expect bubbles and peeling...

My plan is to have the concrete polished, like in the big box stores...never worry about peeling...

[ZachMiller]

I'm currently building a 1200sqft workshop, not a hangar, but here's what I've done.

I did a monopour of 4500psi concrete with 2' deep footers. 6" thick slab with 1/2" rebar, 16" OC. I have some heavy machinery, may get a larger VMC in the future, and may occasionally have a forklift on the slab, so I wanted real rebar. This might be overkill for "just a hangar", but you really only get one shot to pour the slab and the labor costs more than the materials (by a factor of about 3:1 I found, although my area has high contractor prices).

I'm planning on epoxy coating, 100% solids epoxy at about 10mils dft (I already have the material on hand and am planning to coat it this weekend). I had the contractor hand trowel the slab, then put a very faint brush finish on. No sealer. I will acid etch the slab tonight in preparation for the coating. I've ground slabs in the past for coating and it is no fun, so if you're going to coat plan for it right from the start.

I had the footers insulated vertically on the outside of the foundation (and 32" up the exterior walls with 2" EPS as there is an 18" stem wall along half the building). The slab is insulated 4' in from the edges underneath the concrete, but not the entire slab. 2" thick EPS is expensive and if you do the math the added insulation may never pay for itself, depending upon your climate. Most of your heat loss is around the edges anyway. The insulation and concrete was placed upon 4" of compacted base course. I had a 6mil PE vapor barrier placed on top of the base course and insulation. I was pretty cautious to keep it continuous and unpunctured, however the contractors put the rebar on chairs (as required by the city) and the chairs seemed to puncture the vapor barrier during the pour. They pumped the concrete in and the weight of the hose pushed the rebar and chairs right down. I honestly think the chairs were totally pointless and did more harm than good. I live in a very dry climate (northern NM), so I'm not too concerned, but if I were to do it again I might pay extra to have it pumped in with a crane. They might do that anyway for a building as big as you're building.

I live in a very mild climate, but its pretty cheap to put the in-floor piping in for radiant heat, even if you don't put a boiler in right away. I didn't bother, as a 18,000BTU minisplit will be more than adequate to heat/cool my space.

Zach

[TroyBranch]

If you decide to do rebar, (Way better than mesh) Place the insulation then use a measure wheel to layout the loop lengths. You can buy 300ft rolls so 280ft max but 250ft loop is better as mentioned. Spray paint the loop layout on the foam to confirm loop lengths. Use the plastic staples to fasten the tubes on the paint lines. Uponor is a great tube product. This method is much easier than trying to use tie wraps. Place the rebar on top of the tubes making sure the ends of the rebar is not near the tubes. The concrete placers do not care where they walk. More insulation is better than less. If you can get the molded insulation for the tube it is even easier. The tube just presses in, no ties or staples. In floor is the best heat.

If you want cheaper just use concrete and rebar on gravel with no insulation heated with radiant or forced air. Most building codes will not allow no insulation anymore though. You will definitely loose heat but that is how most people have done them for years to keep the construction costs down. If you will keep the hanger heated to a warm temp all the time, floor heat is the best.

If you just plan to crank it when you get there, floor heat is not going to work or save you much to cover the additional build costs from heat saving. You have to turn the floor heat up the day before to get the temp you want and the boiler will not be working in condensing mode as it heats up the space. It will be running at 100% for many hours.

[larryj]

Lots of good info preceeding me. I bought an existing condo hangar so was commited to electric heat. The thing I did that turned out to be great was that I doubled the calculated wattage by putting in 2 heaters; each sized for the application. The advantage is that it heats up faster on cold mornings.
As for finishes; +1 on the light color. I have done well over a dozen shop floors in my career and for my current hangar I'm going back to old school: thinned shop floor enamel to soak into the concrete. This will not give a super shiney beautiful floor but it should be practical. And when it wears just clean it real good and roll out a new coat. I've done all of the high-end stuff in the past and they all wear out, the thick epoxies and urethanes crack and chip, the stains just look junky, and sealer isn't bright. Anyway, that's my input :-)

[John Tierney]

A local A&P built a radiant heated floor that extended outside the hangar door a few feet to reduce snow/ice build up on the door/door skirt.

[Dantilla]

I'm about to begin construction of a new hangar, but will probably skip the heated floor.
While very efficient, and a nice, even heat with the thermal mass of the concrete, it heats and cools very slowly.

A house near me was used as a weekend get-away for a nice family, said they have to keep the heat on all Winter, as it takes a couple days to warm up.
Turn the heat on Friday afternoon, and it's not warm enough until it's time to leave on Sunday.

As long as I'm building the RV, I would leave the heat on. But if one is at the hangar only occasionally, a heated floor may not be optimal.

My current hangar has a gas-fired unit mounted up high.
In the coldest months, I kick the heat on, and go get a cup of coffee. Hangar is warm in an hour.

Still debating my options....

I really like being able to melt the snow in front of the bi-fold door.

[larrys]

Check out https://www.supplyhouse.com/ for buying the tubing. 1/2" radiant tube is fine.
Please from experience;
1. If you chose to insulate the floor do the whole floor - what you do not do will crack.
2. use 10x10x6x6 wire mesh and tie your tubes to the mesh. It make it much easier. Zip ties are cheep and easy. Do a perimeter zone of only a couple tubes around the outside. Then break up the interior in a couple zones and have all the tubing come up in one place.
3. Concrete 2800 psi 3.5" to 4" If you have experienced guys about 3 - 4 use 5" slump call when the truck is ordered. If less people or not experienced order 4" slump - this means how much water - or if you pour out a blob how tall is it (in a simple way to explain) also discuss when ordering and they will explain.
4. Either run grooves as you pour about 12' on center (or more) or the next day run a skill saw with a concrete blade cut the same pattern only about an inch down - make sure your tubing was low.
Have a good time, Larry

[abwaldal@gmail.com]

Having been in residential and commercial construction for 40 plus years and poured thousands of yard of concrete and hundreds of garage and house slab floors the one thing I would NEVER leave out is 6 mil BLACK plastic from under the slab. And don't let some idiot concrete sub tell you that you can't do it because we did it for 30+ years. Try not poke holes in it.
To me all the other stuff is good also but most people want to work in a room that is 60 or so degrees, so For me I would never put in-slab heating. Insulation is good. But if you put a thermometer in the ground a couple of feet and read the temperature is is about 52 degrees. Meaning that if you insulate the sides of the slab from the outside the floor is almost up to temperature.
As for fibermesh In the slab. I would never put it in an interior slab. To fuzzy. And of little use. We used it in a bunch of jobs and quit years ago be cause it didn't do the job rebar does. But rebar can cause cracking along the bar lines also. So if you do not want cracks use rebar and mesh.
The real question is how much ya gonna spend the stand on a floor for. Oh ya nobody is gonna pay you for the extra expense if you ever sell.
After 6 mil black visqueen the most important thing is to compact the ^@%
out of the sub grade.
Enjoy the experience. An additional benefit is with visqueen under the slab your cardboard boxes can sit on the floor and won't absorb moisture.
Art

[emsvitil]

Has anyone ever build a hangar with a basement?

Just thinking of all the stuff you could store under there.............

[Mhead]

Good advice here, especially from the contractors with years of experience. The plastic vapor barrier under the slab is key. I have a lot of experience with construction in the food industry. If you decide to put on an epoxy or other type topping, I recommend at least 28 days of curing before coating so it can expel moisture. If you top right away, the moisture has nowhere to go and will probably delaminate the topping. I like bare concrete where possible. "One less thing" as Forrest Gump said.