Build an underground shop - why not?

[jinman]

I've been plotting and planning to build a nice 40 x 60 metal building for a long time. As I was excavating in my sandpit recently, I suddenly had an epiphany moment and realized I have the perfect place for a very large underground structure. I've included a picture of the site. I was thinking of making a pond in this location, but lately I've begun to think about drainage and how large a runoff I can provide for normal annual rainfall. I don't think I can direct enough runoff to keep two ponds full.

In the first picture below, the sandpit I've been using is in the foreground. The area with the deep gully and mounds at the top would be a single pond and my underground shop would face toward that pond so that the approach and front of the shop would have a nice full view of the pond.

In the second picture, the view is reversed from the bottom of the pit looking up. At the back and sides of the excavation, I have sloping ground that goes from 20' deep down to about 12' deep. My feeling is that I can build a shop back into this hillside with a 12' ceiling and columns inside for supporting the roof which will be covered with dirt.

I took measurements and I can easily fit an 80' x 60' structure underground in this area. I think I'd probably go 80' x 40' or maybe 80' x 50' with three rollup doors and one walk-in door on the front side. I might also build a concrete tunnel back to my house so we can use this as a storm shelter and also an underground cellar. My feeling is that I can use solar tubes for lighting and have a structure that's warm in winter and cool in the summer with very little heating/cooling costs. Ground water and seepage will be easily controlled since this soil is very dry.

So, does anyone have any experience with a structure like this? I know PatrickG built an underground section on his new house in Oklahoma, but I don't want anything as nice as a living area. This can be painted concrete walls and ceiling; very little finish work. I can even run electricity, plumbing, and compressed air in hanging channels. I'm not sure what kind of columns or the number required to put 4000 sq ft under an earth roof, but of course a shop is best with as much open space as possible. I believe a 12' ceiling will be plenty for any equipment I might want to put inside.

So if anyone can help me with experience or suggestions, I'm very open to all advice. I talked to my wife about this and she is very supportive. I don't think she wants a large shop blocking her view. She'd love to have this underground shop instead.

 

[EddieWalker]

Jim,

I'd love to see you do it just because of how unique and complicated it would be. But I'd have to caution you that it will be allot more money then building a metal shop on a flat concrete pad. While the concrete footings to support the walls and the concrete for the walls will be allot more money, the place that will really add to the price will be a roof capable of supporting the load of a dirt roof.

With a standard price of a metal building, I'd guess that you triple that price going underground.

Eddie

 

[mikim]

$$$$$$$$$$$$ but too cool! I'm betting you'd be looking at an arched concrete roof. You might do a search for earth builders in the area.

 

[jinman]

$$$$$$$$$$$$ but too cool! I'm betting you'd be looking at an arched concrete roof. You might do a search for earth builders in the area.

Did you have to use so many $ signs?

Yeah, maybe like a monolithic dome. The roof is what has me worried the most and what will drive the price way up. I would probably cut the costs immensely if I made three walls surrounded by dirt and the roof made of steel supports with normal sheetmetal. If I want to put in some type of hoist supported by the roof, it will be even more. It just seems to be such a waste to start filling in the excavation that Mother Nature provided me. Building an energy efficient earth sheltered shop also seems to have a long-term payback. The "cool" factor Eddie mentioned is also kinda appealing.

 

[Egon]

Do you want the roof covered in dirt too?

 

[CurlyDave]

Covering the roof with dirt will mean that you will probably have pillars or posts inside to hold the weight. You can probably get a much larger clear span with more conventional construction.

 

[jinman]

Do you want the roof covered in dirt too?

Egon and Dave, I sure would like to cover the roof with dirt and make it earth sheltered, but cost may prohibit that. I might have to settle for bermed construction where only three sides are covered with a conventional roof.

 

[6sunset6]

I have seen precast concrete roof structures backfilled with foam blocks and then some dirt. I think they will carry the weight fine. It's the cost that might be an issue. Call some precast guys.
It would be a great building.

 

[RobS]

It sounds very interesting Jim. Not sure about Texas, but up here in the midwest we would be concerned about humidity in an underground space. Even common basements up here get moisture/mold/rust in the summer without dehumidification. No way would I put a bunch of metal tools in an underground space unless it was properly conditioned. But again, things may be different down your way.

 

[johnnydel29]

My dad was a mason contractor for 41 years and I worked w/ him growing up. We did a lot of concrete work (too much).

The concrete w/ reinforced steel would be incredibly expensive, especially the labor. If you want to be safe, It would also need to be professionaly design by a licensed engineer - another big expense. However, it can also act as an awesome undergrown bunker that you can use during storms or a nuclear attack.

Awesome idea.

 

[czechsonofagun]

Could you piece it together from existing blocks? Like, say, bridge beams or such? I am sure somebody somewhere makes something usable.

I have a friend in Prague, his house building lot came with an old street car or tramway as we say, truck load of concrete railroad ties and 60 concrete factory posts. Posts look like steel beam with a ledge for the hoist rail if you ever seen one.

He tried to get rid of it, but it was too expensive - soo he rented a crane and with the help of 5 of us and a keg of pilsner urquel we built walk out basement from those concrete pieces. Some places it had to be formed with concrete added - but most of it was pieced together.

 

[Egon]

pilsner urquel

Only one keg?

 

[czechsonofagun]

Only one keg?

We had few dozens of these also. I believe you can get them in Canada.

 

[dfkrug]

I've been plotting and planning to build a nice 40 x 60 metal building for a long time. As I was excavating in my sandpit recently, I suddenly had an epiphany moment and realized I have the perfect place for a very large underground structure.

By all means, do it, JIN!

I does seem that a good deal of your excavation is done.

You can have your walls assembled and poured using ICFs (insulating
concrete forms) for about $3-4/sf of wall area by experienced contractors.
That includes labor and materials, waterproofed, but the footers and
slab are not included in that.

I have designed and built several of these kind of buildings (incl my house and
workshop and water tank), but I have only recently done a flat concrete roof.
It has a clear span of 20 feet and I designed for 100psf live load. Stamped
and stained. Two walls retain 8-10' of dirt.

My house has a wood I-joist roof rafter system with 14' rear retaining walls.
If I did it over, I would go with some kind of concrete insulated roof, like
PanelDeck or equivalent. Insulating conc roof systems are VERY expensive,
so I would prob not use it for a workshop-type building.

For your building, I would go with a sloped or domed roof. I did a domed
roof of only 4-4.5" thickness over my water tank: clear span 12.5'.

 

[hunterridgefarm]

Jim,

I think that would make a great energy efficient workshop/building. Hope it becomes a reality for you. Would love to see the project documented. Check on some government tax breaks for energy efficient structures.


Oh...that epiphany stuff, have them all the time...wife tells me to take a couple of Tylenol

 

[SamWalton]

You may want to speak with Jay Schafe of Terra-dome.com. He builds three different size super structures. The largest is a 40 foot by what ever you desire. Prefect for your application and the roof can handle a massive load of soil or equipment.

 

[yooperdave]

Precast Concrete is great - but expensive.

You will also need a waterproof membrane with a wearing surface over that.

Good Luck

Yooper Dave

 

[Max2310]

Before you get too exited with this, you might want to check your city rules...

 

[SamWalton]

Precast Concrete is great - but expensive.

You will also need a waterproof membrane with a wearing surface over that.

Good Luck

Yooper Dave

The Terra-dome system is not precast and is very affordable. You can make you concrete water proof with a 2 dollar per yard additive.

 

[EddieWalker]

I saw a show where they build concrete dome homes by blowing up a giant balloon type material. Then they sprayed concrete over it with rebar tied together. It was a big project, with allot of man hours, but when the concrete dried, they had a dome. I doubt it would be strong enough to hold dirt over the top of it, but then again, maybe....

Of course, how much per square foot are you willing to pay?

Eddie