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The long-term rental units will be 25 foot diameter domes. The design is by Monolithic Constructors and the particular type we are building are called their Ecoshell I. It consists of a poured concrete pad. Then, steel-reinforced concrete walls are constructed. Finally, the outside is covered with an elastomeric paint to waterproof the unit.

We decided to first construct a ten foot diameter dome to train the crew. This dome will become the guard station. It is located between the parking area and the main hotel building.

The first step to construct it is to clear and level the building area. Then, a trench is dug for the foundation. Two rings of 1/2" rebar are placed in the trench. The sides are formed using plywood, and a rebar grid is placed in the center to reinforce the floor.

Next, concrete is poured to form the floor and foundation. It is leveled even with the top of the plywood forms and L-shaped rebar is inserted into the wet cement shipping the area where any doors will be placed. The rebar stubs are doubled up on the sides of the door openings.

The next step consists of attaching the airform to the concrete. This is done by drilling holes in the concrete and bolting the airform down using one-foot long metal angles. The actual "bolts" are called Tapcon Screws—screws specifically designed to directly attach something to cement. They can be screwed in and, after the structure is done, unscrewed.

Of course, once everything is mostly attached you either need to decide to stay inside for a few days or crawl out through the access tube that Monolithic thoughtly provided.

Once everything is bolted down and sealed the access tube is closed off and the smaller air tube is connected to an inflator. The pressure needs to be maintained at 6-8 inches of water so we built a primitive pressure indicator. This is the beginning of the inflation process.

About a half an hour later, things looked like this. This was followed by a lot of speculation about what it looked like.

The next task was to start adding rebar. Raul decided it was not going to be easy trying to work on the top of a 10 foot diameter and 10 foot high air-pillow. So, starting with some trees that we removed for the main building location and/or trees that fell in the wind and a "rural precision board cutter" (chainsaw), the crew built the scaffold.

Next, the rebar ring was added at the top and they started adding the vertical rebar. After "guess bending" a few, they built a template so the bars could be pre-formed. Installation then just amounted to wiring them in place.

Here the horizontal rebar is in place. The space for the door and window have no rebar. Next is to put in a plywood form for the cement that will go around the door and window openings and put in more rebar.

Raul suggested adding chickenwire before putting on the concreate mix. Made sense to me so we did. This is what it looks like when he has put the first coat of concrete on it.

This is the dome after all the rough coats of concrete have been added. At this point it is time to wait for the concrete to cure and then we can take out the form.

This is the dome after the the form is removed. You can see in through the door and out through the window. Next step is to finish the inside cement to cover the rebar. Then a final coat on the outside with fine sand.

This is what the inside looks like. Ugly comes to mind. You can see the rebar grid but that was expected. Monday they start finishing the inside.

Here Raúl is putting a finish coat of "paster" on the outside of the ten foot dome. The concrete work is almost done.

Stay tuned for more information as the process progresses.

Dome FAQ

We get asked a lot of questions about the dome so we decided it was worth adding an FAQ section.

Is the plastic bag part of the building?

No. It is bolted down to the floor, inflated and used as a form. Once the outside is stuccoed, it is deflated and removed and the inside is stuccoed.

How thick are the walls?

They are from two to three inches thick. They are structurally fine at two inches.

Why a dome?

There are a lot of reasons. From a facility maintenance point of view, not having roofs to fix, rain gutters to clean out and such are pretty important when you are in a pine forest. From a construction point of view, we have one albañil (mason) and the rest of the crew are just laborers. That made it easy to assemble an all-Nicaraguan local crew. Finally, concrete and rebar are the typical construction materials here so they are a good fit.

What makes them waterproof>

Once the cement has had a chance to fully cure (3-6 months) the outside is painted with an elastomeric paint. It forms a thick, flexible covering.