Sand as a building material is virtually any granular material.

In soil mechanics, it is mineral-based material 0.074mm – 4.75mm in size.

So, the soil mechanics definition is more precise than the building material definition.

The principal material used in its construction was stone. While documents agree that the stone was quarried locally I’ve never seen anything that was able to identify the type of stone.

If you’re not familiar with stone construction it is very similar to brick masonry construction. The stone is shaped and put in place with a mortar to secure it in place. In some locations where the joints would be too large, the pieces would be locked into place by other shaped pieces like a puzzle.

Minor floors were constructed of timber beams with plank flooring.

Many of the walls that aren’t stone were plastered.

The roof has changed over time. Originally the roof was probably rolled or beaten copper, but it has seen replacements of lead and tern sheets. My understanding is that it is almost completely copper today.

A lot of structural improvements have occurred throughout the years such as additional buttresses but wrought iron bars and chains were added throughout the structure to keep it from shifting.

I have a feeling that I may have gone too far in my description already, and will stop at this point.

Unless there is a water tank or booster pump you are going to loose about 0.4 psi per foot vertical. Given that most floors are about 10ft floor-to-floor that is 4 psi loss.

So, if a first floor unit has 30 psi water pressure, the fourth floor unit has about 12 psi water pressure if no compensation system is in place.

Yes, though it might depend on the definition you’re using for levitation.

We float a structure on a liquid like a boat, but I don’t think this is what you mean.

Or in a gas like a balloon, but again this requires huge gas bags for buoyancy which will quickly limit your weight.

Magnets and electromagnets would require unbelievable amounts of power to levitate more than a fraction of an inch.

This leaves us with some “non-visible” force applying material like a gas jet or jet engine. Again, the power requirement is massive compared with the result.

After all this, this is why it isn’t really sought after beyond optical tricks to make things look like they levitate.

Short answer; temperature.

Air is largely affected by temperature, which causes hotter air to rise above colder air. The sun is always heating a portion of the Earth, but not others, creating a hot spot which change the air temperature.

Next major item is humidity or moisture content. the more water vapor present the heavier the air (which pushes it downward), but it can be heated more with less sunlight or other form of energy.

Next, we have height. Air near land has higher pressure than air at high altitudes. Which means air near the surface of the planet can more easily retain heat and air at high altitudes shed heat more quickly. This also causes dynamic of flows of differing densities, but that is likely outside the topic.

Lastly, we have obstacles such as mountains, trees, and buildings. As air passes around objects it changes the speed and denisty of the air, subject to the shape of the object.

After all of this you get gusts of wind, wind storms, or no wind at all. The mapping of, and predicting of wind is amongst the most sophisticated sciences we have today as it requires knowing as much of the conditions across the Earth and the things that may change those conditions. And you can see from the weather reports how often we get it right and how often we get it wrong.

First, let’s assume you can’t change your roof in any significant way.

You are looking for an element called a rain diverter. Basically, this is an ‘L’ shaped piece of flashing attached under the trailer edge of your roof tiles/shakes/slats. In most cases it only needs to be 1.5″ to 2″ high to catch the water. In smoother roofs, such as asphalt shingle, it helps to angle it towards your discharge point.

Snow guards are a little different. They look basically the same but are heavier due to the weight of the snow. Some areas also have rows of them to catch the snow to keep it from falling off in a small avalanche. Keep in mind that if you do decide to go with a snow catching strategy you need to check that the roof section can actually hold that kind of weight.

In the US the overwhelming amount of houses are constructed of light frame timber (2×4 or 2×6) then surfaced with either a cementous product like stucco or wood siding of some form. Larger homes and multi-family buildings used to be constructed of brick but modern larger homes and multi-families tend towards wood framing. Multi-families become concrete and steel frame once they go above five stories. Individual houses can be made of heavy timber light, heavy steel, concrete masonry or more exotic materials, but these tend to make up far less than 1% of the constructed houses.

In a vacuum they would stay together as long as there is no spin.

In an atmosphere it would depend on the shape and placement of each object. A non-aerodynamic front object or overlapping second object would find the air pressure forcing the two apart.

Firstly, you don’t want organic material in your concrete. It will weaken and discolor your concrete. There are mixes that support organics, but they are expensive along with requiring special equipment and knowledge.

That said, use about 60% gravel to 40% sand. This will get you close to a “well graded” mix. One part cement to 6 parts gravel/sand mix. Add just enough water to be workable. You can alter the amounts by a fair amount, but this is pretty close to traditional mixes.

The resulting formation tells you the frequency, rate, and material of the specific eruptions. Basically, both versions are possible, but the forementioned determines which you get.