What is Water?
It’s a silly question, I know, but water is a strangely neutral and resounding chemical. Before I listed its molecular name, Dihydrogen Monoxide, named such as it has two hydrogen atoms and a single oxygen atom in its standard molecular form. Thanks to this, water is a dipole molecule and likes attracting other particles to itself, one of its favorite things to attract being itself.
Water is the neutral chemical on the pH scale; it’s neither acidic nor alkaline in its natural state. Water is also a natural solvent; many minerals dissolve in water to the point that instead of specifying “water-soluble,” often when a compound is mentioned to be soluble, it is assumed to be precisely in reference to the chemical.
With that, this resounding chemical born from combustion covers ~71% of the planet’s surface or anywhere from ~45 – 75% of the human body. But enough of its prevalence and nature, why is it so bad for architecture?
The Primary Threat is Erosion!
We all know what a river or a stream is, we all know that beaches have either shores or cliffs, and this is because, with time, water is good at scrubbing. It doesn’t need a sponge, just time and the elbow grease the moon puts in at hightide. Moving water is rather rough; you can imagine it as sandpaper or a metal grinder but less time-efficient. It can carve away at nearly any mineral put in its path, from solid stone to dirt, to gravel, to the walls of your home. Water is even used industrially for this purpose, ever hear of pressure washing?
While typically, erosion is spoken of in reference to the aforementioned examples, namely rivers and beaches, even rain is able to erode minerals. And unlike those examples, rain is free to land on anything and goes downwards with gravity, so it’s naturally effective against structures made by men. Another difference is that rain isn’t a consistent threat, it’s damages can be repaired at a similar if not faster rate depending on where as it comes and goes. But it along with it’s brethren rain, sleet, and snow, are in a unique position to use their vertical movement and freedom of position to erode whatever they please.
Indeed, rainwater carves down marvels of engineering the same way rivers carve out their paths through the soil, slow and steady. However, rainwater has other tricks on its sleeve to help speed up the process.
Material. Material. Material.
If you have taken the time to learn about the materials we humans have learned to manipulate for our shelters, a commonality will stand in what we have elected to stick with. They all have to deal with water, so we choose them based on their ability to withstand the liquid.
Often porous materials able to leak water intake back out naturally are chosen because water has another ability. It can freeze, and unlike most liquids, water expands when it freezes. This is because it is a polar molecule; when forming its solid form, the molecules prefer to keep a lattice structure; in laymen’s terms, water is a molecule with a magnetic field that has a clearly defined negative and positive regions, and when the molecules have to form a rigid structure as a solid they do so in a predictable fashion.
Back on track, rigid non-porous stones tend to crack over time, with water only aiding and abetting the process by running down its side in the form of rain. When water finds its way into these cracks and freezes, it expands, prying the cracks further and further open overtime till the material gives and breaks completely or is sufficiently weakened to collapse.
Porous materials avoid this by allowing some of the water in without the need to crack; however, if they cannot sufficiently drain it, these materials are wrought to the same fate when the water freezes within them and break them open. Porous materials with high resistance to erosion and naturally high rates of drainage are thusly the best.
Foundations are the Base.
This section has to do with the material, but not of the building: solubility, the ability to be dissolved. Water is a rather infamous solvent. If you ever wondered how cement just suddenly collapsed to give rise to cenotes or sinkholes, this is the answer.
Certain materials in the dirt beneath a home are dissolved away, loosening and weakening the soil till it collapses in upon itself. This process is known as the Karst Effect, with Karst being landforms made of limestone or another water-soluble material that erodes and dissolves away to form caves and caverns.
This can happen below buildings as well, causing landslides or sinkholes below them and the building to collapse in upon itself.
All Together Now
So, one home stands through thick and thin, faced with water eroding it, breaking it apart, and dissolving the very foundation it stands upon at the same time. It’s already a triple threat, as the erosion lets water in more readily, and that gives way to more cracking. And if, for any reason, a structure is built with water-soluble material, it is also dissolving away.
What of rust? Well, rust is not water damage specifically. It’s oxidation, and if you remember, water contains an oxygen molecule. Iron may rust, but silver tarnishes, and copper like Lady Liberty or a penny develops a patina. All of these are oxidation, and water is a prime oxidation agent. It’s a chemical reaction that creates oxides between the water, air, and material. Oxides do not tend to be as sturdy and often can have other hazardous effects. A famous example being rust and tetanus.
Precipitation: rain, snow, sleet, hail, blizzards, hurricanes, lightning storms. They all come down from on high; they carry with them their unique threat, Acids. As the water falls, it rids the air of carbon dioxide, nitrogen, and sulfur. This is good for many reasons, but these concoctions give birth to carbonic acid, sulfuric acid, and nitrogen; it’s just a mix of various acids. These acid rains are just as bad as they sound, adding only another layer of chemical weathering to the mix.
Water is fantastic; it gives us life and is vital to so many processes of the world. It’s everywhere, more abundant in the natural world than nearly anything else.
But that’s biology; when it comes to geology and architecture, it’s a menace.