Materials
Materials for building an ecological house
In the design of a healthy and efficient home, the first step is the definition of basic bioclimatic design strategies. Even so, once the functioning at an efficiency level has been defined, the selection of materials for building an ecological house will be one of the keys to success.
One can opt to be a pure environmentalist and select only natural materials that respect the environment (bio-construction), or adapt the choice according to the budget and requirements of the project. It must always be kept in mind that the chosen materials must correctly fulfill their constructive function, even if they are not as sustainable. The reality is that although our studio favors a more purist approach, working only with natural and healthy materials in harmony with the environment, these materials are often more expensive. Although it pays off in the medium term in every sense, not all clients are willing to sacrifice square meters of living space in favor of healthier materials.
It is very important that, whatever the choice, the options offered by each material are well assessed. One must consider the availability and local origin—or lack thereof—of the material, the lead times, its price, and the characteristics, advantages, and disadvantages it may provide.
The best approach is to establish limits while always aiming to build in an ecological and healthy way, respecting the environment without this commitment raising the budget to impossible levels. Therefore, the objective of this article is to guide you through the vast world of construction materials, differentiate between those that are more or less recommended, identify which are more or less ‘eco’, and explain why it is important to choose sustainable and healthy materials that will provide your home with extra health and harmony with the surroundings.
The article begins with a prior definition of the particularities of bio-construction, starting with materials that are suitable according to bio-construction guidelines (building in harmony with people and the environment). Next, the most common materials for building an ecological house will be discussed, separating those used for the structural part and enclosures, insulation, piping, cladding, flooring, and paint and varnish finishes. Finally, the selection criteria to be considered will be discussed, serving as the best guide when making a final decision.
If you still have doubts after reading this, remember that this firm specializes in ecological architecture. Do not hesitate to ask for guidance on the best choice of materials for building an ecological house.
Materials for building an ecological house according to bio-construction criteria
In the introduction, the term Bio-construction was mentioned briefly. This concept is defined as any architecture executed in harmony with people and the natural environment.
The development of the construction industry, focused on doing things faster and cheaper, has led to an increase in the use of materials that are polluting and harmful to health. This prevents homes from breathing or involves petroleum derivatives, to the point of using materials with recognized carcinogenic components that are released into the indoor air of our homes. Consequently, as in many other fields, advocates for healthy, toxin-free homes have emerged in recent years, using materials that are harmless to the environment throughout their manufacturing and use. This idea seems very simple to define but is difficult to put into practice, as unfortunately, polluting or intoxicating is free, and materials with a high ecological footprint or high toxic content are still much cheaper than natural materials that respect the environment and people.
To give an example, the cheapest insulation in construction is a petroleum derivative that does not breathe, but with very little thickness, it achieves high efficiency at a very low cost. Furthermore, being a plastic, it is water-resistant. This is expanded polystyrene or XPS.
As an alternative, there is the option of insulating a house with natural insulation based on wood fiber. This requires a significant thickness, cannot get wet, and its cost is much higher than XPS.
Given the current state of the market, it is necessary for both professionals and clients to generate an increasing demand for healthier and more natural materials for building an ecological house to allow the bio-construction industry to develop and become more affordable. Unfortunately, budgets are often too tight or clients want to achieve the maximum square footage at the minimum cost. This is why the execution of ecological houses does not always allow for strict adherence to the material selection criteria of bio-construction.
Most common materials for building an ecological house and their characteristics
That said, this article attempts to define those materials that are most common due to their quality-price ratio and which, although not all meet the criteria of harmlessness, health, and respect for the environment, achieve a good balance or have a reduced ecological footprint.
Summary table
Structure and enclosures
Starting at the beginning; the structure and enclosures are the skeleton and skin of any house, and therefore they should last a lifetime. They are the most permanent elements and those that must withstand the most in a home. You may wonder: Are there materials for building an ecological house that support these conditions? Indeed there are!
There are a good number of natural and healthy materials that offer strength and durability, so we can use them to build the structural parts and enclosures of our home. Among these materials, we highlight everything from earth blocks and bricks, concrete, rammed earth, adobes, etc., to wood elements and natural stone.
Firstly, concrete blocks, although they do not meet all bio-construction criteria, are worth considering for their availability and economy. They are also a good structural option that can be applied in many different situations. Their composition is based on a mixture of concrete and mortar that sets in standardized molds until fully dry. To lighten their load and save on material—and therefore cost—they are usually hollowed out inside, always ensuring they support the relevant load. In some cases, they can be reinforced with steel rebar inside.
Fired earth bricks offer great mechanical capacity to resist weight, in addition to their good insulating capacity. Thanks to their own weight, earth brick walls store heat very well, being able to release it several hours later when the temperature drops—this is known as thermal inertia. Finally, earth brick regulates humidity naturally, thereby stabilizing the indoor environment.
On the other hand, there is a slightly more economical option; conventional ceramic bricks, whether solid or perforated, follow the functional characteristics of fired earth, namely, great mechanical capacity. They are recommended for the construction of load-bearing walls, although in ecological terms they are not the most advisable as they require a large amount of energy for their manufacture, which entails a high contribution of CO2 to the atmosphere.
Likewise, Termoarcilla (thermal clay) is an innovative material. It is considered a low-density ceramic block with thermal and acoustic insulation properties that guarantee energy savings in the home. It is achieved with a mixture of clay and lightening additives that give the block homogeneous porosity. The result: a porous material that allows the surfaces of a building to breathe and indoor humidity to dissipate. In addition to benefiting its occupants, this material prevents the deterioration of the building structure itself and reduces the risk of rot in other materials by absorbing excess moisture. Finally, it contributes to sound absorption, functioning as an acoustic insulator.
Wood is a material that offers versatility, strength, lightness and, being hygroscopic, contributes to regulating humidity naturally. It has a wide variety of construction options, always being dry or workshop-based, making it much faster than building with a concrete structure. In Spain, there was no tradition of wood construction, but the growing demand for more efficient and healthy houses at low cost has led to the development of the wood construction industry, whether of local origin or manufactured abroad (generally in Eastern Europe).
Finally, stone is also a historic construction material, although it is considered a material for exceptional use due to its high current cost and the need for specialized labor for its installation. Its main characteristic is its great capacity to support loads, but furthermore, it does not require a large investment in terms of maintenance and has a long service life due to its resistance. At a structural level, stone works very well under compression, but being heavy, it is not usually used in floor slabs or roofs. In these cases, it can be combined with wooden beams or some other material that works well under tension.
Insulation
The next topic to address is the world of thermal insulation, one of the invisible protagonists of sustainable architecture: Insulation is responsible for protecting and isolating our house from outdoor weather conditions. It is of crucial importance for the indoor environment, as well as for regulating the temperature and humidity of our home.
Although, as mentioned, sometimes for reasons of cost reduction there is no choice but to opt for petroleum-derived insulation—coming from chemical processes—today’s article will only deal with natural and healthy insulation. Among them, cork, hemp, cellulose, cotton, straw, coconut, and expanded clay stand out.
The first of all, cork, is obtained from the bark of the cork oak and it is not necessary to fell the tree to obtain it. Therefore, it is considered a renewable resource that respects its environment. It can be found in panels or in granulated form. It is the most expensive insulation since its procurement process is very slow—one bark every ten years per tree—however, its characteristics are unmatched; it is the only natural insulation resistant to moisture, with great insulating capacity and conformable into self-supporting panels that can be used in roofs, walls, and in contact with the ground.
On the other hand, flax and hemp are two materials that come from easily cultivated plants and whose insulating properties are being increasingly exploited in construction.
Thirdly, cellulose is a fully recycled material, coming from paper waste. Not much energy is needed for its production and, despite its lightness, it has a good insulating capacity. Conversely, it is a material that does not resist contact with water and can be attacked by animals or insects, so walls insulated with cellulose must be very airtight.
Straw and coconut are materials that are gaining ground in the natural construction market, and both are materials with a small ecological footprint that require little energy for their production. Straw can be used as insulation by mixing it with mortar. Generally, the most common form is as insulation combined with a wooden structure. The main disadvantage is that it rots with moisture, so it is important to protect it very well in this regard.
And yes, coconut is another material for building an ecological house that can be used as insulation. The insulation is obtained from the fibers of the husks, following minimal extraction processes and without the need for additives. The result: an odorless fiber with good performance as thermal and acoustic insulation that is also highly resistant to rot.
Cladding
When a building or surface is clad, what is done is adding a new layer, covering it, either to improve its thermal capacities or simply for aesthetic reasons. Two types of cladding are distinguished: so-called hard cladding and amorphous cladding.
Firstly, hard claddings can be natural but are not strictly renewable as they require the exploitation of quarries or deposits. Stone or ceramics are some examples, as well as wood, whose maintenance must be more constant to keep it in good condition.
Secondly, amorphous claddings are those that adapt to the shape of the element they cover, thus being applicable anywhere. Clay mortars obtained from a mixture of sands and clays without additives have a positive impact on our health thanks to their hygroscopic capacity, regulating humidity naturally. At the same time, they have a certain capacity to insulate from noise and sudden changes in temperature.
Another type of mortar is gypsum mortar, whose mixture is produced with sand, gypsum, and water. Its final aesthetic is the same as that of gypsum but with greater fire resistance.
Finally, there are two very similar types of lime, obtained through lime, sand, and water. These are hydraulic lime and fat lime. Both are applied like mortars, but their main difference is that the former hardens with water while the latter does so upon contact with air. As they are products made from natural limes and sands, neither of the two limes contains additives or toxic particles that could harm our health. They are a good choice among materials for building an ecological house.
Water piping
Water piping is a world of its own, but it should not be sidelined because, after all, these are the conduits that allow the supply of water for cooking, drinking, showering, etc. Whether one likes it or not, many public pipes are made of materials that can leave residues harmful to our bodies. It is recommended, therefore, that in addition to consciously selecting the material for our piping, we consider installing filters at certain points depending on the intended use of the water.
The market offers a wide range of materials for the water piping of our homes, but many of the options are not recommended as they can be harmful to our health by containing toxic particles. PVC, for example, emanates vinyl chloride, a carcinogenic substance. It is also a non-biodegradable material and harmful to the environment.
First of all, for conducting clean water, there is high-density polyethylene and polybutylene, two excellent materials for these conduits. The first, high-density polyethylene, is a thermoplastic polymer made up of different ethylene units—in common terms, an organic chemical compound—it can be recycled! It is also light, flexible, and has high chemical and thermal resistance. It perfectly withstands water at temperatures of 60-100°C and cannot be attacked by chemicals.
For its part, polybutylene is another material for building an ecological house advisable for clean water conduction. It is also a thermoplastic material (it becomes moldable with heat and hardens upon cooling), has great flexibility, and high chemical resistance. In this case, it is a smooth material, which reduces pressure losses of the water circulating through the pipes, and it is very difficult for scale or calcification to deposit. It resists temperatures between -15°C and 95°C.
Rainwater downpipes are another matter. For them, there are more material options since the channeled water is not for human consumption. Downpipes made of ceramic, polyethylene, polypropylene, etc., can be found. In all cases, it is important that the downpipes have very smooth surfaces to avoid calcification or scaling. Finally, the option of galvanized steel downpipes should be mentioned, as due to their high resistance to physical stress and the protection provided by the galvanizing process, they are gaining more and more ground in the construction world.
Finally, drains. The market again proposes infinite possibilities in terms of materials, but if we take into account the ecological and healthy requirements defended in this blog, the most recommended are copper and polypropylene.
Copper pipes are very durable and safe, but they can also be relatively expensive. In their favor, they are very long-lasting because copper does not corrode. It is also fire-resistant. As for polypropylene, in addition to the advantages already mentioned, it is smooth and reduces friction noise, and it insulates heat quite well.
Floors
Now it is time to resolve the question of which materials for building an ecological house are most suitable regarding the flooring of our home. There is a great variety and field of choice in this area, but this article will provide a brief review of the most suitable options for building an ecological house.
The first material to be discussed is terracotta. It is a natural and ecological material composed of clay. Generally, it is placed in the form of tiles when used as flooring; in this way, it offers the client a wide variety of aesthetic finishes to work with.
Next, two options for continuous flooring: the first based on mortar (binders, sand, and water) and the second on concrete. Continuous mortar floors are characterized by offering very good mechanical resistance—to impacts and/or weight—and durability. The installation system is simple and economical.
There is currently a variant of this system that uses a self-leveling mortar, that is, with additives that make the mortar itself flat. Despite having a very similar aesthetic, continuous concrete floors are distinguished by needing expansion joints every 5 meters at most, to avoid cracks in the pavement due to material expansion caused by temperature changes. Another difference compared to its mortar counterpart is that concrete is NOT an ecological material and contains certain harmful or toxic components.
Turning again to the versatile wood, there are three different types of wood installation for floors in the field of paving. It is precisely these systems that help us distinguish and classify the characteristics offered by each of them, regardless of the type of wood used.
The first system would be glued wood. As the name indicates, the flooring is placed over a horizontally leveled layer using special glues or self-leveling mortar. The second system, and perhaps the most used today, is floating floors. In this case, the wood slats are placed over insulation or some elastic element and fitted together by undulations on their edges. It is considered an effective, quick-to-assemble, and economical system.
Finally, the floorboard system uses a sub-structure in the form of battens to raise the wood slats. An extra advantage of this system is that, by raising the floor, an air chamber is generated between the slab and the flooring, which contributes to a better acoustic sensation.
In addition to wood, bamboo exists as an alternative; it achieves a quite similar appearance and is considered more ecological: its manufacturing process has zero emissions, it is an antistatic and anti-allergenic product, and it has a hardness and density similar to that of tropical woods. Furthermore, bamboo is a plant that grows very quickly, so it is highly available and fully renewable.
Finally, we have the option of more traditional floors, whether stone floors or ceramic floors. The former is obtained from rocks, so it must not be forgotten that it is not renewable. It does not regenerate over time! They are normally used as outdoor floors since they are water-resistant, can support large loads, and are not very slippery. For an ecological house, it is rather advisable to opt for alternatives such as tiles or pavers, which are more adaptable in terms of size and come in a wide variety of colors, shapes, and layouts.
Ceramic floors, while natural, are not as ecological an alternative as wood might be, as they consume a lot in their procurement. They stand out for their economy since they have an affordable price, without losing strength and durability. They also have a wide range of finishes and shapes that can be placed in any room.
Paints and varnishes
To complete this brainstorming of materials for building an ecological house, it is worth addressing the field of paints and varnishes that can be used in a home. There are paints, varnishes, oils, and waxes that respect the environment, as well as the indoor atmosphere of the house and our health.
Normally, the most used paints in the construction world are plastic ones that contain products and particles harmful to our health and that diminish or limit the breathability of the wall—that is, the absorption and release of moisture, so important for maintaining a healthy indoor environment. As an alternative, there are silicate and lime paints. They are permeable to water vapor, they breathe, and because they are made from inorganic components, they prevent the appearance of microorganisms such as algae and mold. They have long durability that saves resources, and their composition is free of harmful substances. These are paints whose main base is mineral raw materials, a fact that results in significant respect for the environment both in their manufacturing process and their final effect.
As for the varnishes used in the world of bio-construction, they have an appearance and application very similar to conventional petrochemical products, but they can greatly improve the quality of the finish. Primarily, linseed oil varnishes are used, which have excellent qualities as a protector. It is breathable and waterproof, in addition to protecting the wood from insect attacks, always in a natural way. It is also considered a protector against ultraviolet rays when the wood is exposed to the sun and does not oxidize iron.
The function of natural oils for wood is also to protect it against the sun, insects, and fungi. Likewise, we can use them to beautify its surface while respecting its natural grain. It is important to apply natural oils based on linseed, castor, and wood oil itself, all of them coming from the seeds of different trees.
Waxes are applied for a surface finish. They generally serve to give the wood a more natural appearance. There are waxes of vegetable origin (carnauba wax), animal origin (beeswax), or even mineral origin (lignite wax or paraffin).
Selection criteria
Once the materials available on the market have been presented, it is interesting to establish criteria for choosing them following the foundations of sustainable and ecological construction. These would be: their proximity or local origin, that the extraction systems are as respectful as possible, that handling is minimal, and finally the material’s own characteristics.
Proximity – Working with local materials and companies. Costs are reduced and the local economy is favored.
Besides favoring the local economy, when choosing nearby materials, the energy and resources destined for their transport are directly reduced.
Respectful extraction
For a material to be environmentally friendly, it is important to start by analyzing its origin. That is, that the processes carried out during the procurement and extraction of the material interfere minimally with the environment, thus allowing for its renewal.
For example, if the environmental impact between stone extraction in large quarries is compared with the harvesting of cork oak bark to obtain cork, it will be seen how the former has very negative and costly consequences for the environment. In the second case, the material is extracted respectfully, as it is not necessary to fell the tree nor is any damage caused when removing the bark. Likewise, in the timber industry, there are entities that ensure certification that the wood comes from controlled operations and that felling is carried out respectfully.
Minimal handling
Once the raw material is available, the next step is to adapt and transform it so that it is suitable for construction. In any case, the less transformation it undergoes, the better it will be for the environment, since all processes generate emissions and waste and usually consume a lot of energy.
Rock wool, for example, is a material sold to us supposedly as natural. Well, the truth is that the manufacturing process of this material requires high-temperature furnaces to melt the rock, which consume a lot of energy. Furthermore, the obtained rock shavings are agglomerated using formaldehyde, a compound defined as carcinogenic by the WHO that can easily reach the lungs.
Characteristics of the material itself – Natural or recycled origin. Easily recyclable. Biocompatible.
The characteristics of the materials for building an ecological house are also important. They must be well understood to work correctly with each material and make good decisions.
Materials for building an ecological house will have to be natural, that is, coming from renewable and abundant resources. The most suitable are those that do not contain toxic particles or components that can cause damage to our bodies. Although recyclability is a property that not all materials have, it must be kept in mind. It is about avoiding materials whose environmental impact at the end of their useful life is high. Therefore, it is highly recommended to opt for easily recyclable materials.
Following the same line, there is a wide range of recycled materials on the market useful for construction. One should not think that by choosing such a material, performance will be lost. On the contrary; a recycled material provides the same guarantees as one fresh from the factory.
Finally, biocompatible materials cannot be overlooked. These are materials that do not contain toxic particles or chemical substances that can reach our bodies once installed at home. They are usually of natural origin and minimally transformed. Wood, stone, or some types of ceramics are examples of biocompatible materials.
As you will see, choosing materials for building an ecological house is very important and equally complicated due to the wide range available on the market. Paying attention to the origin and composition of what we choose is essential. Furthermore, we must not forget that it is not just about looking for environmentally friendly materials but also those that are healthier and contribute to improving the comfort of our home.
For this reason, it is also highly recommended to contact experts who are in continuous contact with this market. At Slow Studio, we work with natural materials in every project and build healthy and efficient houses for all budgets.
Do not hesitate to consult us if you have any questions about materials for building an ecological house.