There are many definitions for self-construction, also several types of it, but all of them can be considered as a form of social production of housing, that is, the promotion and at least a part of the construction is carried out by the inhabitants or users themselves, they participate in a direct and personal way, and moreover they do it without any profit motive in mind.
What is self-construction?
For simple products that do not require a project, for example, the construction of a high performance stove, self-construction would be similar to a training workshop, in which the interested party or parties participate in the execution of the small work; learning, putting in their own work force and accompanied at all times by our personnel. In this way they manage to learn knowledge about the execution of, in this case, a stove and also get an economic saving, since all the work done by the individual is work that does not have to be done by a professional for hire.
When it comes to self-construction, there are more limitations because it involves a series of functions that can only be carried out by qualified personnel, which are established in the Technical Building Code. They are the following:
– Creation of a basic project (architect).
– Realization of an execution project (architect)
– Direction of the project execution (technical architect)
– Quality control (technical architect)
– Health and safety coordination (architect, technical architect or specialized company).
Having said that, it is clear that the main function to be assumed by self-builders is that of a bricklayer and it is in the replacement of labour that the main economic saving lies. The second great advantage is that the developer is free, for our part, to hire people from his environment whom he trusts to do certain jobs. This also benefits people in their family or friendship circles.
In return, the self-builder, by intervening in the work in this way, also assumes responsibilities in the same terms that a construction company would do to third parties in case of an accident or a bad execution. In order to do so, he must also register with the Tax on Economic Activities as a constructor for the duration of the work. In practice, it would happen that you would share responsibilities proportionally with the technicians who assist you (architect, technical architect and health and safety coordinator)
At this point it should be stressed that we have always talked about the self-builder as a legal figure with the capacity to hire the people who are going to work with him. This is not the same as working with volunteers, which is prohibited by law and could only be done through a training activity as students; intervening in very low specialization jobs, in which they are exposed to very moderate risks and always covered by a civil liability insurance.
However, if self-construction is taken seriously and things are done right, there should be no problem and it should be an unforgettable experience of self-fulfilment and learning. The quality achieved can be equal to that achieved by professionals if very close and continuous advice is maintained with the technicians.
The earth, stone, cereal straw, wood, common cane and many more that continue to be rediscovered. In bio-construction it is essential to take into account the energy, both that which we generate and that which our house consumes. Therefore, not only is it important to have a sufficiently efficient home thanks to its design and construction systems, but it is also necessary to adapt the heating and/or cooling system to its particular conditions. Self-supply with renewable energies and save by reducing consumption with methods of use thanks to bioclimatic or high performance stoves.
ADVANTAGES OF BIO-CONSTRUCTION?
- They are healthy spaces because of the use of natural materials, without chemicals.
- The construction systems transpire, balancing the humidity between the interior and the exterior, avoiding condensation.
- Sustainable constructions, both in their construction and in their useful life.
- Materials are reused, so we contribute to the reduction of waste and at the same time save the environment and the customer the cost of new materials.
- Exclusive designs adapted to the needs.
Are ecological buildings cheaper than conventional ones?
It is widely believed that bio-construction is much cheaper than conventional construction, when in fact its initial cost is comparable to the latter. However, thanks to the possibility of taking advantage of the user´s resources in the design and construction of the project, savings of up to 40% of the total can be achieved.
There are no “buts” regarding energy consumption, where great savings are achieved. Bills start to decrease from day one due to the high energy efficiency and low consumption of bio-constructions.
Do the ecological buildings comply with all legal requirements?
Yes, although it may take a little longer for the administrative process to be completed if the technicians of the relevant town hall are not familiar with this form of construction. The Technical Building Code allows the project drafters to justify the construction systems they propose even if they are not described in that standard.
How long does it take to finish this type of construction?
It depends on the characteristics of each project since the construction systems are very varied and the possibility of self-construction is a very determining factor. However, it does take a little longer than a conventional construction because the construction process is more handcrafted.
Are the facilities different from those of a conventional home?
They don´t have to be. They can be executed as in a conventional construction although they can also incorporate, and we encourage them, renewable energy installations, green filters to purify waste water, rainwater collection systems, high performance stoves, etc. It depends on the tastes and possibilities of the interested party.
Do they need special maintenance?
Natural or traditional constructions do not need more maintenance than a conventional construction would have. Like everything else, they need regular maintenance for optimum conservation.
Do straw constructions burn easily?
Straw bullets, against all appearances, have good fire resistance. Once the construction is finished they are plastered with mud, which isolates them from the outside and does not allow oxygen to enter. The technical code requires a fire resistance of 30 minutes, while an unplastered straw bale wall has a fire resistance of 90 minutes.
How durable are natural buildings?
With proper maintenance they can last for many years, centuries. Examples of adobe and tapial houses abound in every village today. With regard to straw houses, the first ones made in the USA and Canada over a hundred years ago are still standing.
Is self-construction a great saving?
Self-build simply avoids paying the masons who would do the job for the self-builder and his helpers. But it also means more responsibility to the administration.
Can this type of construction only be carried out in rural areas?
They can be built in both rural and urban areas, always in accordance with the corresponding Municipal Urban Development Plan of each town.
Steps and costs in a conventional bioconstruction
In our intense, and less and less brief, experience dedicated to bioconstruction, we find quite a few people interested in carrying out an ecological construction, who when contacting us say that they want to make a house on a plot of land located in X place, and then ask us the cost. With this approach it is not possible to give a price, in any case a notion.
A construction is a more or less complex process, subject to multiple variables that make each work a completely different world from the others, even if the same construction systems are used. If, moreover, what we ask ourselves is a self-construction and/or bio-construction the matter becomes much more complicated.
People outside the world of construction are often unaware of the phases through which a project passes, the agents involved in it and the particular circumstances that can condition the final price of a project quite a bit, hence their claim to know an adjusted price with hardly any data provided.
In this part of the guide, we are going to introduce the main agents involved in any conventional project and the most important factors when evaluating it.
To explain this we will use a typical example of the following characteristics:
First of all let´s see the phases that a project must go through and who must carry them out:
1. Design phase:
1.1. Basic project and execution project: carried out by an architect in the case of housing projects. For smaller projects or with other use, it can occasionally be carried out by a technical architect or other type of engineer. In this phase it is necessary to work with a lot of understanding with the interested party, since it is necessary to shape his idea as faithfully as possible to the reality, limited by the legislation, the own versatility of the constructive systems and the economic capacity of the interested party.
The cost also depends on the workload involved. The volume of the project, the complexity, the changes… are the determining factors. Approximately, according to the current market, it is around 5% of the EMP.
1.2. Licences and permits: To obtain the provisional building permit, the basic project must be presented (previously approved by the competent professional association, for housing that of architects) to the Town Hall on duty. To obtain the definitive building permit, the execution project (also endorsed by the Association) must also be presented to the Town Hall. If the land where it will be built on is catalogued as rustic, it must also go through the corresponding delegation of your Autonomous Community.
These rates, like the construction tax, vary depending on the municipality and the characteristics of the project, as the rates are the result of applying a percentage to the cost of the project. Each administration applies the percentages it deems appropriate.
About 5% of the EMP
2. Execution phase:
2.1. Project management (site management, execution management, quality control and health and safety coordination of the work) In housing projects, the project management is the exclusive task of the architect, and the execution management, of the technical architect. The Coordination of security and health and the Control of quality can be made by both professionals indistinctly although normally it is carried out by the Technical Architect.
As with the drafting of the project, the cost depends on the volume of the project plus the visits to be made. Larger or more distant projects have higher costs.
Approximately 8% of the EMP, distributed among the different agents.
2.2. Construction company: it is in charge of assessing the Material Execution Budget (MEP) and carrying out the construction with its means. The cost depends directly on the characteristics of the construction: dimensions, quality of the materials, labour requirements, duration of the work, auxiliary means required…
The construction company will carry out the work according to the execution project and under the directives of the Project Management, which is the one that watches over the interests of the promoter and the control of the execution according to the project.
After all this explanation, we will go on to present some summarized budgets , of material execution of a construction company and of fees of the technicians, for our example house. To elaborate this example we have started from a cost per square meter built of 850 ?, an estimation based on the fact that the conventional costs are between 750 and 1100 ? per square meter and that our adopted qualities are “medium/rustic”.
Based on this PEM we calculate the fees of the technicians and the approximate costs of permits for our example house.
After this clear and daring presentation of data, we hope that it has served to better understand the phases of construction and we can only refer you to the next entry, where we will analyze, phase by phase, the different conditioning factors that can make us save substantial amounts thanks to bioconstruction and a different work methodology adapted to the individual needs of people.