Do I need an architect’s project to build a prefabricated house?

Whenever a house is built or an extension of a house is carried out, it must be built under the supervision and approval of a competent technician, that is, an Architect. Are prefabricated houses an exception? No. Although constructively they are different, with respect to the law they are the same as a house built by traditional methods.

How can I know if I can extend a building?

It depends fundamentally on the urban regulations and the pre-existing structure. Urban planning regulations limit how many square meters of roof can be built on a plot, what shape and height it must have. Therefore, if the capacity to grow has been exhausted urbanistically or has been exceeded in some way, it will not be possible unless corrective measures are applied. Regarding the pre-existing structure, the capacity to support new weights that it has must be considered. This parameter is not as decisive as the urban one since the pre-existing structure can always be rehabilitated and reinforced.

Do I need a rigger to carry out an extension?

In most cases yes. The best thing is to consult the municipal technicians of the municipality where the work will be carried out.

What is the Work Direction or the Facultative Direction?

The architect and rigger, developing the functions of Construction Director, Execution Director and Safety and Health Coordinator make up the Facultative Management of a work.

How long will it take to give me the building permit?

A license for an extension or new work is a major works license in most cases. Usually the minimum we have seen throughout our professional career is 6 months. However, some municipalities, the ones that take the longest, can take up to 2 years.

What documents should a basic project contain?

It consists of graphic and written documentation:

  1. Urban justification.
  2. Descriptive memory (the regulatory parameters that the intervention will achieve are established. For example: the facades will insulate the regulatory minimum which is U=0.3 W/m2K).
  3. Floor plans with the distribution, elevations, sections and facades, the regulatory justification (urban planning, habitability, cte).
  4. Budget per chapters. It is an approximate budget only assessing the structure, the chapter of work, the chapter of installations, without going into the details of each of the games that are within the chapters.

What documents should an implementation project contain to carry out an extension?

In the same way as the basic project, the execution project is composed of graphic and written documentation:

  1. Construction memory (all the systems – envelope, structure, installations – and the benefits that have been achieved with the concrete construction solution are described constructively. For example: the facades will be composed of a double ventilated sheet of brickwork. The sheet perforated brick interior and double hollow brick exterior with 20 cm thick PU projected polyurethane interior insulation and will insulate U=0.15 W/m2K).
  2. Justification of the Technical Building Code.
  3. Construction and structure detail plans, carpentry drawings, material plans.
  4. Instructions for use and maintenance.
  5. Quality control plan. For example, in the specific case of insulation: both documentary and on-site insulation checks will be prescribed, which will consist of: verifying the manufacturer’s technical data sheet – checking material conductivities, densities, etc. – check the CE marking, and most importantly carry out random thickness control tests, in this way it can be prescribed, that by means of a needle the insulation facing is pricked every 10 m2 to check that the thickness is not less than 20 cm depth).
  6. Measurements by parts and unit of work. (each item of work will be described qualitatively and assessed quantitatively; for example.
  7. Structure calculation memory.
  8. Energy certificate.
  9. Geotechnical study
  10. Topographic study.

Why is a new house better than an old house?

Making an analogy with cars, you cannot compare the performance and safety quality of a current car and one from the 20s. This is due, apart from commercial progress, to the progress of safety regulations and other regulations. The same thing happens with houses: the first thermal regulation that requires insulation is from 1979 ¡a measly 3 cm on facades!, the first CTE was from 2006 and already required about 6 cm of insulation and the current CTE demands at least about 8 cm. The insulation, the condensations, the hermeticity, the water tightness, the deformations of the structure, the earthquake resistance of the structure, etc. All building parameters are regulated by regulations that are improving year after year.

For these reasons, it seems clear that the more recent a construction, the better it will be with respect to these objective and quantifiable parameters mentioned above. However: an old house, with proper rehabilitation, could achieve the benefits of a new one.