After the Decree of 11 March 1941, which limited the use of steel, until the approval of the MV-101/1962 standard on “Actions in Building”, which repealed the previous limitations, the use of iron in building was restricted, giving rise to the corresponding regulation detailing the prescriptions in this respect during the design and execution of the work. (BOE nº 214, 2-8-1941). These regulations were based on prescribing technical solutions that would help to save iron, explicitly prohibiting its use in construction elements that could be built with other materials. In the rest of the constructive elements, the project design was urged to make the greatest savings in iron.
This affected the structural typologies, leaving aside the evolution made in previous years in the use of metal structures, frequently employed until 1936 (Lahuerta, 1965), as well as the construction of high-rise buildings. Therefore, with regard to vertical structural systems, during the entire period of the restriction, practically coinciding with the predominance of RENFE as a developer of housing for its employees, the ceramic brick load-bearing wall, without any quality control of the manufacturing process, was the structural system almost exclusively used as part of the misnamed “traditional construction” (Azpilicueta & Araujo, 2012).
Once the autarkic period was over and the restriction was lifted, we can see that it gradually gave way to reinforced concrete or mixed (reinforced concrete supports and metal beams) frame structures, being the predominant structural system in the construction period, where the railway workers’ cooperatives were the dominant promoter group in the construction of the dwellings under study (figure 1).
Figure 1. Structural systems and materials used in railway housing construction (1945-1989). Own elaboration
Although ceramic brick (solid, perforated and hollowed) was the main material used in load-bearing walls because it was considered a suitable material in any situation, the use of adobe and rammed earth was also permitted in those areas where its use was traditional and, with respect to masonry, its use was conditioned. An example of the use of masonry in the dwellings under study can be found in the 97 RENFE dwellings in Las Matas-Pinar-Monte Rozas (1963) or in the 54 RENFE dwellings in Vilagarcía de Arousa (1962).
The layout of the structural elements was conditioned by the imposition of the double-bay block that the 1955 Order on technical regulations and building standards for low-income housing prescribed, since, for a block width of between 8 and 9 m, it determined an ideal type of cell for social housing both in terms of surface area and for reasons of hygiene and economy, due to the fact that all the rooms had direct ventilation with the consequent saving in the construction of interior courtyards.
This solution was materialised by means of brick load-bearing walls on the façades and an interior parallel structural line, normally also made up of masonry walls, which also served to support the ridge and anchor the roof braces. In some cases, this intermediate structural line was replaced by brick studs or, exceptionally, it was built with reinforced concrete supports, as both the restriction imposed on the use of steel and the problems in the supply of materials made this option inadvisable. The bracing walls were placed in the party walls, especially in the case of grouped dwellings, or in the enclosure of the stairwells. The following figure (figure 2) is a frequently repeated example in the dwellings under study.
Figure 2. Two-bay cell in the building in block Q, Madrid-Tetuán. AMF. Project M-972-RL
For the row housing complexes, the solution was also designed with load-bearing walls perpendicular to the façade, and in this case, the façade walls acted as bracing.
However, although significant heights were achieved (up to eight storeys in the Valencia-Alameda development (figure 3), there was no quality control of the bricks used, which conditioned the irregular appearance of the brickwork in terms of colour, texture and even size before they were clad.
Figure 3. Development of 78 RENFE dwellings in Valencia-Alameda. AHF FV-0042
Regarding the thicknesses, in most of the cases of high-rise blocks studied, the traditional decrease in height is used to lighten the masonry, despite the fact that insulation issues were not considered. Thus, we find walls 43 cm thick on the ground floors, without cladding, which are reduced to 28 cm, without cladding on the upper floors. It is not possible to give details of the construction methods used because another common feature of the way in which the projects were drawn up is that the level of construction detail was very basic and brief and because most of the masonry was clad. The most common grouting detailed in the projects consulted was cement mortar of 200-250 kg per m3. The masonry was prescribed to be “well locked” with the execution of keys at the joints, and a horizontal joint width of no more than 12 mm.
The proposals for 48 dwellings in San Cayetano, in Cordoba, or the 97 dwellings in Las Matas, in Madrid (figure 4), which combine masonry walls for the ground floors with a perpendicular arrangement and the rest in clad brickwork, and in none of the cases studied is a reticular structure of reinforced concrete or steel profiles used, for the reasons mentioned above, despite the widespread use of these solutions in Europe or the United States and the Spanish experiences of the previous period (Azpilicueta, 2004), are unique. was also prescribed. (Martínez-Corral & Cuéllar, 2020).
Figure 4. Construction section of the RENFE housing group in Las Matas (Madrid). AMF, project M-5476-VP
For the foundations, given the structural system described, the most repeated solution was that of continuous trenches, normally of mass concrete and to a lesser extent of masonry, and, in the cases of intermediate bays based on pillars, they were combined with isolated foundations on the corresponding structural line which were not tied. Only in a few cases is a deep foundation based on shafts used, and we have only detected one case where the project determines a foundation based on piles, although no details of these are given. On top of the foundations, normally made with mass concrete of 200 kg of cement per m3, and up to the level of the ground, carbonite concrete was filled in at a thickness of between 20-30 cm and the walls were erected on top of this.
Azpilicueta, E. (2004). La construcción de la arquitectura de postguerra en España (1939-1962) [Phd, E.T.S. Arquitectura (UPM)]. http://oa.upm.es/23197/
Azpilicueta, E., & Araujo, R. (2012). El mito industrial. Revista Tectónica, 38, 4-19.
De León, J. L. (1947). Nociones sobre el hormigón pretensado. Revista Nacional de Arquitectura, 66, 231-233.
Lahuerta, J. (1965). Situación actual de la edificación en España. Arquitectura, 79, 43-50.
Martínez-Corral, A., & Cuéllar, D. (2020). Las soluciones constructivas en la vivienda durante el franquismo: El caso de la vivienda ferroviaria. Informes de la Construcción, Vol. 72, 558, e341, abril-junio 2020. https://doi.org/10.3989/ic.71047