Keywords

1 Introduction

The regeneration of mid-20th century residential estates is a major concern of the public Administrations (eu2010 2010; Ministerio de Fomento 2013; Jefatura de Estado 2013). The attention that city centers used to receive is now focused on peripheral residential areas. A number of problems of different nature can be identified in those neighborhoods (García Vázquez 2010). Firstly, from an urban point of view, they are commonly characterized by a certain level of isolation, a lack of facilities and the deterioration of their public space . Secondly, from a social perspective, many of them have also been identified as vulnerable neighborhoods, with high unemployment rates and low educational levels (Hernández Aja et al. 2015). Finally, architectural deficiencies come to light due to the inadequacy of their technical equipment, the low energy efficiency of these constructions and a lack of building maintenance. This situation has stimulated the interest of researchers to seek of solutions that can make cities more enjoyable and sustainable .

In concordance to what some authors, such as García Vázquez (2015), point out, one of the main causes behind the obsolescence of these buildings is the maladjustment that exists between the housing typologies and the needs and expectations of contemporary society.Footnote 1 These social housing projects were planned during Franco’s regime to satisfy the basic needs of the Spanish working class of the 1950s. However, the advent of democracy a couple of decades later would see the rise of a new kind of house-demanding citizens, the profiles of which were very different. Accordingly, new social dynamics challenged previous architectural programs.

A deep knowledge of these housing typologies is a mandatory first step towards evaluation of their obsolescence . However, the study of the housing typologies built massively in Spain has not received enough attention and represents an unusual topic in contemporary architectural research. The main objective of this paper is to address that situation and provide potentially relevant information in order to: (1) identify housing unit typologies (2) analyze their characteristics. Specifically, this study is focused in the analysis of the H-plan block housing unit typology, given its wide-spread use in these public states.Footnote 2

The H-plan block has been defined as a multi-story apartment building organized with 4 housing units per floor and a communication core. These buildings can be connected to others creating linear structures. The housing units have two facades: one towards the public space and another facing a small, inner courtyard .

2 Methodology

This research analyses the housing typologies of 44 H-plan blocks built in Spain between 1957 and 1981. The sample is mainly composed of buildings from western Andalusia, where a total of ten different archives were consulted.Footnote 3 For the identification of other cases in Spain, the complete collection of the journal “Hogar y Arquitectura” (edited between 1955 and 1977 by the national organism Obra Sindical del Hogar) was thoroughly reviewed. After the total sample collection by one or other means, the layout of each typology was redrawn in order to measure and analyze them. Three-bedroom units were identified in thirty six of the samples and four-bedroom units in the remaining eight. To carry out this typological analysis, only the blocks with three-bedroom units are taken into consideration consideration given that it is the only group with enough representative cases that would allow a size comparison analysis. The statistical analysis in Sect. 4.1 “Chronology of the H-plan block” includes them all.

The hypothesis to be tested is that quoted by Ignacio Paricio in regards to massive housing projects in Spain (Paricio Ansuátegui 1973a): “the width and depth of the plot have a significant influence in the housing layouts”. Consequently, this study analyses the different typologies of the houses based on the relationship between the width and the depth of the blocks. The work “Estudios de tipología de la vivienda: Entre Medianeras” (Paricio Ansuátegui 1973b) regarding H-plan blocks from Barcelona was used as a reference. As part of this study’s Conclusions a general characterization of the H-plan social housing block type is described, in the hope that it will serve as a reference for future regenerative initiatives.

3 Results: Typological Analysis

In this section, the typological analysis of 36 H-plan housing blocks types built between 1957 and 1981 has been carried out. An initial classification of the housing units into different groups is presented regarding how the day area (living room and kitchen) and the night area (bedrooms) are connected. These groups are named Type 1, Type 2 and Type 3. For each housing Type (1–3), a characteristic layout is defined based on the most abundant distribution. With that layout as a reference, the units within each Type are again analyzed and their differences regarding the “characteristic layout” are described. The dimensional relationship between the depth and the width of the blocks is taken into consideration for this last examination.

3.1 Type 1—Housing Units

Type 1—housing units (the main dimensional characteristics of which are summarized in Table 1) are defined by the dependence between the day and night areas, i.e., the access to the night area from the main entrance interrupts the circulation between the kitchen and the living room. 29 cases out of the 44 analyzed correspond to this type. Among them, 89.7% adhere to the characteristic layout of this Type, 6.9% are a variant that follow an irregular perimeter and 3.4% show a different solution. The first two groups will be described in this study.

Table 1 Type-1 housing units. Basic characteristics
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3.1.1 Housing Units with a Characteristic Layout

The characteristic layout of Type-1 housing units fits the following scheme: a main entrance with a small hall, the kitchen located nearby and adjacent to the bathroom (comprising the wet area of the house), the living room across from of the kitchen and the night area organized around a small corridor. Terraces are associated to the living room or the kitchen (Fig. 1a).

Fig. 1
figure 1

Type-1 housing units. a J. Rebollo Dicenta (1974) La Fuensanta, Córdoba; b R. de la Hoz, G. Olivares (1965) Parque Cruzconde, Córdoba; c L. Recasens (1967) Pino Montano, Sevilla; d J. Álvarez et al. (1971) Moratalaz, Madrid; e J.E. Alba et al. (1976) Vega de Arriba, Asturias; M. Riquelme (1973) La Granja, Jerez; g P. Genovés (1975) Alcosa, Sevilla; h S. de la Fuente (1969) La Granja, Jerez

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Extension towards the central courtyard

A common strategy in the H-plan Type-1 group is the extension of the housing unit towards the inner courtyard , widening the space for any one of the rooms. This is achieved through more irregular shapes in the inner façade, in contrast with the basic rectangular shapes. That shape reconfiguration primarily affects the kitchen and the outdoor laundry area (terrace), which are placed closer to the communication core of the building. Of all the cases analyzed within this group, 55% of them make use of this scheme in their layout. This solution provides greater flexibility when it comes to locating the kitchen and living room. Locating the terrace on the exterior can also offer the advantage of serving as a ventilation space for the bathroom (Fig. 1b).

An inverse relationship between the depth of the unit and the use of this strategy was confirmed: 90% of the units with depths between 6 and 7 m partially or completely locate the kitchen in the inner courtyard of the building while this trend becomes less prevalent in units with larger depths. Among units with a depth of 7–8 m, for instance, only 55% adopt this solution and that percentage goes down to 20% in the group of units that are at least 8 m in deep.

The location of the kitchen in the inner courtyard is almost a must in units that are under 7 m deep. Figure 1c shows the case of a unit that is under 7 m deep that maintains the kitchen within the parallelepiped, forcing the longitudinal extension of the living room towards the façade, thus generating a very problematic geometry.

Flexible Circulation

Flexible circulation is another characteristic of Type-1 housing units. This solution is found in a minority of cases (31%), and is only observed in blocks built after 1970. The most common strategy is to connect the entrance hall with the night-area corridor through the kitchen. This generates a circular itinerary around the wall that divides living room and kitchen.

Once again the layout of the unit depends on its depth. Among the units with a flexible circulation, two different configurations exist: those with short depth (around 6 m) have a small hall independent from the living room but with direct access to an L-shaped kitchen (Fig. 1d); while those with larger depths (around 8 m) maintain a rectangular-shaped kitchen. In the latter case, is possible to find two different ways of orienting the kitchen towards the inner façade: either parallel or perpendicular to it. The 90° rotation of the kitchen is an effective solution that allows flexible circulation while moving circulation away from the cooking area (Fig. 1f).

There is only one case in which a circular itinerary is not achieved around the kitchen but through the living room (Fig. 1g). This layout has two consequences: the mandatory shift of a second bedroom towards the inner façade and the need of a large corridor that goes through the entire unit. To be implemented, this layout requires large surface areas.

3.1.2 Housing Units with Irregular Perimeters

Figure 1h shows the case of Type-1 units whose layout differs from the characteristic distribution. Its main virtue is the rejection of the rectangular-shaped unit and a commitment to a more irregular contour. This novelty is not only a matter of a formal composition of the perimeter of the façade, but a reflection of the search for a more flexible architectural approach. This strategy could be understood as a new way of approaching the design of the H-plan block : rooms do not need to fit the rectangular shape of the house any longer, but instead, it is their aggregation what defines the shape of the block.

In these non-characteristic units, the main bedroom is placed at the end of the corridor and has a double façade, one towards the public space and another towards the inner courtyard . The other two bedrooms are next to the living room. This exceptional layout of the night area allows all the bedrooms to ventilate directly to public space (which is unique among all the Type-1 samples), it also provides independence and geometric proportion to the rooms and facilitates flexible circulations.

3.2 Type-2 Housing Units

Type-2 housing units (the main dimensional characteristics of which are summarized in Table 2) are defined in our study as those in which access to the night area can be done independently of the living room-kitchen circulation. No characteristic layout was found due to the few cases identified within this Type given the differences between them.

Table 2 Type-2 housing units. Basic characteristics
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Figure 2a shows the floor plan of the smallest housing unit (60.22 m2) found within this Type. We observe that the kitchen and living room comprise an architectural unit that is independent from the night area, making it possible to reach the main entrance directly from the bedrooms. This solution is achieved by placing the wet area across from the entrance hall and by opening the kitchen towards the living room. A central corridor organizes the circulation within the unit.

Fig. 2
figure 2

Type-2 housing units. a R. Espiau (1958) Tiro de Línea, Sevilla; b A. Delgado Roig (1964) Tiro de Línea, Sevilla; c A. Delgado Roig (1957) Bami, Sevilla; d G. Olivares James (1970) Santuario, Córdoba

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Two cases (Fig. 2b, c) are found in which areas are functionally separated by means of bays. One of them is designated to the bedrooms and the other to the living room, kitchen and bathroom. The main difference between these two blocks is the orientation of the load-bearing structure.

The unit displayed in Fig. 2b displays load-bearing walls following the same direction of the communication core. This solution is hard to implement in units that are less than 9 m deep and it also requires the existence of a window on the façade to ventilate the main bedroom. This last feature prevents the connection of additional buildings that would, in turn, create linear blocks. In this unit the wet area is located immediately beyond the communication core, a place generally reserved for the main entrance in this typology. Consequently, the access to the unit is moved to a middle point between the bedrooms and the kitchen, after crossing an outdoor open corridor. This layout allows a 4 m reduction in the average unit depth.

The unit shown in Fig. 2c, on the contrary, displays an orientation that is parallel to the main facades. Bedrooms are positioned facing the public space , while the living room, kitchen and bathroom ventilate facing a large, inner courtyard . This layout of the bedrooms forces these blocks to increase their depth.

The best-suited housing units among Type-2s are those exemplified in Fig. 2. Regardless of the increase in the unit’s depth, an efficient organization of day and night areas is established, with the entrance hall serving as the connection space between them. The night area is planned around an autonomous hall that communicates the bedrooms and the bathroom. The kitchen and living room open directly onto the main entrance hall. This layout avoids the need to reach the bedrooms crossing through the living room but forces the orientation of two of the bedrooms towards a small inner courtyard .

3.3 Type-3 Housing Units

Type-3 housing units (the main dimensional characteristics of which are summarized in Table 3) are defined in our study as those in which the night area is disaggregated, i.e., access to some of the bedrooms, but not to others, must be done through the day area. Once again, no characteristic distribution was found for this Type given the low number of unit types (only two) that follow this layout.

Table 3 Type-3 housing units. Basic characteristics
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The first (Fig. 3a) has a depth of 6.9 m and a surface area of 64.78 m2. The disaggregation of the bedrooms is due to the central position that the living room takes in the unit. The wet area is planned with the bathroom facing the living room, placed so that it ventilates through the courtyard . The kitchen is located next to the main entrance.

Fig. 3
figure 3

Type-3 housing units. a J.L. Delgado Lejal (1967) Los Corrales, Cádiz; b M. AmbrósEscanellas (1966) Manoteras, Madrid

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The second example of this Type (Fig. 3b) is 7.44 m in depth and has a surface area of 88.49 m2. Its larger dimensions allow a different organization of the disaggregated night area. A rare solution is applied for one of the bedrooms: it is located facing the central courtyard of the building. As a consequence, additional space is available for the functional division between the living and dining rooms. Two exceptional spaces can be seen in this unit type: a built-in closet in a common area and a second bathroom. The kitchen is open to flexible circulation, connecting the main entrance hall with the night area.

4 Discussion and Conclusions

4.1 H-Plan Block Chronology

The research carried out shows a gradual increase in the construction of H-plan blocks from 1950 to 1980: out of the 44 cases analyzed, only two (4.55%) were built in the 1950s, 18 (40.90%) in the 1960s, 22 (50%) in the 1970s and two (4.45%) during 1981. The explanation for this has traditionally been based exclusively on economic reasonings. Ignacio Paricio argues in his article “Las razones de la forma en la vivienda masiva” (Paricio Ansuátegui 1973a) that the reduction in building costs drove the typological evolution of the residential states . Paricio identifies two of the economic-based decisions that influenced this typological evolution of the blocks the most: a reduction in the length of facades and increase in the number of housing units per entryways. Indeed, the H-plan block typology produces significant savings in construction expenses in comparison to linear blocks, the most extensively used until then. The lower costs of H-plan blocks are based on these new traits: the implementation of four instead of two housing units per floor and the reduction of the thickness of the inner-courtyard façade to an average of 15 cm or even 10 cm. Paricio pointed out in his study that the construction of residential states in Spain in the seventies was monopolized by H-plan block typology. The chronological distribution shown in this study clearly reinforces that theory.

4.2 Generic Housing Unit of the H-Plan Block

It is possible to characterize the generic housing unit found in H-plan blocks built in Spain between 1957 and 1981. As demonstrated by the typological analysis, the most extensively used layout among the three-bedroom housing unit samples is that defined as Type 1 (80.55%). Type-2 and Type-3 account for a minority of layouts. Only five cases are identified within the Type-2 group and two as Type-3s.

The generic housing unit is comprised of a main bedroom (11 m2), two secondary bedrooms (8 m2), a living room (17 m2), a kitchen (7 m2) and a bathroom (3 m2). Transition spaces are reduced to distribution areas. A second bathroom is only present in 11% of the cases.

This study has revealed that the average built surface area is 76.62 m2, though an increase in the size of the units can be seen in the subsequent decades. In the 1950s, the average surface was 68.83 m2, in the 1970s it rose to 79.38 m2. Accordingly, the average usable surface area changed from 56.52 to 64.69 m2 during those two decades. Their structure is basically made of reinforced concrete. Double bays are generally used, oriented along the main facades. Exceptionally, the load bearing structures can be found following in the same direction as the party walls. It can be stated that the units are wider than they are deep. An analysis of the width-depth ratios shows that the main facades are 1, 3 times larger than the side facades. Their average depth is 7.17 m2. The average dimension of the inner courtyard is 5.44 m. The bathroom and kitchen are commonly built close to each other, so that 86% of the housing units have a comprehensive wet area. However, the use of a single wet area decreases slightly with time: from 93 to 78% between 1960s and 1970s.

4.3 The Architecture of the Housing Unit

This research has revealed the high level of homogeneity that characterizes the H-plan block social housing estate typology. It is remarkable that 72% of the housing units analyzed follow the exact same layout (described in this study as “Type-1 characteristic layout”). This high level of homogeneity becomes determinant when defining the obsolescence of H-plan block housing typologies in as much as it suggests that the study of a few cases can be representative of a larger sample and, therefore, solutions may be extrapolated. Even though some creative projects can be identified, the vast majority of the blocks contain a standardized-type house that fits within a parallelepiped. Housing unit design is reduced, consequently, to a matter of establishing its width and its depth and adapting a standardized layout to those parameters.

In fact, a relationship between those dimensions and the different layouts has been proven in this study: the geometry of the rooms, the location of the kitchen and terraces and the possibility of flexible circulations depend on the width and depth of the housing units.

The work presented here brings to light some important aspects of social housing architecture and aims to contribute to their regeneration by expanding the existing knowledge.