It is a recreation of the proposal for à redent housing, formulated by Le Corbusier in 1922 for an urban fabric with a density of 300 inhabitants per hectare and luxurious housing. The GATCPAC project, aimed at social housing, also places the complex in a north-south direction, so that housing is always oriented to the south and east. Each home is accessed via a long, covered corridor that is always on the north and west side. The blocks, long and narrow, are solved with a metal structure of two passages. The ground floor has a covered terrace in front of the living room. Upstairs, each pair of bays has three bedrooms, so the central bedroom is compensated. The resulting density is 1,140 inhabitants per hectare, much lower than that of traditional urban fabrics on closed house squares.

Casa Bloc is an apartment complex for labourers promoted by the Generalitat de Catalunya in 1931, just when the Second Republic had been established. The complex is made up of five blocks of flats joined at the corners and they define a new urban layout, similar to Le Corbusier's Domino houses. All the blocks are raised on piloti to achieve a continuous green surface that is accessible by foot, without having to cross a single street. Originally, the complex was equipped on the ground floor with all the ancillary services that community life requires: cooperative, library, nursery, social club, free space for sports, etc., only the school had been ruled out because there was already one at the side of the street. Unfortunately, these community services were never built due to the outcome of the Civil War. The typology chosen for the dwellings is the duplex one because it reduces circulation spaces and facilitates ventilation through both façades; the GATCPAC architects had already tested this typology in another group of dwellings promoted by the Generalitat de Catalunya on the same street, albeit on a much smaller scale. Access is through four vertical cores, located at the corners, which lead to the corridors that provide the entrance to the dwellings. All the rooms have natural light and transversal ventilation, since the arrangement with isolated blocks allows the section of the building to be adapted to the needs of the dwellings and thus avoid the small interior patios that are obligatory in Barcelona's Eixample.

It was built during the Second Spanish Republic by order of the Generalitat, which was then chaired by Francesc Macià. The initial idea was to dignify housing for workers, following what Central European rationalism of the early twentieth century proposed, and with the clear influence of Le Corbusier's Immeuble-Villa (1922). Architects were fleeing from the proposals that the city had previously built during the dictatorship of Primo de Rivera, also known as “Cheap Houses”, but at the same time they were moving away from the idea that Ildefons Cerdà had implanted in Barcelona’s Eixample. A new system that, from the housing unit, could cover the entire urban area.

The 170-metre-long site is located in the Sant Andreu district, on the outskirts of Barcelona at the time, and close to the factories that had been set up decades before. The implantation is made in double U and consists of 5 thin and elongated blocks that articulate with each other through the vertical communication cores, forming a unit. In height it corresponds to three strips of a duplex of 70 square metres, giving a total body of six floors with a corridor-terrace every two.

The access to the houses is made by the access galleries that leave the respective nuclei and cross horizontally all the set, proposing elevated streets that had to foment the relation between the neighbors. The duplexes are distributed on the ground floor with toilet, kitchen, living-dining room and terrace, while on the upper floor the rooms of variable number according to the needs of the user are located. Communication between plants is done through an interior staircase.

The north-south orientation of the site allows the access galleries to be placed in the most unfavorable disposition with respect to the sun, taking advantage of the location of the kitchens and the bathroom on the ground floor that act as a filter with respect to the most private areas. In any case, the ventilation and lighting of these spaces is done through high windows that avoid direct visual contact with the neighbours. Therefore, the rooms enjoy the best possible sun and, having a façade on both sides, the optimal cross ventilation for living is achieved.

The architects of GATPAC followed the postulates of the IV Congress of CIRPAC, building on laminated steel structures separated from the enclosure, which allows to lighten the weight of the building because the walls are thinner. Consequently, there are savings in the foundation because it is lower. This makes it easier for the blocks to be raised on stilts, encouraging free movement between the resulting urban spaces, interrelating them.

The flat roof was made with the vocation of having a program, in the same way that common spaces had been planned, such as bathrooms, consumer cooperatives, popular libraries, nurseries, workers' clubs, etc. The outbreak of the Civil War paralysed its construction process, which was resumed when the conflict ended, changing what had been planned. The houses were not intended for workers, but for the military, war widows and orphans, police and teachers. The set was distorted by building the so-called ghost block, which broke the original scheme by changing the double U for a 6.

In mid-2008, the ghost block was destroyed, happening to have a total of 169 houses and 14 premises. Barcelona City Council later opened one of the residential modules as a museum to the public, preserving all its original elements.

The building is fully integrated into the rationalist approaches of the GATCPAC (Group of Catalan Artists and Technicians for the Progress of Contemporary Architecture), constituted in 1930 as one of the three groups -the Eastern group- of the Spanish GATEPAC. The Bloc House, proposed as an open and secluded structure (following the "redent" typology of Le Corbusier's Ville Radieuse), must be understood as a residential prototype for the new Barcelona provided for in the Macià Plan, carried out by GATCPAC in collaboration with Le Corbusier. The ground floor of the building was used for collective services such as nurseries, meeting rooms, library, etc., in close connection with the free spaces for community gardens. Housing was considered within the parameters of the "minimum housing", debated in Europe since the 1920s.

The Bloc House of Sant Andreu, designed by the architects Sert, Torres Claver and Subirana, was built in the 1932-36 period by order of the Working House Commission of the Generalitat de Catalunya, as a housing building for workers. At the time it was built, the technological level of the Casa Bloc was very correct, in relation to the modesty of its budgets and very consistent with the general approach of the project. With the Republican defeat in the Spanish Civil War, a process of cultural and physical decline of the Republican heritage begins, which also affects the Bloc House. Over the years, the initial degradation of the building worsened to different levels. The recovery of the set has recently begun (in a first phase and only of a part), trying to give back to it the aspect and the minimum conditions that had to have this work, one of the first and most genuine samples of rationalism in Catalonia, which was cut short by the Civil War and its consequences.