There are important differences between Spanish brickwork and its British counterpart. Mostly due to the usage provided in each country.
In the UK most buildings are constructed using load bearing walls, while here in Spain brick walls are used as infill panels and rarely as load bearing. Most existing load bearing brick walls buildings in Spain are from last century. Why is this? The answer is “earth quakes”.
If we take a look at a seismic map of Spain we will be able to see that Spain is a country marked as high risk area and interesting enough the areas which are highly rated are precisely located around the coast of Granada, Malaga, Almería, Murcia and Alicante. The map also provides the so called basic seismic acceleration (a characteristic value of the horizontal acceleration of ground surface) a coefficient that takes into account the influence of different types of earthquakes envisage on each of these areas during a long period of time.
The strongest officially recorded earthquake ever in the UK was on 7th of June of 1931 in Dogger Bank, (North Sea) with a 6.1 of the Richter scale.
In the twentieth century, the use of brickwork in Spain declined due to earthquakes. The San Francisco earthquake of 1906 among others revealed the weaknesses of brick buildings during an earthquake. Most buildings in San Francisco collapsed during the earthquake, due to the cement-based mortar used to hold the bricks together. During seismic events, the mortar is not very elastic and highly fragile, cracking and crumbling occurs when a vertical wall is faced to a violent shake and bricks are no longer held together.
General characteristics of good bricks.
The brick should ensure a good thermal and sound insulation of houses. On facades, bricks with holes should be laid to retain the air within the holes or should be filled with an insulating material to ensure protection against external temperature. Furthermore, when used in interior walls partitions, its good acoustic insulation values are appreciated to reduce noise from the neighboring houses. If these two characteristics, are met we can obtain good value for money and obtain a good contribution to both heating and air conditioning energy saving.
But in addition, the bricks must withstand storms, frost and any inclemency from weather conditions. Otherwise, runs the risk of damage and breakage due to pressure that originates in each piece when water is filtered. If this solidifies and increases volume, can cause cracks in the brick wall. A way to avoid this problem is to take render the brick walls. However the risk of freezing weather is highly exceptional in this part of Spain.
Another consequence of moisture is the expansion, which increases the dimensions of bricks due to the uptake of atmospheric humidity. The expansion by humidity can also cause the appearance of cracks and fissures in vertical and horizontal elements. This situation, can take place in both load bearing walls and none load bearing walls.
In this sense, water-repellent bricks considerably reduce the suction of the pieces and produce a repellent effect of rainwater. When they come out of the oven, these bricks are dipped in an aqueous solution of derivatives of silicone that goes into each piece. This treatment induces raindrops from slipping into the brick surface, thereby improving the conservation status of the bricks and makes them less vulnerable to the passage of time.
The most frequent use of facing bricks is in external façades. Façades with this type of material are widely used since it is very resistant to water, with a great capacity for absorption and compression. This brick can be found as perforated bricks or solid.
In addition, there are manually made facing bricks, manufactured by hand and is used for its aesthetic appearance; low suction; water-repellent, with increased impermeability to water in the liquid state; and clinker bricks, manufactured with special clay that achieve absorption of water below the 6% and are more resistant than the normal ceramic brick.
When we intend to raise a partition or external wall, there are two essential types of brick: hollow bricks and perforated bricks. They are the most commonly bricks used in Spain. They provide a good guarantee for the implementation of durability and resistance, both, to impacts and for suspended loads. Bricks, in addition, have a good behavior against fire therefore its use in the construction of fireplaces and barbecues by using refractory bricks.
Main categories of bricks in Spain.
They are those that have horizontal perforations on the stretcher side (lateral side). They are used both in internal partitions normally they are plastered on both sides. There are hollow brick, with traditional format, and with various metric measurement up to 30cms, and hollow brick of large format, with a length exceeding 30 centimeters, a thickness equal to or exceeding 4 centimeters and a dimension less than 14 centimeters for its header or head face. In addition, according to their thickness, we can have bricks with singles, doubles or triples hollows.
They have vertical perforations on the bed side with a of volume greater than 10%. They are used in interior and exterior masonry walls. The most common measures are the metric and the Catalan type, with a length ranging from 24 to 28 centimeters, respectively.
In addition to the traditional forms of bricks, there are pieces with different profiles to adapt to any job. The ceramic material is easy to mould and is therefore easy to obtain bricks of various forms. There are molds special made for those parts that form an arch, finish off a wall or are to be laid in special corners. Its use is advisable, when its design facilitates and improves complicated and singular designs.