A BUILDING TECHNIQUE FOR THE REALIZATION OF OPENING BEARING WALLS OF SALENTO

In Salento the stones most frequently used for construction are called tuff , soft limestone of marine sedimentary origin, easy to work with hand tools, mannare (two bladed axe), and easily squared off in regular ashlars. The specific weight is 1.300-1.400 kg/m3, the maximum load varies from 16 to 23 MPa. For cladding and masonry carparo is also employed, yellow gold porous very durable tuff rock, weighing about 1.750 kg/m3 with a breaking load between 80 and 185 MPa .
The need to create connections between adjoining spaces trough load bearing walls built in short time and at low cost has fostered the development, over the centuries, of a refined constructive system still in use today, albeit rarely and with some innovation, to produce openings with the use of local materials. This system is now prohibited by law, which prescribes, for the openings in the walls of rooms, in addition to local strengthening, a lintel in c . a. or steel, able to withstand the tensile stresses .
The construction technique involves the use of common equipment and local materials.
The first step is to draw on the wall the opening to be cut, with flat or curved transoms, usually with a width between 1.50 m and 2.70 m. Having drawn the desired opening on the wall, a strip of plaster is removed to control the structure of the masonry, then the key points are draw, Z-shaped holes approximately 50 cm, if there is only one floor above, or 70-75 cm if there are two storeys, or if the transom of the opening is flat.
The keys are drawn starting from the center line of the future opening . If the opening has a flat transom 5 key points are defined at a distance of about 25 cm, distance that increases to 50 cm for arched openings , with a reduction in the number of keys to 3 for widths up to 1.50 m. Then the holes are made with a chain saw , which replaced the handsaw and filled with concrete.
Originally a perfectly chiseled carparo ashlar was used without any mortar. After 6-7 days the wall is cut with the chain saw along the horizontal line drawn above the transom. After 1 day we proceed with the two vertical cuts along the jambs and after 1-2 days, after confirmation of the absence of failures, the masonry is cut, horizontally and vertically again with the chainsaw.
To complete, patches of plaster, trimming, in the case of delaminated the segments of transom and jambs of the opening.