Report: 2

Building Type: Traditional adobe house

Country: Argentina

Author(s): Virginia I Rodriguez, Maria I Yacante, Sergio Reiloba

Regions Where Found: Buildings of this construction type can be found in in the province of San Juan. This type of housing construction is commonly found in rural areas. The building code allows this type of construction only in rural areas. However, as the city has grown, the current urban area now includes adobe block constructions that were built in the past (when the area was rural).

Summary: This construction type is a single-family house. In general, it is a single-story building, an isolated construction found in the rural areas of San Juan and Mendoza. The traditional adobe block masonry walls are reinforced with foundations and plinth structure, which provide structural strength. A deficiency in this type of construction is that the adobe blocks deteriorate due to prolonged exposure to humidity.

Length of time practiced: 76-100 years

Still Practiced: Yes

Building Occupancy: Single dwelling

Typical number of stories: 1

Terrain-Flat: Typically

Terrain-Sloped: 3

Comments: This is a traditional construction practice that has been practiced in San Juan for many years, but since 1948 it has been pract.

Plan Shape: Rectangular, solid

Additional comments on plan shape: The typical shape of a building plan for this housing type is rectangular.

Typical plan length (meters): 12

Typical plan width (meters): 8.4

Typical story height (meters): 3

Type of Structural System: Masonry: Earthen/Mud/Adobe/Rammed Earth Walls: Mud walls with horizontal wood elements

Additional comments on structural system: The vertical load resisting system is adobe block walls. The earthquake-resistant system consists of adobe block walls of 40 cm thickness, which generally meet the quality standards and architectural requirements (small openings, heights shorter than 3 m). In general, the roofs are light (weight less than 150 kg/sq m). On the upper part of the wall, there is a reinforced concrete bond beam, and on the bottom there are foundations and plinth structure.

Gravity load-bearing & lateral load-resisting systems: 40-cm-thick block walls joined using mud mortar.

Typical wall densities in direction 1: 10-15%

Typical wall densities in direction 2: 15-20%

Additional comments on typical wall densities: The total wall density is 0.215; it is 0.153 in the X-direction and 0.11 in the Y-direction.

Wall Openings: The typical house has approximately seven openings, with an average area of 1.60m2 . These openings are: 5 (five) windows, placed in the middle of the walls, and 2 (two) doors. The doors are placed to one side of the wall. The opening area is about 10.40% of the whole wall area.

Is it typical for buildings of this type to have common walls with adjacent buildings? No

Type of Foundation: Shallow Foundation: Reinforced concrete strip footing

Additional comments on foundation: Concrete, with a minimum cement of 180 kg/sq m and 30 % of stone. The top of the plinth is 30 cm above the ground level.

Type of Floor System: Other floor system

Type of Roof System: Roof system, other

Additional comments on roof system: The roofing system consists of mud and cane roof with exterior finishing of clay tiles supported by round logs. The roof is considered to be a flexible diaphragm with a maximum weight of 150 kg/sq m.

Additional comments section 2: When separated from adjacent buildings, the typical distance from a neighboring building is 5 meters.

Who is involved with the design process? Other

Roles of those involved in the design process: In the beginning, this type of construction was designed and built by engineers and general builders, but later the same construction began to be made by the owners.

Who typically builds this construction type? OwnerOther

Roles of those involved in the building process: When this construction was first used, the builder did not live in this construction type. However, later on it was built by the owners themselves; in general, owners of this type of construction are people without any chances of building their houses with other building materials (due to their high cost).

Expertise of those involved in building process: This construction began to be practiced after the 1944 earthquake, as an alternative to improve the seismic behavior of the traditional adobe block construction. The design of adobe construction was largely based on the local building experience related to this kind of construction. This experience and the new information gained after the earthquake helped in improving the adobe construction practice. This construction proved to be an economic solution as the local material and skills were used and the traditional construction practice was followed.

Construction process and phasing: The owner of the house usually carries out the construction. It begins with the manufacturing of adobe, the filling in of foundations and plinth construction. After that, the adobe block masonry is built, caring that the blocks are perfectly joined. Then, the frame of the top reinforcement concrete beam is made, and the iron bars are placed to fasten the round logs of the roof. The frame is filled in with concrete. The round logs are placed and fastened every 60 cm. After that a 5cm-wide coat of cane and mud is placed. This coat is later made waterproof with asphalt, finishing the process with the placement of Spanish tiles. The tools and equipment typically used are: wheelbarrows, grub hoe, and matrix for the manufacturing of adobe blocks; spatulas, shovels, hoes, baskets, saws, pliers, levels, cement mixers, etc., are used in the whole process. This type of construction is generally designed for its final constructed size, but the owner also builds additional parts, generally without any professional input.

Is this construction type address by codes/standards? Yes

Applicable codes or standards: 1951 Building Code of the Province of San Juan, Earthquake-proof Norms Concar 70, Argentinean Earthquake-proof Norms 80 and 1990 INPRES CIRSOC Norms.

Process for building code enforcement: The construction process is controlled by the corresponding state authorities.

Are building permits required? Yes

Is this typically informal construction? Yes

Is this construction typically authorized as per development control rules? No

Additional comments on building permits and development control rules: This construction is subject to regulations and the approval of plans.

Who typically maintains buildings of this type? Owner(s)

Additional comments on maintenance and building condition: Usually, it is the owner who maintains the building, but given the low economic levels of the owners there is generally little or no maintenance and over time the construction deteriorates.

Unit construction cost: Unit construction cost per m2 of built-up area is approximately US$ 137.

Labor requirements: The typical amount and skill-level of labour employed in the construction of a typical building of this type of housing is 380 man-days (assuming 8 working hours/day). Experience is required in the selection of the land. Knowledge is necessary about the adequate mix proportions to manufacture the adobe blocks, and about foundations, plinth structure, top reinforcement beam, and round log. The tools needed in this construction type are not many: shovels, baskets, hoes, pliers, spatulas, etc.

Patterns of occupancy: In general, there is a single family in a housing unit.

Number of inhabitants in a typical building of this construction type during the day: <5

Number of inhabitants in a typical building of this construction type during the evening/night: <5

Economic level of inhabitants: Very low-income class (very poor)

Additional comments on economic level of inhabitants: House Price/Annual Income (ratio): 5:1 or worse 1. Below are the general guidelines related to the economic status of the inhabitants: Very Poor= lowest 10% of the population (per GDP), Poor= lowest 30% of the population, Middle Class= from the lowest 30% up to the top 20% of the population, Rich= top 20% of the population. Values are variable: the adobe blocks may be manufactured by the owner of the house and the masonry may also be made by the owner; canes grow on the banks of the water channels in the area. All this results in a notable reduction of the overall construction cost. Economic Level: For Poor Class the Housing Price Unit is 12,000 and the Annual Income is 7,200.

Typical Source of Financing: Combination

Additional comments on financing: In the #50s, a part of the cost was paid by the government, in the form of a non-repayable contribution or grant, and the rest of the money was financed by a bank. Nowadays, the construction is completely owner financed; the owners are doing the construction by themselves.

Type of Ownership: Own with debt (mortgage or other)

Additional comments on ownership: The information in this chart reflects the period after the 1944 earthquake. After 1960, houses of this construction type were built directly by the owners, without any kind of external financing.

Is earthquake insurance for this construction type typically available? No

What does earthquake insurance typically cover/cost: Insurance policies for buildings make it explicit that disasters are not covered.

Are premium discounts or higher coverages available for seismically strengthened buildings or new buildings built to incorporate seismically resistant features? No

Past Earthquakes in the country which affected buildings of this type:

Damage patterns observed in past earthquakes for this construction type: In general, during the 1977 earthquake, the adobe block construction built in Caucete using the standards of 1948, suffered moderate damage (economically repairable); those built in the capital city of San Juan, under the same standards, were not damaged at all. Traditional adobe block houses, built without any kind of earthquake-resistant requirements, were seriously damaged during the same earthquake.

Additional comments on earthquake damage patterns: In the Capital city of San Juan, located at approximately 100 km distance from the epicenter, the intensity was between VII MMI and VIII MMI . It is important to mention that a wide area of about 1000 km2 experienced liquefaction.

The main reference publication used in developing the statements used in this table is FEMA 310 “Handbook for the Seismic Evaluation of Buildings-A Pre-standard”, Federal Emergency Management Agency, Washington, D.C., 1998.

The total width of door and window openings in a wall is: For brick masonry construction in cement mortar : less than ½ of the distance between the adjacent cross walls; For adobe masonry, stone masonry and brick masonry in mud mortar: less than 1/3 of the distance between the adjacent cross walls; For precast concrete wall structures: less than 3/4 of the length of a perimeter wall.

Vertical irregularities typically found in this construction type: Other

Horizontal irregularities typically found in this construction type: Other

Seismic deficiency in walls: The resistance of adobe masonry in this construction type is weakened by the following factors: 1. The openings- due to the following factors:a) the big size of the two windows (1.60 m2) in the main face of the construction. b) The position of the doors in the angles formed by the meeting of walls. c) The great percentage of opening surface (31%) in the front and back walls. 2- The vulnerability of the adobe due to humidity

Seismic deficiency in frames: No buttresses provided at the wall intersections.

Seismic deficiency in roof and floors: The roof is flexible.

For information about how seismic vulnerability ratings were selected see the Seismic Vulnerability Guidelines

Description of Seismic Strengthening Provisions

• Adobe Construction Regulations

• The 1951 Building Code of the Province of San Juan

• Adobe Block Housing in Dry Areas Hugo Giuliani and Jose Herrera Cano

• 1991 National Survey on Population and Housing (INDEC) N18

• Inter-relations Between Architectural Design and Structural Design in High Seismic Risk Areas : Building Level - San Juan San Juan, Argentina 1989