Report #: 136

Report Date:

Country: GUATEMALA

Housing Type:

Housing Sub-Type:

Author(s): Matthew A. French

Last Updated:

Regions Where Found: Buildings of this construction type can be found in Guatemala, mostly in the highlands. The traditional construction is bajareque, which is similar to Wattle and Daube. Vertical and horizontal timber poles hold a core of stone and/or mud, and the outside is plastered with mud mix. Adobe use in urban areas is less prevalent than it has been historically. There are some historic towns, such as Antigua, which are almost completely composed of adobe dwellings relying on this romanticized past of adobe architecture to draw tourists. This type of housing construction is commonly found in both rural and urban areas. As noted, there is a large existing building stock of adobe in urban centres, but few new buildings. The exception to this is in Guatemala city, where 'satellite settlements' on the urban fringe use adobe for economic reasons. Thin reinforced concrete frames with red fired brick infill walls is the emerging preferred method in these urban centres.

Summary: This very small building doubles as a home and workplace. The homeowner weaves products such as hats, clothes and mats for a living. The building functions as a showroom for her products by the day and as her house for rest at night. Three months before the site visit, the house was washed away by Hurricane Stan that hit the Central American region. Massive rainfall led to landslides in the Lago Antilian area, where the site is located. Her house was destroyed and this is the new one constructed. This case study is characteristic of new adobe construction in the Guatemala today. Timber dowels at the top brick course help to secure the ring beam or timber roof framing to the walls. For economic reasons, the roof is corrugated iron, but the long-term plan is to place clay tiles directly over top for their thermal and aesthetic properties. This case study is testament to the trying and tenuous living conditions which the occupants face. It demonstrates that even though un-reinforced adobe fails, many have no option but to replace it with structurally fragile adobe once more.

Length of time practiced: More than 200 years

Still Practiced: Yes

In practice as of:

Building Occupancy: Mixed residential/commercial

Typical number of stories: 1

Terrain-Flat: Typically

Terrain-Sloped: Off

Comments:

Currently, this type of construction is being built. In the Solola district, adobe is commonly used still, because the transport

Plan Shape: Square, solid

Additional comments on plan shape: The building is well configured with respect to its plan geometry and symmetry; it is simply one square room. The building has two doors, 700mmx1800mm. There are no windows.

Typical plan length (meters): 3.1-6

Typical plan width (meters): 2.9-6

Typical story height (meters): 2.2

Type of Structural System: Masonry: Earthen/Mud/Adobe/Rammed Earth Walls: Rammed earth/pile construction

Additional comments on structural system: Lateral load-resisting system: Adobe shear walls act as the lateral resisting structure in both directions. The blocks measure 200mm wide, 400mm long and 100mm deep. The timber framed roof is a flexible diaphragm, and hence will play minimal role in resisting or transferring lateral loads.

Gravity load-bearing system: The adobe walls also act as the gravity load bearing structure. Gravity loads are transferred from the roof to the ring beam then to the wall and through to the ground.

Gravity load-bearing & lateral load-resisting systems:

Typical wall densities in direction 1: >20%

Typical wall densities in direction 2: >20%

Additional comments on typical wall densities: Wall density is unknown.

Wall Openings: The building has two doors, 700mmx1800mm. There are no windows.

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

Modifications of buildings: There are no structural modifications. The exterior plaster and clay roof tiles are added incrementally as funds permit. This will provide increased thermal comfort and aesthetic value. There are plans to build a timber addition on the east side.

Type of Foundation: Shallow Foundation: Rubble stone, fieldstone strip footing

Additional comments on foundation:

Type of Floor System: Metal beams, trusses, or joists supporting light flooring

Additional comments on floor system: Compacted earth and cement mix

Type of Roof System: Wooden roof, unknownRoof system, other

Additional comments on roof system: wood planks or beams that support slate, metal, asbestos-cement or plastic corrugated sheets or tiles

Additional comments section 2: Due to the limited availability of flat land in the area, the houses are constructed very close together. When separated from adjacent buildings, the typical distance from a neighboring building is 0.5 meters.

Who is involved with the design process?: Other

Roles of those involved in the design process: The NGO's working in the area and help that has come to 'clean up' may have had some trained building staff. The likelihood is that no practising architect or engineer was involved in this building.

Expertise of those involved in the design process: Traditional knowledge and methods generated the design and construction. These people are not involved.

Who typically builds this construction type?: Other

Roles of those involved in the building process:

Expertise of those involved in building process:

Construction process and phasing: The construction of this type of housing takes place in a single phase. Typically, the building is originally designed for its final constructed size. With adobe construction a 'base' house is built as one complete project and over time other rooms (not always of adobe) are added as needed.

Construction issues

Is this construction type address by codes/standards?: No

Applicable codes or standards:

Process for building code enforcement:

Are building permits required?: No

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:

Typical problems associated with this type of construction:

Who typically maintains buildings of this type?: BuilderOwner(s)

Additional comments on maintenance and building condition:

Unit construction cost: US $ 35/ m2.

Labor requirements: The house took two people two months to build.

Additional comments section 3:

Damage patterns observed in past earthquakes for this construction type: Wall - 45# shear cracking under in-plane lateral loads occurs. This cracking increases vulnerability for wall collapse under face loads.

Roof and floors - The roof fails to hold the top of the walls in place. Wall displacement becomes too large and dislodges roof support, which in turn leads to roof collapse.

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.

Additional comments on structural and architectural features for seismic resistance: This building is well maintained as it is new , but many others are not. The workmanship is very good. The blocks and mortar joints are even, course heights level and block mix consistent. This is to be commended.

Vertical irregularities typically found in this construction type: No irregularities

Horizontal irregularities typically found in this construction type: No irregularities

Seismic deficiency in walls: The adobe walls are too thin and brittle to resist lateral in plane and face loads. Adobe is strong in compression, but very weak in tension.

Earthquake-resilient features in walls: Lintels have suitable anchorage back into the walls.

Seismic deficiency in roof and floors: The roof is too flexible and insufficiently connected to the walls to enable it to work as a rigid diaphragm

Earthquake resilient features in roof and floors: The roof is light- weight minimizing risk of injury

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

Additional comments on seismic strengthening provisions: The bamboo strengthening scheme is not used in Guatemala, but is presented in this report as an option for making adobe buildings safer generally.

Has seismic strengthening described in the above table been performed?: Bamboo: Yes, it has been implemented in Peru with successful structural results but unsuccessful local adoption of the concept. The system is not used in Guatemala. Timber ring beam: These are common now, but often limited finances ensure they are out of reach for many in Guatemala. 'Improved Adobe': Some of the principles, such as small openings and walls, are used but others such as buttresses are not evident.

Was the work done as a mitigation effort on an undamaged building or as a repair following earthquake damages?: All work was done as part of mitigation efforts.

What has been the performance of retrofitted buildings of this type in subsequent earthquakes?: Bamboo: The performance of buildings has been successful with only slight cracking and full collapse averted. Timber ring beams: These have been successful in reducing full collapse of the structure.

Guidelines for Earthquake Resistant Non-engineered Construction IAEE National Information Center of Earthquake Engineering, IIT Kanpur, India 2004

An Improved Means of Reinforcing Adobe Walls - External Vertical Reinforcement Dowling,D., Samali,B. & Jianchun,L. Sismo Adobe, Lima, Peru 2005

Adobe and Rammed Earth Buildings: Design and Construction McHenry,P. John Wiley and Sons, Canada 1984

Building with Earth: a Handbook Norton,J. Intermediate Technology Group, Warwickshire 1986

Earthquake database search, www.ngdc.noaa.gov National Geophysical Data Centre, Date accessed: 15/3/2006