Friday, July 10, 2009

Traditional vs. Modern Construction Practices





Building in the Himalayas poses many challenges. Extreme weather conditions with temperatures reaching over 100° in the summer and below 50° in the winter, and the high possibility of seismic activity. Traditionally, Ladakhi’s had to deal with seismic conditions without the use of concrete and rebar. The first story wall is comprised of granite masonry partly acting as the foundation for the rest of the building and also to protect the structure from corroding during the random occurrences of rain, which can be torrential when accumulated at from high altitudes. Stone used for the first floor also offers more protection when animal live inside during the winter months. There is an elegant connection between the site and the structure when building with stone masonry on the mountain’s granite hillside. Like most masonry construction, windows and doorways are first left as voids, which are then filled with wooden poplar framework. Issued within the rows of stone and earthen blocks are ‘earthquake beams’ which sometimes indicate floor plates but allow for flexibility in the ridged structure. Utilizing the characteristics of compression loads, the earthquake beams are simply connected with lap joints. The earthquake beams can also act as lentils and door headers. An interesting aspect of the buildings is the ability to have large spanning corner window. Being able to span over ten feet is possible due to structural 4x4 lumber mullions. There is typically only one large corner window in a residential building, allowing for natural lighting to bleed into the building. The lentils and headers of doorways, traditionally called char, are often exaggerated. They are built up off the existing support of the headers, allowing to express layers of the char. First an elaborately carved timber is placed spreading out the load of a 12 inch thickness of compressed earth often painted black, the char is then capped with another piece of lumber usually canted down to shed water. Each char has a similar appearance to a Chinese temple roof. To enclose the full envelope of the building, the roof structure is particularly unique to Ladakh. Once building up the walls, gaps are left on the top to place large poplar beams, which range in diameter of 8 to 10 inches. These usually span up to ten feet or are supported by additional interior columns. The Poplar joists are placed no more than two feet apart to allow willow sticks can string atop across the poplar. The next layer of roofing material, laid upon the tightly spaced willow, is a grass that yaks eat which has an oil and strength to it that helps make water resistant. Gravel is then spread out over the grass giving the timber and grass a vapor barrier from the next layer, which is soil. Clay is then applied, which is sandwiched between another layer of soil. After the first shower of rain the soil and clay melt and infuse, tightening the roof plane making it able to shed water. A parapet is formed around with weep holes and scuppers stick out a good two feet from the structure so there is minimal water damage.

With the ability to have cement mix, concrete, and rebar, the structure of modern Ladakhi buildings uses a concrete pier system. Columns are poured every ten to fifteen feet with excess rebar exposed out of the formwork for possible future construction. The floor plates are also poured concrete, which tie the structure together. Then, earthen blocks fill in the gaps between the columns still providing a large thermal mass. The windows are placed in a similar fashion because the masonry construction is still used to build the majority of the walls. Many of the lintels are designed in the local style, making the finished product look much like a traditional building.

2 comments:

  1. It is interesting to read how they traditionally build to withstand earthquakes. The roof treatment is very elaborate. Great photos. Roberta C.

    ReplyDelete
  2. hello

    i want to know more about why is traditional better that modern construction? please

    ReplyDelete