A Paper on “Dhajji Wall Construction”

Ar.Md.Danish, B.Arch (N.I.T. Patna), M.C.P. (I.I.T.Kharagpur), PhD.(pursuing),B.I.T.Mesra

Assistant Professor, Department of Architecture,

Birla Institute of Technology, Mesra (Patna Campus)

E-mail: md7781@gmail.com

Abstract.

“Dhajji” is a Persian word meaning Patchwork quilts in ancient language of carpet

weavers. Because of its visual similarity to the type of patchwork construction in Kashmir,

this term is applied to this type of construction. This type of construction is quite prevalent

in the earthquake prone areas of Jammu & Kashmir. Availability of timber in abundance,

local expertise in construction supported by affordability has made this technology of

construction very popular. During 2005 Earthquake in Jammu & Kashmir, houses made

up of Dhajji technology proved to be more resilient and suffered minimal damage

compared to modern buildings made up of reinforced concrete. In the cool climate, the

main function of the shelter should be to provide thermal comfort to the occupants by

reducing heat loss from the buildings. Apart from pine needle and straw, other materials

which can be added in the infills for Dhajji wall construction are rice, wheat, maize, wool,

cotton etc. which has a high insulation value.

Keywords: Dhajji, Dewari, Insulation, Seismic, Mud-mortar, Dasa, Straw, Joints, Panels.

1. Dhajji Wall: An Introduction

Dhajji dewari (Persian for “patch quilt wall”) is a traditional building type found in the

Himalayan belt of Pakistan and Jammu and Kashmir (Fig.1). Due to its resemblance in the

appearance to quilt patchwork of Persian weavers it is called as “Dhajji”. It is quite prevalent

in the earthquake prone areas of Jammu and Kashmir. Compared to conventional reinforced

construction,”Dhajji” construction is more popular.

Figure 1: Patchwork quilt: "Dhajji" in Persian.

It is quite prevalent in the earthquake prone areas of Jammu and Kashmir. Compared to

conventional reinforced construction,”Dhajji” construction is more popular. It is also referred

to as Brick nogged timber construction. It mainly consists of a braced timber frame where the

spaces between the bracings and frames are filled up with stone and brick masonry laid in

mud mortar. These are generally laid on shallow foundation with stone masonry. Dhajji

buildings are typically 1-4 storeys tall and the roof may be a flat timber and mud roof, or a

pitched roof with timber/metal sheeting.

2. Seismic Attributes

A typical “Dhajji” House is composed of small panels of timber and stone which

resembles a patchwork (Fig.2). Compared to conventional House of Concrete, Dhajji

house is more earthquakes resilient.

Figure 2: Composition of Stone and Timber Infills.

When an earthquake occurs in a conventional house,it usually makes one big

crack,another crack and then the wall get collapsed as the energy is concentrated at a point. In

case of a Dhajji House,there are many small cracks and these small cracks fall out,but the

wall remains as the small panels distribute the energy evenly (Fig.3). When we hit the

stone,either stone breaks or the person get injured,but if a heap of sand is pressed,no harm is

occurred and the grains move away,since the friction breaks down the energy (Fig.3).

Figure 3: Comparison of Seismic forces in Conventional V/S Dhajji House.

Dhajji wall remains strong,only if all the joints are well executed,infills are done properly

and it is well protected from rain water (Fig.4).Small panels distribute the earthquake energy

evenly and the friction between all the panels and the infills break down the energy evenly.

Figure 4: Protective Features of Dhajji Wall.

Figure 5: New Houses being Constructed under Dhajji Dewari technique

after 2005 earthquake in Jammu and Kashmir.

3. Components of Dhajji Wall

Various components of Dhajji Wall are as follows:

3.1. Foundations.

3.2. Plinth Beams (Dasa).

3.3. Frame Structures.

3.4. Joints.

3.5. Roof Truss.

3.6. Walls and Bracings.

3.7. Windows and Doors.

3.8. Infills and Plaster.

3.1.Foundations: A good foundation is prepared with stone and cement mortar.To hold

the mortar with stone properly,anchor bolts made up of plate and hook are placed in

the lower parts of the foundation. Diameter of anchor bolts is ½ inch which is kept 6

feet apart from each other (Fig.6). Foundations shouldn’t come out of ground much

and be kept at a height of 1 foot only.

Figure 6: Diagrammatic representation of Anchor bolts placed inside stone foundation.

3.2.Plinth Beams (Dasa): Main objective while constructing plinth beams is to protect

the foundation from rain and insects and it should be anchored properly with the

foundation.Minimum size of Dasa is kept 4”x4” and it is made up of good quality

timber. Anchoring is done best by using bolts and rebars (Fig.7).

Figure 7: Dasa fixed with solid washer(top),anchoring with bolts and straps(bottom left),

Shade provision for rain water protection(bottom right).

3.3. Framed Structure: A well proportioned framed structure is very essential for the

Dhajji Wall. Main posts of sizes 4”x4” should be 4 feet-6 feet apart.Panels to receive

should be small with the distance between vertical posts be not exceeding 2 feet.

Figure 8: Intermediary gaps shown in Dhajji framed structure.

Figure 9: Detailed out Dhajji framed structure.

3.4. Joints: Dhajji framed structure consist of following types of joints:Dasa extension

joints,Wall joints and Corner joints.

Dasa Extension Joints: For making the Dasa longer, scarf joints or lap joints are

used as shown in the Fig.10.

Figure 10: Dasa Extension Joints using Scarf or Lap Joints.

Wall Joints: To join the posts with the dasa,tenon and mortise joints are

used.Posts can be joined with the dasa with the help of nails or straps as shown

in the Fig.11.

Figure 11: Wall Joints using Tenon and Mortise Joints.

Corner Joints: To make the Corner joints,quarter tenon and half tenon joints

are used as shown in the Fig.12.

Figure 12: Corner Joints using quarter tenon and half tenon joints.

3.5.Roof Truss: Dhajji House consists of two types of roof truss system. They are “onto”

and “against”. When rafters are placed onto the tie beam,it is referred as “onto” and

when the rafters are placed against the tie beam,it is called as “against” roof truss

system (Fig.13).

Figure 13: “Onto” and “Against” Roof Truss System.

3.6. Walls and Bracings: Walls have to be filled up with the diagonal pieces of wood of

thickness 1”-2” and it can be subdivided into small panels in many ways as shown in

Fig.14. Good Dhajji wall has small panels while the wall gets weaker by big

panels,strong diagonals with absence of plinth beams as shown in Fig.15.

Figure 14: Different Styles of Dhajji Walls and Bracings.

Figure 15: Good Examples of Dhajji Wall (Left) and Poor Examples of Dhajji Wall(Right).

3.7.Windows and Doors:It is not advisable to place too many openings in the wall as it

makes the structure weak.Windows and doors should be 2 feet away from the corners

and it should be placed at least 2 feet apart as shown in Fig.16.

Figure 16: Correct Way (Left) and Incorrect Way (Right).

3.8. Infills and Plaster: Cement-Sand infills makes the wall too rigid,due to which the

small panels cannot move individually and absorb the energy.Mud mortar is more

effective,which can be made more elastic by adding pine needles and straw.Mortar

must be same throughout the building. Infills are filled with stone and mud

mortar.Stones used should not be too large and use of small and irregular stones is

preferred (Fig.17).

Figure 17: Correct Way (Left) and Incorrect Way (Right).

4. Dhajji Wall: An alternative to thermal insulation

In cold places, a house must insulate its inhabitants from the outside temperature.

This is achieved by creating walls that are made from materials that insulate well,

often requiring layers of different materials.

A typical “Dhajji House” is composed of small panels composed of stone masonry

and timber of thickness 45-60 cm which have a time lag of 8-9 hours which keeps the

houses warm in winter and cool in summer for maximum part of the year. Apart from

pine needle and straw, other materials which can be added in the infills for Dhajji wall

construction are rice, wheat, maize, wool, cotton etc. which has a high insulation

value. Roofing of Dhajji House is composed of twigs or reeds of sizes 6” to 8” which

when covered by topping of mud or earth leads to thermal insulation providing

comfort to the inhabitants. Apart from the resources available, passive solar heating

can be applied by orienting and clustering the livable spaces towards the sun for solar

heat gain. At the ground floor, cattle are kept to keep the house warm and the livable

spaces are at the first floor as shown in the Fig.18.

Figure 18: Plans,Elevation and Section of a typical Dhajji House

along with the photograph (at top).

Dhajji” House has straw, of K (Thermal Conductivity) Value of 0.09. Straw

bale construction takes space in walls normally reserved for sprayed insulation, rolled

batts or rigid insulating boards filled with stacked straw bales. Straw bales provide far

superior insulation to engineered products and are a recyclable material. It has been

proved by laboratory testing about the earthquake resistant properties of straw bale

construction. PAKSAB (Pakistan Straw bale and appropriate building) is a project

undertaken to provide straw bale homes for the local villagers.

5. References

a) Schacher,Tom and Ali,Dr. Qaisar: Dhajji_English.pdf, DHAJJI CONSTRUCTION

For one and two storey earthquake resistant houses,A guidebook for technicians and

artisans.

b) Langenbach,Randolph: LANGENBACH_KEYNOTE-BNCA-HealthyCities.pdf, Keynote

Address Back to the Future:Lessons from the Past for a more Earthquake-Resistant

City, Conservationtech Consulting, Oakland, California, USA.

c) Schacher,Tom: Schacher-DhajjiLesson(8.3.07)(s).pdf, Basic Training on Dhajji

Construction (Power point Lesson),Version 13.12.06.

d) Sarkar,Ar.Amitava: v60-105.pdf,Adaptive Climate Responsive Vernacular

Construction in High Altitude, World Academy of Science, Engineering and

Technology 60 2011.

e)Kubilây Hiçyılmaz, Jitendra Bothara, Maggie Stephenson: wh100164.pdf,World

Housing Encyclopedia,Housing Report on Dhajji Dewari, an initiative of Earthquake

Engineering Research Institute (EERI) and International Association for Earthquake

Engineering (IAEE).

f) Green Home Guide.com

g)Wikipedia.org.

h)Paksab.org.

i)Webberenergyblog.com.