AN ATTEMPT TO BRIDGE THE GAP BETWEENVERNACULAR AND MODERNITY

LOW COST HOUSE IN AN URBAN ENVIRONMENT

Residence for Shri Sanat Mehta, Constructed in 1994 at Gandhinagar

Shirish Avrani Architect - Planner

Objectives To understand the application of Appropriate technology through live experiment

To have demonstrative effect among other elite class of people –that low cost technology is not only for poor but also for high class of people. It is a “way of life” and not the compromise.

To bridge the gap between vernacular and modernity. A step towards Responsible Architecture

. To identify problems and constrains of :

Convincing the client

Construction process

Contractor

Availability of materials

Finding Laborers – training

Construction time

Maintenance problems.

To experiment innovations like non erodable mud plaster, filler slab etc.

Resistance against natural calamities like earthquakes and cyclones.

To work out actual cost of construction.

To understand and visualized aesthetics of simplicity

Shri Sanatbhai Mehta, a political leader with a deeploving association with the tribals of Gujaratexpressed his view to build a tribal house in his plotat Gandhinagar. The South Gujarat tribal house ishaving a structural grid of 8’ X 11’ wooden postbeam structural system and tiled pitch roof. Thepartition walls are made out of bamboo matting withmud plaster and have flexibility for variousarrangements within a structural grid.

“Traditional Wisdom” -The principal of balance cantilever in roofing system to eliminate the column and making the space free.

Transformation :Adaptation of composite structural system. Wooden columns replaced by precast RCC column- a tribal house of South Gujarat

Alternative solution for replacing wooden columns :AC pipe filled with PCC used as columns

Design ConsiderationsThe principles of vernacular Gujarat tribal architecture were adopted and modified tosuit with urban environment, keeping in mind the life style and values of the owner. Thewooden columns were replaced with cheaper than RCC, circular steel posts (availablefrom scrap of Alang Ship breaking yard). The intermediate floor and sloping roof ofMangalore tiles filler slab was constructed for better insulation and cheaper costs.Walls are made of stabilized mud blocks, with non erodable mud plaster. Doors andwindows were made with pre-cast frames and Nuwud MDF shutters.

The Plot area comprises of 330 sq.m. (15m X 22m) having East-West orientation. Thetotal built-up area provided was 171 sq m with ground floor area of 104 sq m. .The axial entry is provided which leads to central open courtyard, around which allother activities are planned. The bed room is at the rear end for access to South-Westwind direction, along with kitchen and store with a separate service yard are provided.The first floor consists of two bed rooms with attached bath and terrace, with a swingemphasis the main entrance bellow.

The open-to-sky central courtyard

View from first floor- Rose window made from empty bottles

Dining area. The exposed ceiling of Mangalore tills filler slab is visible.

THE CONSTRUCTION PROCESS:1. The Compressed Soil-Block Making:1.1 Tests and MixingRibbon Test to Check For Soil Plasticity: Roll a small handful of soil (with justenough water to make it stick together) into a ribbon of ¼ to ½” diameter. Check howlong it can be rolled before it breaks off. In this case, 4” length is sufficient.

Ribbon test for Soil Plasticity

Optimum Moisture Content Test to Check for Maximum Density: Make a ball of soil of 2 to 2.5” diameter, and drop it from a height of 3.5 to 4’. If the balldoes not fall apart, it indicates too much of moisture cointent, and is therefore notsuitable for block making. If it collapses into a patch of 2’ to 3’ diameter, then moisturecontent is optimum..

Too much of moisture content keeps the soil ball intact

Optimum moisture content –A spread of 2 -3 feet

Stabilizing the Soil: Cement, cement and lime, lime, bituminous tar products andmolasses are some of the stabilizers used to prevent soil softening when it absorbsmoisture.Since soil in Gnadhinagar is red, sandy lloam, 4% of cement was added by volume,over the soil and then it was manually mixed. If mixing is not done thoroughly enough,the blocks will be defective .

Mixing soil withcement stabilizer

1.1 Making the BlocksASTRAM the block-making machine developed by ASTRA (Application of Scienceand Technology for Rural Areas – Bangalore), required 5 people to produce about400 blocks per day, each block being 9” X 7” X 5”. The procedure is as under:

Fill the mould with prepared soil with the help of a scoop;

Staking and drying blocks in the shade.

Curing the blocks for a fortnight

Comparision of good and badblocks:The right hand side block showsthe uniform mix of soil and cement.The left hand side blocks are badblocks in which mixing of earthand cement is not thoroughlydone. This may affect the strengthof the block.

Compressive Strength Test forStabilise Mud Block:

Stack blocks up to a height of 6 feet,keeping the base blocks slightly apart.A crack should be avoided in the baseblock in order to ensure goodconstruction.

2. Erecting Columns

Scrap steel pipes from the Alang Ship-Braking yard were comparatively cheaperthan market ones, besides being strongerand joint less. 4.5” diameter pipes of 4-5mm thickness were used as a supportingstructure.

2.1 FootingsRCC footings were provided for steel pipes,while the rest of the foundation were madeout of conventional brick masonry.

2.2 Fitting the Bars with FootingsBase plates were welded with projectedbars for the column footings. The upperpart of the column was provided withholdfasts, to be inserted into beamsThe erection took only three days, muchless then RCC column.

3. Mangalore Tile Filler Slab Roof The concrete below the ‘Neutral Axis’ of the slab is redundant and can easily bereplaced with other cheaper material like tiles, bricks or coconut shells, on which a thinreinforced slab is cast. The construction steps follow: Framework similar to RCC slab, spread with the engine oil placed on the ground. Manglore tiles immersed in water for 24 hours before use. Reinforcement bars placed at the distance of 18 “ X 12 “ C/c distance (or as

specified in design) in case of 10 feet slab span Main bars (10 mm dia.)were placed along the short span and 8 mm dia. bars along the long span. Negative bars are projected up to 2 feet at the junctions of walls or beams. After that two Mangalore tiles were placed as filler materials, one above the other,in the gap between reinforcement bars A concrete mix of 1:2:3 is manually done and then vibrated to avoid honeycomb. Proper curing for about seven days with water on the slab.

4. Precast Window / Door FramesPre-cast door window frames were used for entire house .The precast memberswere assembled on site and erected along with the walls. Safety bars act asholdfasts. Shutters made out of Nuwud MDF panels..The RCC frames are cost effective and give protection against termite..It is not affected by weather change.

5. Construction of Walls. After erecting steel column and filler slab, the 7” thick mud wall were

constructed with cement stabilized-mud mortar;. 8% cement, by volume (double the amount used for the blocks) was used for the

mortar; because the strength of mortar has to be more than building blocks. One block-volume (9”X7’X5”) is equivalent to volume of three bricks. Besides, no

requirement of a header-stretcher course for bonding, resulted in fasterconstruction

Non Erodable Mud Plaster:Tar primer, produced by the Tiki Tarindustry found to be suitable forstabilizing mud plaster, because it didnot require heat treatment to melt, oraddition of kerosene to dilute.

Primer is soluble in water and easy tomix with mud. It is mixed in the ratio of1:15 by volume.Test:Soil mixed with tar primer does notdissolve, like normal soil , in aglass of water even over a longperiod of time.

Preparation of Wall Surface for Mud plaster: . Water is sprinkled on the wall before

plastering;. Non –erodable mud plaster was applied

with trowel, like a cement plaster.

The creative ‘lipan’is done with cow-dung to finish the walls

Cupboards and built-in beds were constructed out of Kotah Stone. The shutters and sliding drawers were made out of NuWUD

Comparative Cost Analysis Components Conventional

Technology Non-Conventional Technology

Percentage Saving in Cost

Other Advantages

Masonry Work Brick Wall Stabilized Mud Blocks with 5% cement

53 % Better insulation

Biodegradable Energy saving Labour-

intensive Column RCC Column 4.5”dia steel

pipes 11.26 % Fast

installation Slab RCC Mangalore

Tiles RCC Filler Slab

14.41 % Better insulation

Light in weight Saving in cost

in case of RCC structure

Doors Teak Wood frame & Panel shutter

RCC Frame Nuwud Shutter

27.88 % Eco-friendly

Windows -do- -do- 31.34 % -do- Plastering Cement

Plaster Non –erodable Mud Plaster

47.14 % Decorative texture is possible

* The property tax collected by the local authority can be reduced as the cost of the building is comparatively lesser than the conventional structures.

B – ENERGY PERFORMANCE OF A PRE-FAB CONCRETEA – ENERGY PERFORMANCE OF A MUD-BRICK HOUSE

MUD-BRICK HOUSE PRE-FAB. CONCRETE HOUSE

ENERGY PERFORMANCE OF AN IGLOOFIGURE 1 : Daily variation in the inside air temperature of an igloo (atsleeping platform level) under typical arctic temperature condition (FromFitch, J.M. and Branch. D. P., Sci. Am., 203. 6. 1960. Copyright 1960 byScientific American Inc. All rights reserved).

ENERGY PERFORMANCE OF AN ADOBE HOUSEFIGURE 2 : Daily variation in the inside air temperature of an adobe houseunder high daytime temperature condition (From Fitch, J.M. and Branch. D.P., Sci. Am., 203. 6. 1960. Copyright 1960 by Scientific American. Inc. All rightsreserved).

FIGURE 3 : Comparison of the inside air temperatures in a mud-brick room and a prefab concrete room. (A) Mud-brick room (B) Prefab concrete room. (From Cain. A., Afshar. F., and Norton. J., Architectural Design, 4/75, 207.)

ADOBE HOUSEIGLOO

Appreciation letter fromShri Hasmukh Shah,Chairman of GujaratEcology Commission andEx. Chairman of IPCL

Appriciation letter fromEx. Prime minister ShriChandrashekhar Ji.

Thank You

Sustainable architecture is inbuilt in tribal culture since childhood.