Friday, 20 April 2012

Step 01 : Identifying approach, process and information to be collected

Our Project brief requires us to prepare manually measured drawings, the basis on which conservation work of the structure and fabric can be directed.

A - Preparation to Work - Reconnaissance survey was conducted of the building, whose base measured 25 mt   by 18mt, having 4 floors (12 spaces in the ground floor, 8 in the first floor, 5 in the second floor, 2 in the third floor and terrace). Based on the drawing provided by the ASI, the spaces were numbered as S1 to S-N, in an anti clock-wise manner (Refer to Photographs- Naming of Spaces and Phasing for Measurements) and a reference diagram was made prior to commencement of  work.  

Naming of Spaces and Phasing for Measurements

B - Identifying Tools - Given that the work was commissioned to only 2 people, a process that provided accurate information yet is time efficient has to be selected. Also, in the absence of standards tools - such as a laser-cross-hair, inclinometers, disto-meter, total station, auto-leveler, digital spirit-level, the method to be resorted had to be manual, with basic tools - spirit level, string, chalk and measuring tape. Therefore, the schedule of work and time-frame had to be revised.  

C - Identifying bearing points and measurements - It was decided by the consultants that the built profile (floor plans) would be drawn by triangulating from an established reference plane. It must be mentioned that the reference planes are normally established outside the structure to be measured. However, in this case, fixed bearing points available are more than 8 meters from the built profile. Over this length, measurements taken are erroneous due to sagging of the tape. Moreover, the site being overtly visited, it is impossible (also requiring permission) to erect a temporary bearing point which will last 6 months (the length of project time). As a result, it was decided that an internal-grid would be established, from which measurements for the internal profile would be acquired and later, from the elevations, the external profile would be drawn. 

D - Phases of work - First, the profile of the interior spaces would be drawn, thereon, smaller details, that measure less than 1 meter i.e. mouldings, interior of niches, details and the profile of the floor, would follow. (Refer to Photographs - Phases of Work - Measured drawing of Floor Plan along established Datum Line)

Phases of Work - Measured drawing of Floor Plan along established Datum Line
Following the profile of the floor, would be the external elevations. For this a vertical reference grid at 2 meters interval would be established and measurements will be taken by a combination of methods - i.e. by triangulating and from rectified photographs (Refer to Photograph- Vertical reference grid along the North Facade).  

Vertical reference grid along the North Facade

E - Tests and Assessments - Based on the reconnaissance survey, a list of tests were also recommended as necessary- 
  • Tell-tales along cracks, separation joints which are possibly active
  • Excavation along at 4 points to assess condition of foundation (before rain)
  • Tests to identify composition and condition of plaster, mortar, bricks, flooring material (at different level and points)
  • Noting of changes in moisture levels, rising dampness etc

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