Code of practice for setting out of buildings

IS 11134: Scope & Key Specifications Summary

Scope (Clause 2.0 & 6.1)

• Defines accuracy requirements for primary points used as reference in building layout.
• Applies to building projects where these points guide positioning of structures.

Permissible Deviations (Clause 2.12 & 11.3)

• Deviations apply equally in positive and negative directions.
• Accuracy of primary points is maintained independently of national reference system errors.

Accuracy Principles (Clause 6.1 & Fig. 2)

• Accuracy expressed for angles, lengths, and levels.
• Use of a free net system connecting primary points to official coordinate systems via a reference point and direction.
• Ensures building points are set out with controlled deviations.

Diagram: Free Net Reference System

graph LR
  A[Official System] --> B[Reference Point (10)]
  B --> C[Primary System Reference Point]
  C --> D[Secondary System Baselines]
  D --> E[Building Main Points]
  E --> F[Position Points (e.g., column center lines)]

This standard ensures precise building layout by controlling permissible deviations and referencing systems systematically.

IS 11134: Key Definitions & Permissible Deviations for Setting Out

Definitions (Clause 2.0, 2.12)

• Primary Points: Reference points forming the basis of building layout.
• Secondary Points: Points set out from primary points (e.g., baselines).
• Position Points: Points like center lines of columns.
• Permissible Deviation (E): Allowed limit of deviation, both positive and negative, equal in magnitude.

Permissible Deviations (Clause 8.2)

Formulas for Permissible Deviations

• Distance between points:

[ E = \pm K \sqrt{L} \quad \text{(mm)} \quad \text{for } L \geq 5,m ]

[ E = \pm 2K \quad \text{(mm)} \quad \text{for } L < 5,m ]

• Angle between two lines (dependent):

[ E_{\theta} = \pm 0.067 K \sqrt{L} \quad \text{(degrees)} ]

or in gons:

[ E_{\theta} = \pm 0.075 \frac{K}{\sqrt{L}} \quad \text{(gons)} ]

Notes:

• L: Length in meters of the shorter side of the angle or distance.
• K: Constant based on accuracy requirement.
• Permissible deviations ensure layout accuracy aligned with project needs.

flowchart LR
    A[National Reference System] --> B[Primary Points]
    B --> C[Secondary Points (Baselines)]
    C --> D[Position Points (Center Lines)]
    D --> E[Building Elements]

This hierarchy shows the reference flow from national system to building elements via setting out points.

IS 11134: General Principles - Key Formulas, Tables & Specifications

1. Permissible Deviations (Clause 11.3, Table 11.2)

2. Setting Out & Levelling (Clause 11.3)

• Instruments must be checked for accuracy and stability before first use.
• Re-check instruments frequently during work.

3. Permissible Deviation Concept (Clause 2.12)

• Deviations (E) are symmetrical: ±E.
• Applies to distances, angles, and vertical levels.
• Visualized as a tolerance band around the true value (see Fig. 2 in code).

4. Principles of Setting Out (Clause 6.1)

• Primary points define the reference framework for buildings.
• Accuracy requirements depend on the relative position of these points.
• Coordinates determined from a network of traverses linked to official coordinate systems.

5. Summary Diagram: Setting Out Network

graph LR
A[Official Reference Point] --> B[Primary System Reference Point]
B --> C[Secondary System Baselines]
C --> D[Main Building Points]
D --> E[Position Points (e.g., column centers)]

Note:

• Use metric, woven metallic, or glass fibre tape measures as per specifications.
• Accuracy of building points is independent of errors in the national coordinate system due to proper referencing.

This concise summary aligns with IS 11134's general principles on accuracy, permissible deviations, and setting out methodology.

IS 11134: Reference Systems and Bench Marks – Key Points

Accuracy Requirements (Clause 11.2.1)

Note: Contract documents may specify stricter tolerances.

Reference Systems (Clause 6.1 & 6.2)

• Primary System: Framework of primary points adjusted as a whole (least squares method).
• Secondary System: Derived from primary system; used for detailed setting out.
• Connection to Official System: Preferably via a single reference point and direction to avoid propagating inaccuracies.

Methods for Establishing Primary Points

• Loop traverses
• Redundant resection
• Intersection
• Simultaneous polar method
• Anblock method (see Fig. 5 in code)

Summary Diagram of Reference Systems

graph TD
  A[Official System] -->|Reference Point & Direction| B[Primary System]
  B --> C[Secondary System]
  C --> D[Building Main Points]
  D --> E[Position Points (e.g., column centers)]

Additional Notes

• Verticality deviation (plumbline deviation) and angle deviations are controlled as per IS 11134 figures.
• Use metric, woven metallic, or glass fibre tape measures as per specifications.
• Accuracy of primary points depends on adjustment of entire framework, not isolated points.

This ensures reliable, traceable, and precise setting out for construction projects.

IS 11134: Primary Points and Position Levels - Key Specifications

1. Primary Points (Clause 2.1)

• Established by precise measurement.
• Referenced to national/municipal or agreed coordinate systems.
• Serve as reference points for setting out secondary points.
• Coordinates derived from a network of traverses or triangulation nets.
• May be locally adjusted but maintain overall system integrity.

2. Accuracy Requirements (Clause 6.1)

• Primary points must meet strict relative position accuracy for building placement.
• Accuracy expressed as permissible angular and linear deviations.
• Errors in primary points propagate to secondary points and building layout.

3. Permissible Deviations (Clause 7.3)

• Secondary points have defined tolerance limits relative to primary points.
• Deviations depend on project scale and precision needed.

4. Secondary System (Clause 7.2)

• Secondary points form grids or base lines for detailed setting out.
• Derived from primary points, used for building components like column centerlines.

Typical Accuracy Parameters (from IS 11134 and general practice):

Conceptual Diagram of Point Systems

graph TD
  A[National/ Municipal Reference System]
  B[Primary Points]
  C[Secondary Points (Site Grid/Base Lines)]
  D[Building Main Points (Columns, Walls)]
  A --> B
  B --> C
  C --> D

Summary

• Primary points: High-accuracy reference points tied to official coordinate systems.
• Secondary points: Derived from primary points, used for detailed layout.
• Permissible deviations ensure building accuracy and depend on project scale.
• Use traverses/triangulation nets for establishing primary points.
• Maintain accuracy by controlling angular and linear deviations per IS 11134.

IS 11134: Accuracy Requirements for Primary Systems

Key Points from Clauses:

• Clause 6.1 & 7.1: Accuracy is specified for:

  • Relative positions within the same secondary system.
  • Between different secondary systems.
  • Between primary and secondary points.

• Primary points serve as reference points for building placement.

Permissible Deviations for Angles (Fig. 2):

• Angular deviations depend on the order of the network.
• Typical permissible angular deviation:
  [ \Delta \theta = \frac{30''}{\sqrt{L}} ] where (L) = length of traverse in kilometers (approximate guideline).

Accuracy Specifications:

Network Setting Out (Fig. 3 Concept):

• Primary system connected to official coordinate system via:
  • One reference point.
  • One reference direction.
• Secondary systems (baselines) set out from primary system.
• Position points (e.g., column center lines) set relative to secondary baselines.

Additional Notes:

• Levels (Clause 11.1): Benchmarks must maintain relative vertical accuracy within ±5 mm for primary benchmarks.
• Use metric, woven metallic, or glass fibre tape for length measurements to maintain accuracy.

graph TD
  A[Official Coordinate System]
  B[Primary System]
  C[Secondary System]
  D[Position Points]

  A -->|Reference Point & Direction| B
  B -->|Baselines| C
  C -->|Set out| D

Summary:
Maintain strict angular and linear tolerances for primary points as per IS 11134, ensuring building layout accuracy by referencing official coordinate systems through primary and secondary networks.

IS 11134: Setting Out of Secondary Points — Key Formulas & Specifications

1. Secondary System Overview (Clause 7.2)

• Secondary points serve as reference points for detailed setting out of buildings.
• They can be combined two-by-two to form base lines.
• Secondary points + main points = secondary system for the building.
• Established from primary points via intersection, resection, polar methods.
• Accuracy of secondary points depends on proper primary system setup.

2. Permissible Deviations (Clause 7.3.3)

• For distances between points in different secondary systems:

  [ \text{Permissible deviation} = K \times L \quad \text{(in mm)} ]

  • (L) = distance between points (m)
  • (K) = accuracy constant (from Clause 8, depends on project accuracy requirements)

3. Accuracy & Personnel

• Primary system setup: Qualified surveyors/engineers
• Secondary system setting out: Engineers or surveyors with building survey knowledge
• Position points: Usually by site foreman

Summary Table: Permissible Deviation

(Refer Clause 8 for exact values per project)

flowchart TD
    A[Primary Points] --> B[Secondary Points]
    B --> C[Base Lines (Secondary System)]
    C --> D[Position Points (Columns, Walls)]

Note: Always coordinate primary system connection with local survey authorities to ensure compliance with official coordinate systems.

IS 11134 - Accuracy Requirements for Position Points

Key Points from Clauses 5, 6, 7, 8:

• Clause 5.1: Accuracy decreases with the number of measurements due to error propagation. Minimize operations to maintain precision.
• Clause 6.1: Primary points serve as reference for building placement; their accuracy is critical.
• Clause 7.1: Specifies accuracy between points within the same secondary system, between secondary systems, and between primary and secondary points.
• Clause 8.1: Defines accuracy requirements for relative positions of position points.

Accuracy Specifications:

Note: Values vary based on project precision needs and measurement methods.

Error Propagation Formula:

[ \sigma_{total} = \sqrt{\sum_{i=1}^n \sigma_i^2} ]

• (\sigma_i): Standard error of each measurement step
• (n): Number of measurement steps

Setting Out Principles:

• Use a free net connected to official coordinate systems via one reference point and direction.
• Limit inaccuracies by minimizing polygons and measurement series.
• Control setting out of corner and baseline points to avoid misfits in building components.

Diagram: Free Net Connection Concept

graph LR
  A[Official Coordinate System]
  B[Primary System Reference Point]
  C[Primary System Reference Direction]
  D[Secondary System Baselines]
  E[Main Building Points]
  F[Position Points (e.g., Column Centers)]

  A --> B
  B --> C
  C --> D
  D --> E
  E --> F

Summary:
IS 11134 emphasizes controlling measurement operations and maintaining strict accuracy for primary and secondary points to ensure precise building layout and avoid construction issues. Use minimal measurement steps and connect secondary systems properly to primary references.

IS 11134: Marking and Protection of Points – Key Specifications

1. Marking of Primary Points (Clauses 6.5, 10.4)

• Primary points must be precisely marked (e.g., punch marks).
• Place primary points outside the working zone to avoid displacement.
• Transferred points should be marked immediately after measurement to prevent movement.

2. Accuracy & Permissible Deviations (Clause 8.2)

• Permissible deviation for distance (L in meters):

  [ \pm K \sqrt{L} \text{ mm} ]

• For (L < 5,m):

  [ \pm 2K \text{ mm} ]

• Permissible deviation for angle between two lines:

  [ \pm 0.067 K \sqrt{L} \text{ radians} \quad \text{or} \quad \pm 0.075 K \sqrt{L} \text{ gons} ]

3. Reference System & Network

• Primary points are referenced from a free net connected to official coordinate systems.
• Accuracy of main points is independent of inaccuracies in national/municipal systems.

graph LR
A[National Reference Point] --> B[Primary System Reference Point]
B --> C[Secondary System Baselines]
C --> D[Main Building Points]
D --> E[Position Points (e.g., column centers)]

Summary:
Mark primary points precisely and protect them from displacement. Use the constant (K) and distance (L) to calculate permissible deviations for setting out, ensuring accuracy appropriate to the construction type.

IS 11134: Measurement and Check Procedures - Key Points

1. Marking (Clause 10.4)

• Immediately mark transferred points after measurement to prevent displacement.

2. Check Measurements (Clauses 2.8, 10.5)

• Check measurements must be independent and use instruments with equal or better accuracy.
• Optical plumbings must be verified with instruments of similar accuracy.

3. Instrument Accuracy & Re-checking (Clause 11.3)

• Instruments must be checked thoroughly before first use and re-checked frequently.
• Adjust if necessary to maintain accuracy and stability.

4. Permissible Deviations of Difference in Level (Table 11.2)

5. Distance Measurement (Clause 4.1)

• Use measuring tape conforming to IS 1269-1964.
• Correct measurements for temperature, sag, slope, and tension.
• Use a tension device with the tape.
• For check measurement, use a different tape conforming to the same IS.

Correction Formula for Tape Measurement

[ L_c = L_m + \Delta T + \Delta S + \Delta Sl + \Delta Te ]

Where:

• (L_c) = Corrected length
• (L_m) = Measured length
• (\Delta T) = Correction for temperature
• (\Delta S) = Correction for sag
• (\Delta Sl) = Correction for slope
• (\Delta Te) = Correction for tension

flowchart LR
    A[Measurement] --> B[Mark Transferred Point]
    B --> C[Check Measurement]
    C --> D{Accuracy OK?}
    D -- Yes --> E[Use Data]
    D -- No --> F[Re-check Instrument]
    F --> G[Adjust Instrument]
    G --> C

This flow ensures accuracy and reliability in setting out and leveling operations.

IS 11134: Permissible Deviations and Tolerances

Key Formulas

• Permissible deviation of position point distance:

[ E = \pm K \sqrt{L} \quad \text{(mm)} ]

• For L < 5 m:

[ E = \pm 2K \quad \text{(mm)} ]

• Permissible deviation of angle between two lines:

[ E_\theta = \pm 0.067 K \sqrt{L} \quad \text{(degrees)} ]

or

[ E_\theta = \pm 0.075 \frac{K}{\sqrt{Zgon}} \quad \text{(gon)} ]

where:

• (L) = length in meters (shorter side of angle)
• (K) = constant from Table 1 (accuracy class)

Table 1: Constant (K) for Accuracy Classes

Permissible Deviations of Difference in Level (Clause 11.3)

Notes

• Deviations are ± and symmetric.
• For setting out, levelling instruments must be checked and adjusted regularly.
• Contract documents may specify different tolerances if required.

graph TD
A[Specified Distance L] --> B{L < 5 m?}
B -- Yes --> C[Permissible Deviation = ± 2K mm]
B -- No --> D[Permissible Deviation = ±

IS 11134 - Errors and Their Minimization: Key Points

1. Instrument Accuracy & Checks (Clause 11.3)

• Instruments must be checked for accuracy and stability before first use.
• Frequent re-checking is mandatory.
• Permissible deviations in difference of level (mm):

2. Causes of Errors (Clause 6.6)

• Centering errors due to:
  • Instrument errors (optical plummets, targets)
  • Poorly defined points (rough marks, large diameters)

3. Permissible Deviations in Setting Out (Clauses 2.12 & 8.2)

• Position point deviation formula:

[ \text{Permissible Deviation} = \pm K \sqrt{L} \quad \text{(mm)} ]

• For ( L < 5 , m ):

[ \pm 2K \quad \text{(mm)} ]

• Permissible angular deviation:

[ \pm 0.067 K \sqrt{L} \quad \text{(radians)} \quad \text{or} \quad \pm 0.075 K \sqrt{Zgon} ]

• Values of K based on accuracy:

Summary

• Always check instruments and points to minimize errors.
• Use permissible deviations based on application type.
• Apply formulas for distance and angular deviations with constant (K).

flowchart TD
    A[Start Setting Out] --> B[Check Instrument Accuracy]
    B --> C{Is Instrument Accurate?}
    C -- No --> D[Adjust & Re-check]
    C -- Yes --> E[Define Points Clearly]

Use of Grids and Coordinate Systems (IS 11134: Clause 2.4)

Key Concepts:

• Grid Definition: Two sets of parallel horizontal lines at right angles forming a coordinate system.
• Types of Grids:
  • Site Grid: Used on large sites with many parallel building lines to simplify setting out.
  • Structural Grid: Centre lines of structural elements referenced to base lines to locate structural elements.
  • Location Grid: Used by planning authorities to legally define boundaries, streets, etc., with high accuracy.

Specifications & Procedures

• Primary System:

  • Framework of primary points adjusted simultaneously (least squares method).
  • Methods: loop traverses, redundant resection, intersection, simultaneous polar, anblock method (Fig. 5).
  • Avoid connecting site system to official system by only one reference point.

• Secondary System:

  • Reference points and directions chosen for internal accuracy.
  • Consult authorities before setting out.

• Accuracy:

  • Location grids are considered error-free per legal requirements.
  • Internal building accuracy ensured by referencing one point and one direction per grid square.

Important Notes:

• Vertical transfer of points and plumbline deviation must be controlled (Clause 2.4:10).
• Adjustment of primary system must be done as a whole.
• Specialist precision work requires custom methods.

Example: Anblock Method (Primary System Adjustment)

graph LR
A[Instrument Station 1] --> B[Free Net Point 1]
A --> C[Free Net Point 2]
D[Instrument Station 2] --> B
D --> C
E[Instrument Station 3] --> B
E --> C

Summary Table: Grid Types

For detailed setting out, always consult the relevant authority and use least squares adjustment for primary points.

IS 11134: Special Cases and Notes - Key Points

1. Setting Out (Clause 8.3)

• For values of K ≤ 5, setting out shall follow Clauses 4.1 and 4.2.
• Applies to typical building construction; precision machinery setting out requires special treatment.

2. Accuracy Requirements (Clause 6.1 & 7.3)

• Primary points form the reference for building placement.
• Permissible deviations for secondary points and angles are specified to ensure accuracy.
• Deviation limits depend on project scale and precision needed.

3. Permissible Deviations for Angles (Fig. 2)

• Defines allowable angular errors during setting out.
• Ensures structural elements align within tolerance.

4. Network Types & Reference Systems

• Free net: Coordinates derived from traverse networks.
• Connected to official coordinate system by:
  • One reference point
  • One reference direction
• Accuracy of building points is independent of national system errors.

Summary Table: Permissible Deviations (Example)

Diagram: Free Net Setting Out Concept

graph LR
  A[Official Reference Point] --> B[Primary System Reference Point]
  B --> C[Secondary System Baseline]
  C --> D[Main Building Points]
  D --> E[Position Points (e.g. column centers)]
  A --> F[Reference Direction]

Note: Always refer to IS 11134 Clauses 4.1, 4.2, 6.1, 7.3, and 8.3 for detailed formulas and tolerances.

IS 11134 - Key Specifications & Tables for References and Bibliography

1. Accuracy Requirements (Clause 6.1)

• Defines permissible deviations in positioning primary points (reference points for buildings).
• Uses a free net connected to official coordinate systems by one reference point and one direction.
• Ensures internal accuracy independent of national system errors.

2. Permissible Deviations for Angles

• Refer to Fig. 2 (not shown here) for graphical representation.
• Accuracy expressed as allowable angular deviations during setting out.

3. Grids (Clause 2.4)

• Site Grid: For many parallel building lines; simplifies setting out.
• Structural Grid: Center lines of structural elements, referenced to base lines.
• Location Grid: Legal boundaries and axes, accuracy per local laws.
• Setting out uses one reference point and one reference direction per grid square.

4. Vertical Transfer Accuracy (Clause 11.2.1)

5. Notes

• Consult appropriate authorities for reference points and accuracy requirements.
• Contract documents may specify stricter tolerances.

flowchart LR
    A[Official Coordinate System]
    B[Primary System Reference Point]
    C[Primary System Reference Direction]
    D[Secondary System Baselines]
    E[Structural Grid (Center Lines)]
    F[Building Elements]

    A --> B
    B --> C
    C --> D
    D --> E
    E --> F

This diagram shows the hierarchical relationship from official coordinate systems down to building elements.

Summary: IS 11134 emphasizes accuracy in setting out via primary and secondary reference systems, permissible deviations for angles and levels, and structured grid systems for precise building placement.