Guidelines for selection and development of the site for building in hill areas, Part 2: Selection and development

IS 14243 Part 2: Scope & Key Specifications

1. Scope (Clause 4.2)

• Applies to building site selection and slope stability in hilly areas.
• Building sites generally on slopes ≤ 30° for safety.
• Temporary non-residential buildings allowed on slopes up to 45°.
• Cutting heights limited per soil/rock type (Table 2).

2. Stable Cut Slopes (Clause 6.1, Table 1)

3. Maximum Height of Cutting (m) (Clause 4.2, Table 2)

4. Safety Factors for Slopes (Clause 8.2, Table 8)

Summary Diagram: Slope Stability Considerations

graph TD
    A[Building Site Selection] --> B{Slope Angle}
    B -->|≤ 30°| C[Suitable for Buildings]
    B -->|30

Referenced Standards in IS 14243 (Part 2): 1995

Key Indian Standards Adjunct to IS 14243 (Part 2):

Stability of Slopes (Clause 6.1, Table 1)

Important Notes

• Strict inspection by municipal engineers is mandatory in hilly regions to prevent failures on uphill sides affecting downhill buildings.
• BIS copyright restricts reproduction but allows use of essential details for implementation.
• Use referenced IS codes for earthquake resistance, foundation design, and structural safety in hilly terrain.

graph LR
A[IS 14243 Part 2] --> B[IS 1893: Earthquake Design]
A --> C[IS 12070: Shallow Foundations on Rock]
A --> D[IS 13063: Structural Safety on Rock Foundations]

This structure ensures safe design and construction in hilly areas with slope stability and foundation safety per Indian standards.

IS 14243 Part 2: Stability of Slopes - Key Specifications

1. Stable Cut Slopes (Clause 6.1, Table 1)

2. Factors of Safety for Slopes (Clause 8.2, Table 8)

3. Maximum Heights of Cutting (Clause 4.2, Table 2)

Additional Notes:

• Slope Selection: Prefer hillside slopes ≤ 30° for building sites.
• Protection Works: Breast walls or minor protection improve slope stability drastically.
• Steep Slopes: Temporary non-residential buildings may be allowed up to 45° slope.
• Surface Protection: Refer IS 1893 (earthquake), IS 12070 & IS 13063 for foundation and structural safety on slopes.

graph TD
A[Soil/Rock Type] -->

IS 14243 Part 2: Site Selection Criteria for Building in Hill Areas

Key Guidelines & Specifications

• Slope Criteria (Clause 4.2):

  • Building sites should ideally be on hill slopes ≤ 30° (safe angle of repose).
  • Temporary non-residential buildings allowed on slopes up to 45°.
  • Stable slopes >30° possible with in-situ rock and favorable discontinuity dips.

• Maximum Height of Cutting (Table 2):

• Stable Cut Slopes (Table 3, Clause 6.1):

Summary:

• Select sites with ≤30° slope for stability.
• Follow cutting height limits per soil/rock type.
• Adopt stable cut slopes as per soil/rock and protection availability.
• Detailed site-specific investigations recommended for critical structures.

flowchart TD
    A[Select Hill Site] --> B{Slope ≤ 30°?}
    B -- Yes --> C[Site Stable for Building]
    B -- No --> D{Temporary Non-Residential?}
    D -- Yes --> E[Slope ≤ 45° Allowed]

IS 14243 Part 2: Geotechnical Investigations - Key Points

1. When to Conduct Detailed Geotechnical Investigations (Clause 4.13)

• Building area > 500 m²
• Rock bed dip > 20°
• Presence of fissures, cracks, faults, voids
• Heterogeneous rock with shear zones or soft seams
• Foundation area infested with long roots
• Significant seepage or erosion at foundation

2. Parameters to Investigate (Clause 5.1)

• Soil/Rock type: Weathered/intact, bedding dip, drainage, shear planes, cracks, vegetation
• Overburden thickness & soil strata
• Shear parameters of in-situ soil (governing failure)
• Drainage pattern & permeability tests
• Identification of slip zones

3. Stable Cut Slopes (Clause 6.1 - Table 3)

Additional Notes:

• Competent geotechnical engineers must certify stability of site and slopes post-development.
• Site development in hilly areas can cost 30-40% of total building cost due to geotechnical works.

flowchart TD
    A[Start: Building Site Selection] --> B{Building area > 500 m²?}
    B -- Yes --> C[Conduct detailed geotechnical investigations]
    B -- No --> D[Check rock dip > 20°]
    D -- Yes --> C
    D -- No --> E[Check fissures, cracks, shear zones, roots, seepage]
    E

Terrace Development - Key Points from IS 14243 Part 2

1. Height and Slope of Cutting (Clause 6.1 & Table 1)

• Height of cutting: Minimum possible, not exceeding limits in Clause 3.2.
• Slope of cutting: Use slopes from Table 1 or stable slopes observed locally.

2. Stability Factors (Clause 8.2, Table 8)

3. Additional Specifications

• Slope stability analysis is essential for safe terrace design (Clause 8.1).
• Stilt foundations recommended to minimize slope cutting and related issues (Clause 9).
• Surface protection for high steep cut slopes is necessary (Clause 10).

Summary Diagram of Terrace Development Considerations

graph TD
  A[Terrace Development] --> B[Cutting Height: Minimum]
  A --> C[Slope of Cutting]
  C --> D[Use Table 1 Slopes]
  A --> E[Stability Factors]
  E --> F[Static & Dynamic Factors (Table 8)]
  A --> G[Foundation Type]
  G --> H[Stilt Foundations in Hilly Areas]
  A --> I[Surface Protection]

**Use these guidelines to ensure safe, stable terrace development in hilly terrain per IS 142

IS 14243 Part 2: Stepped Terrace Development - Key Points

1. Height & Slope of Cutting (Clause 6.1)

• Height of cutting: Minimum possible; must not exceed limits in Clause 3.2.
• Slope of cutting: Follow Table 1 or stable slopes observed nearby.

2. Soil & Rock Suitability (Clause 7.2)

• Avoid stepped terraces on:
  • Soil mixed with boulders.
  • Loose/weathered soft rocks.
  • Badly fractured rocks.
  • Rocky zones with dip > 20° outward/downward.

3. Stability Factors (Clause 8.2)

• Ensure these minimum factors for foundation safety.

4. Advantages of Stepped Terrace (Clause 7.1)

• Minimizes hill cutting & deforestation.
• Reduces cost of site and slope protection.
• Less load on valley side reduces foundation failure risk.

Summary Diagram: Stepped Terrace Suitability Check

flowchart TD
    A[Start: Site for Stepped Terrace] --> B{Soil/Rock Type}
    B -->|Suitable| C{Slope Dip ≤ 20°?}
    B -->|Unsuitable| D[Do Not Develop Stepped Terrace]
    C -->|Yes| E[Check Cutting Height & Slope]
    C -->|No| D
    E --> F[Ensure Safety Factors (Static & Dynamic)]
    F --> G[Proceed with Stepped Terrace Development]

Note: Refer to IS 14243 Part 2 Table 1 for exact slope values and Clause 3.2 for cutting height limits.

IS 14243 Part 2: Stability of Slopes and Stepped Terraces

Key Specifications & Factors of Safety (Clause 8.2)

• Static factor ensures safety under normal conditions.
• Dynamic factor accounts for seismic or dynamic loads.

Stable Cut Slopes (Clause 6.1, Table 1)

Important Notes:

• Slope cutting height should be minimized.
• Factor of safety should be checked for individual slopes and entire terraces.
• For stepped terraces, ensure drainage and surface protection to avoid instability.
• Use stilt foundations for eco-friendly construction on slopes (Clause 9).

Summary Diagram: Slope Stability Factors

graph TD
    A[Slope Type] --> B[Soil/Talus/Debris]
    A --> C[Rock Slopes]
    B --> D[Static FoS = 1.5]
    B --> E[Dynamic FoS = 1.2]
    C --> F[Static FoS = 1.2]
    C --> G[Dynamic FoS = 1.0]

For detailed design, refer to IS 14243 Part 2 clauses 6.1, 8.1, 8.2 and

IS 14243 Part 2: Stilt Foundations for Ecofriendly Construction

Key Specifications:

• Stilt foundations are ideal for hilly terrain to avoid extensive slope cutting and related instability.
• Superstructure materials: wooden/steel frames with fibre-glass, aluminium, or GI sheet roofing.
• Walls: PVC sheets or similar lightweight cladding.
• For tall buildings: RCC stilt frames with RCC columns at varying levels.

Stability & Safety Factors (Clause 8.2):

Stable Cut Slopes (Clause 6.1):

Design Notes:

• Calculate safe bearing capacity including seismic increase per IS 1893:1984.
• Foundations must prevent settlement (see IS 13063:1991, IS 12070:1987).
• Stilt foundations reduce environmental impact by minimizing slope disturbance.

flowchart TD
    A[Hilly Terrain] --> B[Use Stilt Foundations]
    B --> C[Lightweight Superstructure]
    B --> D[RCC Stilt Frames for Tall Buildings]
    A --> E[Slope Stability Check]
    E --> F{Slope Type}
    F -->|Soil| G[Safety Factor: 1.5 Static, 1.2 Dynamic]
    F -->|Rock| H[Safety Factor: 1.2 Static, 

Surface Protection of High Steep Cut Slopes (IS 14243 Part 2)

Key Points:

• Avoid high steep cuts; they require costly protection and are prone to slips during monsoon due to water percolation along joints and fissures (Clause 10.0).
• Main aim: Provide proper drainage to reduce water infiltration and lubrication of weak planes.

Stable Cut Slopes (Clause 6.1, Table 1)

Maximum Heights of Cutting (Clause 4.2, Table 2)

Safety Factors for Slopes (Clause 8.2, Table 8)

Summary of Protection Measures:

• Use breast-walls, retaining walls, or minor protection works to steepen slopes safely.
• Ensure adequate surface and subsurface drainage (e.g., drains, weep holes) to prevent water build-up.
• Limit cut heights as per soil/rock type.
• Prefer stable slope angles

IS 14243 Part 2: Construction Precautions & Quality Control in Hilly Regions

Key Specifications & Precautions (Clauses 10.9, 10.10)

• Drainage: Restore natural drainage; dispose water to streams via lined/unlined drains.
• Ground Slope: Provide proper slope after hill cutting/filling to prevent water ingress and slope failure.
• Soak Pits:
  • Avoid in front/rear of buildings on slopes >30°.
  • Locate soak pits at building sides with minimum 2 m clearance from foundation.
• Retaining Walls:
  • Max height: 4 m.
  • Foundation slope: 3:1 towards hillside.
  • Avoid successive retaining walls >5 m due to collapse risk.
• Site Selection: Avoid slopes steeper than 30° for permanent buildings. Temporary non-residential up to 45° allowed.
• Vertical Cracks: Indicate slope instability; require detailed investigation.

Table 2: Maximum Heights of Cutting

Quality Control

• Strict inspection by municipal engineers.
• Ensure foundation safe bearing capacity (IS 1893:1984 for seismic).
• Prevent settlement (IS 13063:1991, IS 12070:1987).
• Regular monitoring for slope stability and cracks.

flowchart TD
    A[Site Selection < 30° slope] --> B[Proper Drainage Restoration]
    B --> C[Proper Ground Slope]
    C --> D[Soak Pit Location (Side, 2m clearance)]
    D --> E[Retaining Wall (Max 4m, 3:1 slope foundation)]
    E --> F[Regular Inspection & Quality Control]
    F --> G[Slope Stability Monitoring]

This ensures safety, prevents slope failure, and controls construction quality in hilly terrains