Code of practice for design and construction of floors and roofs with prefabricated brick panel

IS 14142: Scope - Key Specifications & Tables

Scope:

• Covers prefabricated brick panels and partially precast concrete joists for roofing and flooring.
• Specifies steel reinforcement requirements, concrete mix, and structural detailing.

Key Table: Steel Reinforcement for Joists (Spacing 1200 mm c/c)

• Concrete: M15 grade, 35 mm thick.
• Max aggregate size: 12 mm.
• Stirrups spacing reduced at ends for shear.

Important Notes:

• Reinforcement can be mild steel or deformed bars.
• Some bars can be reduced if proper handling is ensured.
• Refer to IS 432 (steel bars), IS 456 (plain and reinforced concrete), IS 875 (loads), and related waterproofing codes listed in Annex A.

flowchart LR
    A[Prefabricated Brick Panel Roof] --> B[Concrete M15, 35mm thick]
    B --> C[Steel Reinforcement]
    C --> D[Bottom Bars]
    C --> E[Middle Bars]
    C --> F[Top Bars]
    C --> G[Stirrups]

For detailed design, refer to Clause 4.2.2 and **Table

IS 14142: Elements of Roof/Floor – Key Specifications & Reinforcement Table

Typical Section (Fig. 1)

• 35 mm thick M15 cement concrete topping (max aggregate size 12 mm)
• Prefabricated brick panel supported on precast RCC joists
• 1:4 cement-sand packing mortar (10-15 mm thick)
• Reinforcement mesh: 2 layers of 96 mm Ø bars in each panel, spaced max 1250 mm

Reinforcement for Joists (Spacing 1200 mm c/c) – Clause 4.2.2

Note: Stirrups can be reduced to 6 mm if proper handling is ensured.

References for Design & Materials

• IS 432 (Part 1): Mild steel reinforcement bars
• IS 456: Plain and reinforced concrete code
• IS 875 (Part 2): Imposed loads on buildings
• IS 14143: Prefabricated brick panel & precast joist specification

flowchart TB
    A[Precast RCC Joist] --> B[Prefabricated Brick Panel]
    B --> C[1:4 Cement-Sand Mortar]
    C --> D[

IS 14142 - Design Criteria Summary

1. Reinforcement (Clause 3.3)

• Use reinforcement as per IS 456: 1978 (Plain and Reinforced Concrete).
• Steel bars: Mild steel or deformed bars as specified.

2. Loads for Design (Clause 4.1.2.1)

3. Steel Reinforcement Requirements for Joists (Clause 4.2.2, Table 1)

• Spacing: 1200 mm c/c typical.
• Bottom reinforcement: Varies with clear span (1800 mm to 4200 mm), e.g. 2-8 mm dia bars for 1800 mm span, up to 3-16 mm dia bars for 4200 mm span.
• Middle reinforcement: Typically 1 No. 6 mm dia bar.
• Top reinforcement: Typically 1 No. 6 mm dia bar.
• Stirrups: 6 mm dia at 130 mm c/c (100 mm c/c at ends for longer spans).

Note: ¢ = diameter symbol; bars can be mild or deformed steel.

IS 14142: Design of Prefabricated Brick Panels

Key Specifications (Clause 4.1 & 4.1.1)

• Support Condition: Panels are designed as simply supported between two joists or between a joist and a wall.
• Application: Used in floors and roofs combined with partially precast concrete joists.

Design Considerations

• Loadings: Include self-weight of panel, finishes, imposed loads, and any additional loads as per IS 875.
• Span (L): Distance between supports (joists/walls).
• Panel Thickness (t): Typically ranges between 50 mm to 75 mm depending on design.
• Material Strength: Use brick strength and mortar properties as per IS 1077 and IS 2250.

Basic Flexural Design Formula (Simplified)

[ M_u = \frac{w L^2}{8} ] Where:

• ( M_u ) = Ultimate bending moment
• ( w ) = Uniform load per unit length (kN/m)
• ( L ) = Span length (m)

Shear and Bearing

• Check shear at supports and ensure bearing length on joists/walls is adequate to prevent crushing.

Typical Table: Panel Thickness vs Span (Indicative)

Construction Notes

• Ensure proper curing of brick panels.
• Use recommended mortar mix (1:4 cement:sand).
• Provide adequate reinforcement in joists as per IS 456.

flowchart LR
    A[Joist/Wall Support] --> B[Prefabricated Brick Panel]
    B --> C[Joist/Wall Support]
    B --> D[Loads: Self-weight, Imposed]
    D --> E[Calculate Bending Moment & Shear]
    E --> F[Check Strength & Deflection]
    F --> G[Design Joist & Panel Thickness]

Summary: Design prefabricated brick panels

Design of Partially Precast Joists (IS 14142 - Clause 4.2)

Design Stages (Clause 4.2.1)

• Stage I: Precast, lifting, transportation, handling
• Stage II: Placing, accidental loading during construction
• Stage III: Final loading condition

Loads for Each Stage (Clause 4.2.1.1)

Design Approach (Clause 4.2.2)

• Joist designed as T-beam with 35 mm flange thickness at Stage III.
• For Stages I & II, design as partially precast beam.
• Reinforcement for normal loading (spacing 1200 mm c/c) from Table 1 (refer IS 14142 for detailed reinforcement values).

Key Formula for Stage III T-Beam Design

[ M_u = 0.87 f_y A_s (d - \frac{A_s f_y}{f_{ck} b}) ]

Where:

• (M_u) = Ultimate moment
• (f_y) = Yield strength of steel
• (A_s) = Area of tension reinforcement
• (d) = Effective depth
• (f_{ck}) = Characteristic compressive strength of concrete
• (b) = Width of flange (effective width)

Summary Diagram

flowchart LR
    A[Stage I: Precast Handling] --> B[Stage II: Construction Loading]
    B --> C[Stage III: Final Loading]
    C --> D[Design as T-beam (35 mm flange)]
    B --> E[Design as Partially Precast Beam]

Note: Always verify reinforcement from Table 1 in IS 14142 for joist spans and loading conditions.

IS 14142: Transportation and Handling Key Points

Transportation (Clause 5.1)

• Prefabricated brick panels: Transport vertically, leaning against truck/trailer side.
• Handling: Panels handled horizontally using suitable rope slings; avoid jerks and vibrations.
• RC Joists: Lift with slings at ends; max overhang on carriage = 1/5 of joist length.

Design Stages for Panels (Clause 4.1.2)

Panels must be designed for:

1. Stage I: Precasting, lifting, transportation, handling.
2. Stage II: Placing and accidental construction loads.
3. Stage III: Final service loads.

Reinforcement Table for Joists (Clause 4.2.2)

• Note: ¢ = diameter of bars; spacing c/c = center to center.
• Reinforcement can be reduced if handling is proper.

Handling Tips

• Use rope slings for horizontal lifting of panels.
• Avoid jerks and vibrations during transport.
• Joists must be secured with max overhang = L/5.

Summary Mermaid Diagram

flowchart TD
    A[Precast Panel] --> B{Transport}
    B -->|Vertical| C[Lean against truck side]
    B -->|Horizontal| D[

IS 14142: Construction Procedures for Precast RCC Roofs

Key Specifications & Tables

1. Steel Reinforcement for Precast RCC Joists (Clause 4.2.2)

For joist spacing 1200 mm c/c, reinforcement varies by clear span (mm):

Note: "+" indicates reinforcement can be reduced to 6 mm dia if proper handling ensured.

2. Concrete & Panel Details

• Concrete Grade: M15 (1:2:4 mix)
• Panel Thickness: 35 mm (prefab brick panel)
• Max. Aggregate Size: 12 mm
• Mortar: 1:4 cement-sand packing, 10-15 mm thick

3. References for Construction Practice

• IS 432: Mild steel bars specification
• IS 456: Code of practice for plain and reinforced concrete
• IS 875 (Part 2): Design loads for buildings (imposed loads)
• IS 1346, 4365, 9918: Waterproofing codes
• IS 14143: Specification for prefabricated brick panels and precast joists

Summary Diagram of Reinforcement Layout

graph LR
A[Bottom Reinforcement] --> B

IS 14142: Floor/Roof Finish - Key Points

1. Timing & Materials (Clause 7.1)

• Floor/roof finishes applied after concrete hardening.
• Waterproofing essential; refer to:
  • IS 1346:1991 – Bitumen felts waterproofing
  • IS 4365:1967 – Bitumen mastic application
  • IS 9918:1981 – Glass fibre tissue reinforced bitumen
  • IS 3036:1992 – Lime concrete waterproof finish

2. Reinforcement for Joists (Clause 4.2.2, Table 1)

• ϕ = bar diameter in mm.
• Stirrups generally at 130 mm c/c, reduced to 100 mm c/c at ends for longer spans.

3. Typical Roof Section (Fig. 1)

• 35 mm thick M15 cement concrete topping.
• Prefab brick panel supported on precast RCC joists.
• Mortar packing 10-15 mm thick.
• Max aggregate size: 12 mm.

Summary Diagram

graph TD
  A[Precast RCC Joist] --> B[Prefab Brick Panel]
  B

Load Considerations for Different Stages (IS 14142)

Design Stages & Loads

Important Notes:

• For joists at Stage II, joists are propped at two points at the largest span; design span = 1/3 of total span.
• Imposed loads refer to live loads as per IS 875 (Part 2):1987.
• Accidental load in Stage II is half the imposed load of Stage III if no better data exists.

Summary Table:

flowchart LR
    A[Stage I: Precast & Handling]
    B[Stage II: Construction]
    C[Stage III: Final Loading]

    A -->

IS 14142 - Reinforcement Requirements Summary

Key Specifications (Clause 3.3 & 4.2.4)

• Reinforcement steel as per IS 456:1978 (Plain and Reinforced Concrete).
• Clear cover for longitudinal reinforcement: 25 mm.
• Use Mild steel or Deformed bars depending on location and handling.

Reinforcement for Precast RCC Joists (Table from Clause 4.2.2)

• Ø = bar diameter in mm.
• Stirrups spacing is closer at ends for shear reinforcement.
• Some bars can be reduced to 6 mm if handling is proper.

Additional Notes

• Concrete mix: M15 (1:2:4) with max aggregate size 12 mm.
• Refer IS 456 for detailed bar bending and anchorage.
• Use deformed bars for better bond except where mild steel specified.

flowchart LR
    A[Clear Span] --> B{Span Range}
    B --> |1800-2100| C[Bottom: 2-8Ø mild steel]
    B --> |2400-2700| D[

Seismic Strengthening per IS 14142 & Related Codes

• Reference Standard: For seismic strengthening of roofs/floors with precast units in high seismic zones, follow IS 4326:1993 (Earthquake Resistant Design).

• Key Points from IS 14142:

  • Precast roofs/floors must be strengthened as per IS 4326.
  • Reinforcement steel as per IS 456:1978.
  • Table for steel reinforcement in precast joists (spacing 1200 mm c/c):

• Strengthening Tips:

  • Provide adequate anchorage and lap lengths as per IS 456.
  • Use deformed bars for better bond.
  • Ensure proper handling to reduce reinforcement where possible.

• Additional IS Codes for Strengthening:

  • IS 4326:1993 for seismic detailing.
  • IS 456:1978 for reinforcement specifications.
  • IS 14143:1994 for precast brick panel and partially precast concrete joist specifications.

Conceptual Diagram of Reinforced Precast Joist Section

graph TD
A[Top Reinforcement] --> B[Precast RCC Joist]
C[Middle Reinforcement] --> B
D[Bottom Reinforcement] --> B
E[Stirrups] --> B
B --> F[Brick Panel Roof]

Summary:
For seismic strengthening of precast floors/roofs, follow IS 4326 detailing, use reinforcement as per IS 456 and IS 14142 tables, and ensure proper anchorage and handling to maintain structural integrity in seismic zones.

IS 14142: Material Specifications Summary

1. Reinforcement Steel

• As per Clause 3.3, use reinforcing steel conforming to IS 456:1978.
• Mild steel and deformed bars are specified with diameters (¢) indicated in Table 1 for various spans.

2. Reinforcement Requirements for Joists (Table 1, Clause 4.2.2)

• Spacing: 1200 mm c/c typical.
• Clear Span Range: 1800 mm to 4200 mm.
• Reinforcement Details:

• Note: "+" bars can be reduced if proper handling is ensured.

3. Concrete & Other Materials

• Concrete Grade: M15 with max aggregate size 12 mm.
• Roof Finish: Prefabricated brick panels with 35 mm thick M15 cement concrete topping.
• Mortar: 1:4 cement-sand packing mortar, 10 to 15 mm thick.

4. Referenced IS Codes

• IS 432 (Part 1): Mild steel & medium tensile steel bars.
• IS 456:1978: Plain and reinforced concrete code.
• IS 875 (Part 2): Design loads (imposed).
• IS 14143: Specification for prefabric

Panel Placement and Joint Filling (IS 14142: Clause 6.3)

• Mortar Bedding: Lay a 6 mm thick layer of cement-sand mortar (1:4) over joists/walls before placing brick panels.
• Brick Orientation: Keep frogs (indentations) of bricks facing upward during casting and placement.
• Panel Bearing: Minimum bearing length on joists/walls = 40 mm.
• Panel Gap: Leave a gap of 20 to 40 mm between adjacent panels.
• Joint Filling: Fill gaps with M15 concrete using a wooden strip placed below joist to hold concrete in place. The strip is removed by sliding horizontally after concrete sets.

Typical Section Details (Fig. 1 Summary)

• Panel thickness: 35 mm M15 concrete topping.
• Mortar packing: 6 mm thick 1:4 cement-sand mortar.
• Reinforcement: Refer to Clause 4.2.2 Table for joist reinforcement based on span (spacing 1200 mm c/c).

Reinforcement Table Snippet (for joists at 1200 mm spacing)

Summary Diagram (Panel Placement & Joint Filling)

flowchart LR
    A[Joist/Wall] --> B[6 mm Cement-Sand Mortar Layer]
    B --> C[Place Brick Panel (Frogs Up)]
    C --> D[Leave 20-40 mm Gap Between Panels]
    D --> E[Fill Gap with M15 Concrete]
    E --> F[Use Wooden Strip Below Joist]
    F --> G[Remove Strip Horizontally After Filling]
``

IS 14142: Drainage and Waterproofing Key Points

Waterproofing Specifications (Clause 7.1)

• Waterproofing must be applied after in-situ concrete hardening.
• Use relevant IS codes for guidance:
  • IS 1346:1978 — Waterproofing of roofs with bitumen felts.
  • IS 4365:1967 — Application of bitumen mastic for waterproofing.
  • IS 9918:1981 — In-situ waterproofing with glass fibre tissue reinforced bitumen.
  • IS 3036:1992 — Laying lime concrete for waterproofed roof finishes.

Reinforcement for Precast RCC Joists (Clause 4.2.2 - Table 1)

• For joist spacing 1200 mm c/c, reinforcement varies by clear span (1800 mm to 4200 mm).
• Typical reinforcement includes:
  • Bottom bars: 2-8 mm to 3-16 mm diameter bars depending on span.
  • Middle bars: Usually 1 No. 6 mm to 1 No. 10 mm bar.
  • Top bars: 1 No. 6 mm bar standard.
  • Stirrups: 6 mm bars at 130 mm c/c (100 mm c/c at ends for longer spans).

Typical Section for Brick Panel Roof

• 35 mm thick M15 cement concrete.
• Prefab brick panel with 1:4 cement-sand packing mortar.
• Precast RCC joists spaced max 1250 mm.

Summary Table: Reinforcement for Joists (Spacing 1200 mm c/c)

IS 14142: References and Annexes Summary

1. Key Table: Steel Reinforcement for Joists (Clause 4.2.2)

• ¢ = diameter of bars (mm)
• Stirrups spacing reduces at ends for higher shear.
• Reinforcement can be reduced if proper handling is ensured (+).

2. Annex A: List of Referred Indian Standards

3. Annex B: Technical Committee Composition

• Includes experts from Ministry of Urban Development, CPWD, DDA, BIS, Structural Research Centres, Housing Authorities, and Industry Representatives.
• Ensures standard is developed with multidisciplinary inputs.