Code of practice for anti-termite measures in buildings, Part 1: Constructional measures
1981 Edition

IS 6313 Part 1 (1981) recommends multiple constructional approaches to prevent subterranean termite invasion:

External Measures:

• Installation of metal termite shields or masonry grooves encircling the building to block termite paths.
• Construction of cement concrete aprons around the structure to inhibit soil-to-wall contact.
• Ensuring the metal shields retain their shape for effective function.

Internal Measures:

• Providing a continuous concrete sub-base beneath walls and plinths, including depressed areas such as lift wells and bathrooms.
• Laying concrete flooring atop a coarse sand layer (grain size exceeding 3 mm) to reduce moisture migration.
• Incorporating anti-termite grooves at wall-floor junctions.

Typical layers include a 75 mm thick cement concrete subfloor, 12 mm cement plaster, a 25 mm concrete topping, and lime concrete aprons. Stone or brick superstructures should integrate these termite barriers to ensure a continuous physical obstruction against termite entry.

The standard outlines the following for termite shield installation and upkeep:

Installation:

• Metal termite shields should be placed around the building’s perimeter in termite-prone regions.
• At least 50 mm of the shield must be embedded into the cement concrete sub-floor.
• A 50 mm horizontal projection should extend beyond the external wall face.
• The shield should be bent downward by 50 mm at a 45° angle to deter termite passage.
• Where shields are impractical, especially at entrances, anti-termite masonry grooves should be employed with properly sealed junctions.

Maintenance:

• Regular inspections are vital to maintain the shield’s integrity and shape.
• The embedded portion facilitates easy replacement when necessary.
• Considerations include initial costs, potential maintenance needs, and safety precautions regarding sharp edges.

According to IS 6313 Part 1, the sub-floor concrete should be a dense cement concrete mix with a ratio of 1:3:6 (cement : sand : aggregate). The thickness must be at least 75 mm. This layer is laid over a compacted coarse sand fill with grain sizes greater than 3 mm to reduce moisture migration from the soil. The termite shield embedded in this concrete should have a minimum width of 50 mm, with 50 mm horizontal projection and a 50 mm downward bend at a 45° angle for protection and easy replacement. Additionally, vertical joints between floors and plinth masonry should be sealed with heavy grade coal tar pitch to prevent termite ingress.

IS 6313 Part 1 emphasizes creating continuous, sealed termite barriers at joints and openings to prevent termite intrusion. Vertical joints between floors and plinth masonry must be filled with heavy grade coal tar pitch as per IS 216-1961. Where termite shields cannot be installed, anti-termite masonry grooves are provided at entrances or doorways, ensuring tight junctions with shields to block termite access. The combined use of metal shields, masonry grooves, concrete aprons, continuous concrete sub-bases, and coarse sand layers under flooring form an integrated defense system sealing all potential termite entry points.

Recommended site preparation under IS 6313 Part 1 includes:

• Conducting a stake test by burying wooden stakes of termite-susceptible species at 150 mm depth spaced one meter apart and examining them after several months for termite activity.
• Ensuring proper site grading and drainage to avoid water stagnation around the foundation.
• Removing all organic debris such as roots, leaves, stumps, and wooden remnants near foundation areas.
• Eliminating the topsoil layer rich in decaying organic material where necessary.
• Avoiding burial of organic matter near foundations.
• Using a coarse sand layer beneath concrete flooring to reduce soil moisture.
• Providing continuous concrete sub-base under walls and plinths.
• Installing metal termite shields or masonry grooves around the building.
• Sealing joints between floor and plinth masonry with coal tar pitch to block termite entry.

These combined measures reduce termite attraction and create physical barriers against infestation.