Damp Proof Course (DPC) – Methods of DPC Installation in Construction

In any building, moisture control is essential to maintain its durability, strength, and aesthetics. One of the most widely used methods to prevent moisture penetration from the ground is through the application of a Damp Proof Course (DPC). It acts as a barrier that protects the structure against the harmful effects of rising damp.

Image Credits: Sheridan Products

In this blog post, we'll explore the functions, materials, and various DPC installation methods used in construction, including references to relevant codes like IS 3067:1988 and ACI standards.

 

What is a Damp Proof Course (DPC)?

A Damp Proof Course (DPC) is a horizontal or vertical layer of impermeable material installed in building elements such as walls, floors, or foundations to block the movement of moisture. It is generally applied at the plinth level and plays a crucial role in preventing rising damp from reaching habitable areas.

Definition:

A Damp Proof Course (DPC) is a protective layer installed within masonry walls and floors to resist the passage of moisture by capillary action.

 

DPC Provided at the Plinth Level

 

Primary Function of DPC

The main objective of a DPC is to prevent moisture from moving through the building structure. The three basic ways in which DPC helps are:

• Resisting moisture penetration from below (rising damp).
• Resisting moisture from above (rain penetration or spillage).
• Resisting lateral or horizontal moisture movement (from surrounding soil or adjacent wet zones).
• Enhancing building health and indoor air quality
• Reducing deterioration of plaster, paint, and structural materials
• Minimizing mold growth and associated health risks
• Enhancing lifespan of buildings

Difference Between DPC and Waterproofing

While both are moisture control methods, DPC deals with moisture (dampness), whereas waterproofing handles water under pressure. DPC is rigid and usually installed in dry zones, while waterproofing is more elastic, used in wet zones like roofs, basements, and water tanks.

You can read more on: Difference Between Dampproofing and Waterproofing

Thickness of DPC (as per Standards)

Damp proofing a floor surface

The thickness of DPC varies based on the material used and the standard followed:

India (IS 3067:1988)

• Cement Concrete DPC: Minimum 2.5 cm thick with rich mix (1:1.5:3) and waterproofing admixture.
• Polythene Sheet: Minimum 0.25 mm thickness.
• Bituminous Coating: Two layers, each 1.5 mm thick.

ACI Guidelines

While ACI doesn't specifically define DPC, related practices in ACI 515.2R suggest a minimum membrane thickness of 1.5–2 mm for moisture control in concrete systems.

 

Source (Indian Standard): IS 3067:1988 - Code of practice for DPC

Common DPC Materials

• Cement Concrete (1:1.5:3)
• Bitumen (hot or cold applied)
• Polythene sheets (0.25 mm min)
• Mastic Asphalt
• Metal sheets (lead, copper)
• PVC/HDPE sheets
• Chemical-based admixtures in concrete

 

Methods of DPC Installation in Construction

Here are the 6 key methods of DPC application in building construction:

1. Membrane Damp Proofing (Traditional DPC)

Involves the placement of a damp-proof layer at the plinth level. Materials used include:

• Bituminous felt rolls
• PVC/HDPE sheets
• Polythene sheets (0.25 mm thickness as per IS 2508)

These are laid over a leveled base of concrete and should cover the entire width of the plinth wall.

2. Integral Damp Proofing

Water-repelling admixtures are added directly into the concrete or mortar during mixing. These reduce permeability and improve resistance to moisture ingress.

Common compounds:

• Calcium stearate
• Silicates
• Metallic soaps
• Commercial products like Dr. Fixit Pidiproof, Fosroc Conplast

3. Surface Treatment

Coating the exposed surface with moisture-resistant compounds to block capillary pores.

Materials include:

• Bitumen-based paints
• Lime plaster mixed with water-repellent chemicals
• Silicon-based waterproof coatings

4. Cavity Wall Construction

Cavity walls consist of two masonry skins separated by a gap (usually 50 mm), which acts as a barrier for moisture. The inner wall remains dry even if the outer wall absorbs moisture.

5. Guniting (Shotcreting)

Applying a rich cement mortar (1:3 ratio) under high pressure over a surface using compressed air. It creates a dense, impermeable coating.

Used for repair works, retaining walls, and old structures experiencing damp penetration.

Read On: Shotcrete and Gunite | Difference Between Shotcrete and Gunite | Features

6. Pressure Grouting

• Injecting cement slurry or waterproof grouts under pressure into cracks or porous areas in foundations and walls.
• Used for damp-proofing basements, foundations, and old masonry.

7. Horizontal DPC Installation in New Construction

Steps

• Prepare a level surface above the plinth.
• Apply a layer of rich cement mortar (1:3 ratio).
• Place the DPC material (e.g., bitumen sheet or asphalt layer).
• Ensure complete overlap at joints (minimum 100 mm).
• Apply another mortar layer to sandwich the DPC.

Recommended Thickness

• For bitumen felt: 3 mm
• For mastic asphalt: 20 mm (2 layers of 10 mm each)

8. Vertical DPC Installation

Used in retaining walls, basements, and other exposed substructures.

 
Steps

• Apply waterproof coatings or fix membrane sheets to the vertical surface of walls.
• Overlap horizontal DPC at plinth level.
• Backfill with protective layers such as lean concrete or geotextile wraps.

Cost Analysis of Different DPC Methods

DPC Type	Average Cost (USD/sq.m)	Durability	Recommended Use
Bituminous Felt	5 – 8	10–15 years	Residential buildings
Mastic Asphalt	10 – 15	30+ years	Industrial/commercial buildings
Chemical Injection	12 – 20	20–25 years	Renovation of old buildings
Plastic Sheeting (HDPE)	6 – 9	15–20 years	General purpose

Factors to Consider Before DPC Installation

To ensure longevity and effectiveness, consider the following:

• Site Drainage: Install DPC above the highest water table.
• Material Compatibility: DPC should bond well with masonry and mortar.
• Thermal Expansion: Provide overlaps or joints in flexible materials.
• Continuity: DPC must be continuous at corners and wall junctions.
• Protective Layers: Shield exposed DPC layers from mechanical damage

DPC for Various Parts of a Building

Consequences of Poor DPC Installation

• Efflorescence (white powder deposits)
• Wall dampness and paint peeling off
• Structural decay due to corrosion in reinforcement
• Fungal or mold growth
• Unhealthy indoor conditions

Code References and Standards

IS 3067:1988 – Indian Standard Code of Practice for DPC
IS 2645:2003 – Specification for integral waterproofing
ACI 515.2R-13 – Guide to selecting protective treatments for concrete

Conclusion

A well-executed Damp Proof Course is a foundational requirement in moisture-resistant building construction. Understanding its purpose, types, materials, and proper installation methods can ensure structural longevity, improved indoor air quality, and lower maintenance costs.

Whether you're a civil engineering student, site supervisor, or a construction blogger like on Prodyogi, keeping these essentials in mind will help deliver high-quality, moisture-protected structures.

Read More On: Top 7 Waterproofing Materials for Concrete Roofs