Understanding Damp Proof Course (DPC) in Construction

A Damp Proof Course (DPC) is a barrier installed in walls to prevent moisture from rising through the structure by capillary action, which is known as rising damp. It is a crucial component in construction to ensure the longevity and habitability of a building.

Let's analyze each option provided regarding the properties and placement of a Damp Proof Course (DPC):

Analysis of Options

• Option 1: It is measured in the cubic meter.

  Damp Proof Course is typically a horizontal layer or sheet material with a specific thickness. Its quantity is commonly measured based on the area it covers, in square meters (\(m^2\)). While it has a volume, measuring it in cubic meters (\(m^3\)) is not the standard practice for DPC installation quantity. Linear measurement (running meter) might sometimes be used for specific strip applications, but volume measurement is incorrect for the main DPC layer.

  Therefore, this option is incorrect.

• Option 2: It is measured in running meter.

  While running meter (linear meter) could potentially be used to specify the length of a DPC strip of a standard width and thickness, the most common and accurate method for measuring the quantity of DPC material is by its area in square meters (\(m^2\)), as it's a layer applied over an area. Running meter isn't universally incorrect in specific narrow applications, but area is more standard for general DPC work. However, compared to the other options, we need to evaluate which statement is definitively correct or incorrect in a typical context.

• Option 3: It is not provided at sills of doors.

  The primary Damp Proof Course is installed continuously at the plinth level (usually about 150 mm above ground level) across the full width of the wall to stop rising damp from the foundation. Door openings interrupt the continuous wall. While damp proofing is crucial around openings, the main continuous DPC layer typically runs below the level of door sills. Special detailing is used around door openings to ensure continuity with the main DPC layer and prevent damp penetration at the junction, but a continuous DPC layer is not typically placed *at* the sill itself like it is in the main wall run.

  This statement aligns with standard construction practice regarding DPC placement at door openings.

  Therefore, this option is correct.

• Option 4: It is provided for half the width of the plinth wall.

  For a Damp Proof Course to be effective in preventing rising damp across the entire wall, it must cover the full width of the plinth wall. Providing DPC for only half the width would leave the other half unprotected, allowing moisture to rise through that portion of the wall.

  Therefore, this option is incorrect.

Conclusion

Based on the analysis of each option, the statement that Damp Proof Course is not provided at sills of doors is the correct one in the context of where the main, continuous DPC layer is typically located and how openings are treated.

Revision Table: Damp Proof Course Facts

Additional Information on Damp Proof Course (DPC)

Damp Proof Course is a vital layer in building construction. Its failure can lead to significant issues like plaster damage, peeling paint, timber decay (affecting skirting boards, floor joists), and unhealthy living conditions due to persistent dampness and mold growth.

Common materials used for DPC include:

• Bituminous felt
• Plastic (polyethylene) sheets
• Courses of impervious bricks
• Cement concrete (often with waterproofing admixture)
• Mastic asphalt

Proper installation is key. The DPC must be continuous without any breaks. Where walls meet or corners occur, the DPC sheets must be properly lapped or joined to maintain continuity. Similarly, where the DPC in a wall meets a DPC in a floor, they must be linked to form a continuous barrier against moisture.