How to Install Damp Proof Course (DPC) in Brickwork

🧱 Installing Damp Proof Course (DPC) in Brickwork

What is the purpose of a Damp Proof Course (DPC) in Australian brickwork?

This guide details the correct installation of a Damp Proof Course (DPC) in brickwork, a critical barrier designed to prevent rising damp from ground moisture. Proper DPC installation is essential for the longevity and structural integrity of any masonry structure, complying with AS 3700 Masonry Structures.

What skill level is required to install DPC in brickwork?

Intermediate — Estimated time: ~2-4 hours per 10 linear metres

What tools are essential for DPC installation in brickwork?

What safety precautions are mandatory when installing DPC?

⚠️ Safety

Step-by-Step Guide

How do you prepare the foundation for DPC installation?

1️⃣ Clean and Level Foundation: Ensure the top of the concrete footing or slab is clean, free of debris, and level. Any irregularities greater than 5mm should be rectified with a levelling bed of mortar.

2️⃣ Establish Datum Line: Mark a datum line on the foundation, typically 150mm above finished ground level (FGL), to indicate the DPC height. This ensures compliance with BCA requirements for DPC placement.

3️⃣ Lay First Mortar Bed: Apply a full bed of mortar, approximately 10-12mm thick, along the entire length of the wall where the DPC will be laid. Ensure the bed is level and consistent.

Step 2: Position and Lay the DPC

1️⃣ Cut DPC to Length: Unroll and cut the DPC material to the required lengths, allowing for overlaps at corners and joins. The DPC must extend the full width of the wall, including any render or finish, typically 150mm above FGL.

2️⃣ Lay DPC on Mortar Bed: Carefully lay the DPC material onto the wet mortar bed. Ensure it is flat, without creases or folds. The DPC must project slightly beyond the face of the brickwork to prevent moisture bridging.

3️⃣ Overlap and Seal Joins: At joins, overlap the DPC by a minimum of 150mm and ensure it is fully bedded in mortar to create a continuous barrier. For corners, the DPC should be folded or cut and overlapped to maintain continuity.

Step 3: Lay the Mortar Bed Over DPC

1️⃣ Apply Second Mortar Bed: Immediately apply another full bed of mortar, approximately 10-12mm thick, directly on top of the DPC. This bed will receive the first course of bricks above the DPC.

2️⃣ Ensure Full Coverage: The mortar bed must fully cover the DPC to prevent it from being punctured or damaged by the bricks.

Step 4: Lay Bricks Above DPC

1️⃣ Lay First Course of Bricks: Carefully lay the first course of bricks onto the mortar bed above the DPC. Use a string line and spirit level to ensure they are perfectly level and plumb.

2️⃣ Maintain Mortar Joints: Ensure consistent 10mm mortar joints. Tap bricks gently with a rubber mallet to adjust their position.

3️⃣ Tool Joints: Finish the mortar joints with a jointer or pointing tool for a neat and weather-tight finish.

Step 5: Inspect and Protect

1️⃣ Inspect DPC Continuity: Visually inspect the entire DPC installation to ensure there are no gaps, tears, or areas where it has been bridged by mortar.

2️⃣ Protect DPC: During subsequent construction, protect the exposed DPC from damage. Ensure no debris or mortar falls onto the DPC, creating a bridge for moisture.

3️⃣ Flashing Integration: Where the DPC meets door or window openings, ensure proper integration with flashing details to maintain a continuous moisture barrier. This often requires a stepped DPC.

Common Mistakes to Avoid

Pro Tips

💡 Mortar Consistency: Use a slightly stiffer mortar mix for the bed directly under and over the DPC to prevent it from squeezing out excessively and potentially bridging.

💡 Pre-cut DPC: For long runs, pre-cutting DPC sections can improve efficiency and reduce waste.

💡 Temporary Weight: For windy conditions, place a few bricks on the laid DPC to prevent it from lifting before the next mortar bed is applied.

💡 Visual Check: Always step back and visually inspect the DPC line from a distance to ensure it is straight and level before laying bricks.

💡 Integrated Flashing: For cavity walls, ensure the DPC is integrated with cavity flashings at openings to direct water out of the cavity.

Recommended Tools

🔧 Brick Trowel: Look for a 10-11 inch London pattern trowel for good balance and mortar capacity.

🔧 Spirit Level: A good quality 1200mm box-section level for accuracy over longer runs.

🔧 Line Pins & String Line: Essential for maintaining straight and level courses; opt for durable, non-stretch string.

🔧 Utility Knife with Snap-Off Blades: For clean, precise cuts of DPC material.