How to control water penetration in cavity walls?

There are several ways to control water penetration in cavity walls:

1. Properly install a cavity wall membrane: A cavity wall membrane is a waterproof barrier that is installed between the inner and outer walls of a cavity wall. This membrane helps to prevent water from penetrating the wall and causing damage.

2. Ensure proper drainage: Make sure that the cavity wall has adequate drainage to allow any water that does penetrate the wall to drain away quickly. This can be achieved by installing weep holes at the base of the wall and ensuring that any flashing and weep vents are properly installed and maintained.

3. Use water-resistant materials: When constructing cavity walls, use water-resistant materials such as water-resistant bricks, mortar, and sealants to help prevent water penetration.

4. Regular maintenance: Regularly inspect and maintain the cavity wall to ensure that any cracks or damage are repaired promptly. This will help to prevent water from seeping into the wall and causing further damage.

5. Properly seal openings: Ensure that any openings in the cavity wall, such as windows, doors, and vents, are properly sealed to prevent water from entering the wall.

By following these tips, you can help to control water penetration in cavity walls and prevent damage to your building.

Control Measures for Water Penetration in Cavity Walls:

1. Proper Drainage:
- Ensure effective drainage around the building perimeter with gutters, downspouts, and french drains.
- Slope the ground away from the building to divert water.

2. Waterproofing Membrane:
- Install a continuous waterproof membrane at the base of the cavity wall, extending at least 150mm above the finished ground level.
- The membrane should be durable, puncture-resistant, and have suitable properties for the local climate.

3. Cavity Weep Holes:
- Create weep holes at regular intervals near the base of the cavity to allow moisture to drain out.
- Typically, weep holes should be spaced 450-600mm apart and should not be obstructed by insulation or other materials.

4. Cavity Insulation:
- Use closed-cell or hydrophobic insulation that resists moisture absorption.
- Ensure the insulation is properly installed to prevent voids or gaps that can trap water.

5. Mortar and Sealants:
- Use high-quality mortar with low water absorption and good adhesion.
- Seal all joints and openings around windows, doors, and penetrations with appropriate sealants.

6. Flashing and Drip Edges:
- Install flashing at all junctions of roof, walls, and windows to prevent water seepage.
- Use drip edges on windowsills and balconies to divert water away from the cavity.

7. Control Joints and Caulking:
- Provide control joints to relieve stresses in the wall and prevent cracking.
- Seal control joints and cracks with flexible caulking to prevent moisture penetration.

8. Proper Ventilation:
- Allow air to circulate within the cavity to prevent moisture build-up.
- Ensure adequate ventilation by installing vents or air bricks near the top of the cavity.

9. Inspection and Maintenance:
- Regularly inspect the cavity wall for signs of water penetration, such as damp patches or mold growth.
- Address any issues promptly by repairing leaks, replacing damaged components, or applying sealants.

10. Use of Sacrificial Cladding:
- In highly exposed areas, consider using sacrificial cladding materials that absorb moisture, such as rain screen systems, to protect the underlying wall structure.