A cavity tray is a component used in the construction of cavity walls to prevent the ingress of water into the building envelope.
It is typically made of durable material, such as metal or plastic, and is designed to be placed at critical junctions in the cavity wall to create a continuous barrier that directs water out of the wall and away from the building.
Types of cavity trays
Standard Cavity Trays:
- Corner Cavity Tray (C)
- Junction Cavity Tray (J)
- Gable Abutment Cavity Tray (G)
- Parapet Wall Cavity Tray (P)
- Bay Window Cavity Tray (B)
- Lean-To Cavity Tray (L)
- External DPC Cavity Tray (E)
Specialized Cavity Trays:
- Secret Gutter Cavity Tray (Q)
- Stop-End Cavity Tray (X)
- Weep Hole DPC Cavity Tray (W)
Cavity Tray Materials:
- Rigid cavity trays
- Flexible cavity trays
- Pre-formed cavity trays
- Continuous cavity trays
Cavity Tray Shapes:
- L-shaped cavity trays
- Stepped cavity trays
- Circular cavity trays
Brief introduction of each cavity tray
Standard Cavity Trays:
1. Corner Tray (C)
It is a building component installed in the corner of a cavity wall to prevent water ingress.
It is designed to collect water that penetrates through the outer leaf of the wall and directs it out of the wall via weep holes.
2. Junction Tray (J)
It is a building component installed at the junction between two walls to prevent water ingress.
It is designed to collect water that penetrates through the outer leaf of the walls and directs it out of the wall via weep holes.
3. Gable Abutment Tray (G)
It is a building component installed at the junction between a gable wall and a pitched roof to prevent water ingress.
It is designed to collect water that penetrates through the outer leaf of the walls and directs it out of the wall via weep holes.
4. Parapet Wall Tray (P)
It is a building component installed at the junction between a parapet wall and a flat roof to prevent water ingress.
It is designed to collect water that penetrates through the outer leaf of the wall and directs it out of the wall via weep holes.
5. Bay Window Tray (B)
It is a building component that is installed around the perimeter of a bay window to prevent water ingress.
It is designed to collect water that penetrates through the outer leaf of the wall and directs it out of the wall via weep holes.
6. Lean-To Cavity Tray (L)
It is a building component installed at the junction between a lean-to roof and a main roof to prevent water ingress.
It is designed to collect water that penetrates through the outer leaf of the walls and directs it out of the wall via weep holes.
7. External DPC Tray (E)
It is a building component that is installed at the base of a cavity wall to prevent rising dampness.
It is designed to act as a barrier to moisture and prevent it from rising from the ground into the wall.
Specialized Cavity Trays:
1. Secret Gutter Tray (Q)
It is a building component that is installed at the eaves level of a pitched roof to allow for the installation of a secret gutter.
2. It is designed to collect water that penetrates through the outer leaf of the wall and direct it out of the wall via weep holes.
Stop-End Tray (X)
It is a building component that is installed at the end of a run of cavity trays to prevent water from entering the cavity at that point.
It is designed to collect water that penetrates through the outer leaf of the wall and directs it out of the wall via weep holes.
3. Weep Hole DPC Tray (W)
It is a building component that combines a DPC (damp proof course) with weep holes to prevent water ingress and dampness.
It is designed to allow water to drain out of the cavity and prevent moisture from rising from the ground into the wall.
Cavity Tray Materials:
1. Rigid Trays
These are building components made of materials such as rigid plastic or metal. They are designed to be durable and provide a long-lasting barrier against moisture ingress.
These are often used in construction applications where durability and resistance to deformation are important.
2. Flexible Trays
These are building components made of materials such as flexible plastics or rubber. They are designed to be flexible and conform to the shape of the wall or roof, ensuring a tight seal and preventing moisture ingress.
These are often used in construction applications where flexibility and ease of installation are important.
3. Pre-formed Trays
These are building components that are pre-formed to a specific shape or size. They are designed to be easy to install and ensure a tight seal against moisture ingress.
These are often used in construction applications where consistency and speed of installation are important.
4. Continuous Trays
These are building components that are installed continuously along the length of a cavity wall or roof.
They are designed to provide a continuous barrier against moisture ingress and ensure that any water that penetrates the outer leaf of the wall or roof is directed out of the building via weep holes.
These trays are often used in construction applications where high levels of protection against moisture are required.
Cavity Tray Shapes:
1. L-shaped Trays
These are building components that are shaped like the letter L, and they are used in construction applications where walls intersect at a 90-degree angle.
They are designed to fit into the corner formed by the two walls and prevent water ingress.
2. Stepped Trays
These are building components that are designed for use in construction applications where the cavity wall has a step or change in level.
They are designed to follow the profile of the wall and ensure that water is directed out of the building via weep holes.
3. Circular Trays
These are building components that are designed for use in construction applications where a circular or curved wall is present. They are designed to follow the curve of the wall and prevent water ingress.
These are often used in the construction of bay windows or rounded corners on buildings.
Size of cavity tray
These are available in a range of standard sizes, with the most common sizes being 225mm x 225mm, 225mm x 300mm, and 225mm x 450mm. These sizes are typically suitable for most cavity wall applications.
However, in some cases, larger or smaller cavity trays may be required. For example, if the cavity wall is particularly thick, a larger tray may be necessary to ensure adequate protection against water penetration.
Importance of cavity tray
These are essential for buildings in areas with high rainfall or where the structure is exposed to driving rain, which can penetrate the wall through gaps in the mortar, around openings, or through the porous brickwork.
By redirecting water away from the wall and into the drainage system, these trays help to prevent dampness, mold growth, and other problems associated with water ingress.
Benefits of using a cavity tray system
1. Prevents Water Ingress
It acts as a barrier against water ingress by redirecting water away from the building envelope and into the drainage system. This helps to prevent dampness, mold growth, and other problems associated with water damage.
2. Increases Building Durability
It can help to extend the lifespan of buildings by preventing water from penetrating the structure and causing damage to the building fabric.
3. Improves Indoor Air Quality
By preventing moisture and dampness, these trays help to improve indoor air quality and reduce the risk of respiratory problems and other health issues associated with mold growth.
4. Enhances Energy Efficiency
It can help to reduce energy consumption by preventing cold air from entering the building through gaps in the wall.
5. Aesthetically Pleasing
It can be designed to blend in with the building facade and are available in a range of colors and finishes to match the building’s design.
6. Easy to Install
These are easy to install and can be customized to suit different building configurations, making them a popular choice among builders and contractors.
7. Low Maintenance
This is a low-maintenance solution that requires minimal upkeep once installed.
Disadvantages of cavity tray
1. Additional Cost
These require additional costs that must be factored into the overall building budget. While the cost is relatively low, it can add up when used extensively throughout the building envelope.
2. Installation Complexity
It requires the skilled installation to ensure they are properly installed and sealed. If not installed correctly, they may not provide the intended protection against water ingress.
3. Maintenance
While these trays are generally low maintenance, they may require occasional cleaning to prevent blockages or damage to the drainage system.
4. Limited Effectiveness
These are only effective when used in conjunction with other building components, such as flashing and weep holes. Without proper integration, they may not provide sufficient protection against water ingress.
FAQ
What is a cavity tray?
A cavity tray is a component used in construction to prevent the ingress of water into a building through the cavity wall. It is typically made of a rigid material, such as plastic or metal, and is installed at the base of the cavity to channel water away from the building.
Where are cavity trays used?
These trays are used in buildings with cavity walls, which are constructed of two layers of masonry separated by a gap or cavity. They are typically installed at the base of the cavity wall above doors, windows, and other openings to prevent water ingress.
What are the benefits of using a cavity tray?
The main benefit of using these trays is to prevent water damage to a building. Without it, water can penetrate the cavity wall and cause dampness, rot, and structural damage.
What types of cavity trays are available?
There are several types of cavity trays available, including stepped, flat, and flexible.
