Cavity Trays Explained: Types, Uses, and Choosing the Right Solution for Your Build
Nov 21, 2025
Cavity trays are a small but essential part of modern masonry construction as they protect buildings from moisture penetration. Installed within the cavity of external walls, they reroute water and channel it back outside through weep holes. Without cavity trays, buildings can suffer from damp and structural issues.
In this article, we explain what cavity trays are, discuss the main types available, including E, G, X, and C, and help you choose the right option for your build.
What is a cavity tray?
A cavity tray is a damp-proofing component placed above junctions, such as roof abutments, window openings, and horizontal interruptions in the masonry. Its job is to prevent moisture that enters the outer leaf of a cavity wall from affecting the inner leaf. The tray slopes outward and features stop ends and weep holes which ensure water is collected and removed before it causes damage.
Cavity trays are usually made from polyethylene, polypropylene, lead, or flexible polymeric membranes. Pre-formed trays are often preferable as they reduce installation errors and ensure compliance with building regulations.
When to use a cavity tray
Cavity trays should be used in several places, including:
- Roof abutments
- Openings e.g. windows, doors, and vents
- Changes in cavity level, such as over lintels or at stepped foundations
- Horizontal wall penetrations
Types of cavity trays
There are numerous types of cavity trays available, including types E, G, X, and C.
Type E cavity tray
Type E cavity trays (or refurb trays) are versatile and typically used above window and door openings or in areas that need a standard horizontal damp-proofing solution. They’re simple to install and can be adjusted to suit different cavity sizes. Type E trays are used for inserting into existing walls and are a great choice for remedial applications.
Common uses
- Over external door and window lintels
- At continuous horizontal cavity interruptions
- In brickwork with consistent coursing
Advantages
- Easy and quick to install
- Cost-effective
- Suitable for most standard cavity wall designs
Type E cavity trays are often the best option for straightforward installations that don’t involve complex junctions or changes in cavity level.
Type G cavity tray
Type G cavity trays are designed for new builds and water is evacuated via a weep vent. They’re ideal when working with changes of level and horizontal intersections in new buildings. Type G cavity trays can be supplied with optional lead flashings which create a durable, waterproof barrier.
Common uses
- Changes in wall level
- Where a roof meets a wall e.g. garage or porch
- At bay windows and other horizontal features
Advantages
- Adjoining lengths interlock and the tray is self-supporting
- Manages building movement
- Compatible with different construction types
If your new build has a sloping roof-to-wall intersection, a Type G cavity tray is the best option.
Type X cavity tray
A Type X cavity tray prevents water from penetrating a cavity where a pitched roof meets the wall. It creates a stepped, continuous barrier that guides water from the external leaf away from the structure, preventing damp from reaching the internal wall.
Common uses
- Gable abutments
- New extensions with sloping roofs
- Remedial work
Advantages
- Adaptability
- Non-disruptive installation
- Continuous stepped protection
Type C cavity tray
Type C trays are specialist cavity trays used around vertical elements that interrupt the cavity. They provide a sealed, waterproof barrier around penetrations that cannot be protected by standard horizontal trays. They’re ideal for use in timber frames and cavity lintels.
Common uses
- Soil vent pipes
- Flues and service penetrations
- Structural steelwork passing through external walls
Advantages
- Ideal for awkward or non-standard junctions
- Prevents moisture tracking around services
- Helps maintain thermal performance
Type C is the right option when you need to maintain cavity integrity around penetrations.
Choosing the right cavity tray
Selecting the right cavity tray requires an understanding of the junction you’re working on. Here are four top tips:
- Match the tray to the junction type
- Horizontal openings – Type E
- New builds – Type G
- Sloping abutments – Type X
- Vertical penetrations – Type C
- Consider weather exposure
Locations with heavy wind-driven rain require robust solutions.
- Use pre-formed trays where possible
They reduce installation errors and ensure proper drainage slopes and stop ends.
- Follow manufacturer guidelines
Each manufacturer may offer different dimensions or have different requirements.
Cavity trays play an important role in protecting buildings from moisture-related damage, and understanding the differences between types E, G, X, and C helps ensure each junction is properly protected and compliant with building regulations.
At strukta, we sell a range of cavity trays to suit your construction project, whether you’re working on a new build or carrying out remedial work. View or request our catalogue today and order the cavity trays that best suit your requirements.