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UK Cavity Tray Types & Specifications
Cavity tray DPC types, widths, weep hole spacing and installation requirements for UK cavity wall construction.
Cavity Tray Types
| Type | Application | Material | Notes |
|---|---|---|---|
| Horizontal tray | Above lintels, base of cavity | Polypropylene / lead composite | Must span full cavity width + both leaves |
| Stepped tray | Roof abutments (pitched roof to wall) | Pre-formed polypropylene | 75 mm steps to match brick coursing |
| Catchment tray | Below openings (sills) | Polypropylene | Collects water running down cavity |
| Caverntray | Ridge abutments, parapet walls | Pre-formed rigid plastic | For complex junction details |
| Perpend weep vent | Weep holes in outer leaf | Plastic insert | Max 450 mm centres along tray |
Tray Width Requirements
| Cavity Width (mm) | Min. Tray Width (mm) | Notes |
|---|---|---|
| 50 | ~300 | Must extend min. 100 mm into each leaf |
| 75 | ~325 | Standard domestic cavity |
| 100 | ~350 | Wide cavity with full-fill insulation |
| 150 | ~400 | Wide cavity with thick insulation |
Key Installation Rules
- Cavity trays must slope toward the outer leaf at a minimum fall of 1:12
- Stop ends must be fitted at each end of the tray to prevent water running off the sides
- Weep holes at maximum 450 mm centres (every other perpend in stretcher bond)
- Trays must project 5 mm beyond outer face or use weep vents
- Minimum 150 mm upstand on the inner leaf side
- Laps between tray sections: minimum 100 mm, sealed with compatible adhesive
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See the DPC Specifications for damp proof course types, or the UK Lintel Sizes for lintel specifications above openings.
Frequently Asked Questions
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Last updated: April 2026
Verified against UK standards 路 estimates only, confirm with your supplier.