Are cavity trays required?

Cavity trays are an important feature in external cavity walls to assist in ensuring any water is directed outside the building. Incorrect specification or installation can lead to defects in the wall and water damage that might be expensive or needlessly destructive to rectify.

Is a cavity tray required at DPC level?

There isnt normally a cavity tray at dpc level, unless in instances where the likes of a Radon Barrier is required, which should overlap inner wall, cavity and outer wall. You would then need a cavity tray above with weep holes.

Where should cavity trays be installed?

Cavity tray best practice

  1. Cavity trays should be installed over all external door and window openings including bay windows and at roof abutments, both horizontal and pitched.
  2. The cavity tray should be correctly located directly over the window/door head.

Do cavity trays need to be non combustible?

Conditional that both skins of the cavity wall are of masonry in the form of either brickwork, blockwork or concrete, cavity trays may be used in their usual form. Where both skins of a relevant building’ fall outside of this qualification, non-combustible trays must be used.

Are cavity trays a building regulations?

For this reason, building regulations require cavity trays to prevent water penetration where the cavity of an external wall is bridged or where an external wall becomes an internal wall at a lower level. Cavity trays are designed to ensure that water is diverted to the outer leaf or clear of the bridge.

Do you need a cavity tray with full fill insulation?

Full fill cavity insulation generally leaves no space for the cavity trays to be fitted. The insulation must be cut in order to allow the cavity trays to be fitted to form a localised clear cavity of no less than 50mm.

How many cavity trays do I need?

To calculate quantities, allow one cavity tray per course on each roof slope. One stopend starter or corner starter is needed per roof slope, and one ridge tray at each apex.

How high should a cavity tray be?

The cavity tray should fully protect the opening. A cavity tray should be provided 150mm above any adjoining roof or balcony surface. The tray should be lapped over any roof upstand or flashing to ensure water penetrating into the cavity does not enter the enclosed area.

Can you retrofit cavity trays?

Type E cavity trays are beneficial for retrofitting projects as they only require one course of bricks to be removed, which saves time, disturbance of the building structure, and costs.

Do all houses have cavity trays?

It is only since the 1920s that external masonry walls in the UK have widely adopted a cavity construction. Before this, they were generally a solid construction. Cavity trays are included in cavity wall constructions where there are penetrations across the cavity, such as: At an abutment with a roof.

What is a DPC cavity tray?

What is a cavity tray? A cavity tray is essentially a damp-proof course (DPC) that crosses the cavity of a cavity wall in order to prevent dampness from permeating the internal skin of a wall. Cavity trays are a unique range of single-element systems that are available off-the-shelf.