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Leaded Inter-loc Horizontal Cavity Trays for New Build

Leaded preformed horizontal cavity tray system, including corner and stop end units, suitable for new build brick, block and stonework constructions.

Featuring integral interlocking lapped joints to securely join cavity tray lengths together and create a watertight run which eliminates the requirement of additional tray jointing adhesives (taping etc) on site.

Supplied with factory fitted lead flashing (long or short lengths), which presents a quicker and straightforward installation, as the cavity trays and flashings are installed in a single operation, rather than multiple trades, as well as a consistent protective and aesthetical finish.

For external wall constructions not exceeding 102.5mm in thickness and clear cavity widths of between 50mm and 125mm

  • trays to suit clear cavity widths of 126mm+ are available to order.

Available in two standard lengths, to allow build to standard brick bonding lengths for ease of use:

  • 4 standard brick length (900mm) for general use
  • 2 standard brick length (450mm) for making up a run to the required length.

Preformed horizontal cavity trays provide protection from water penetrating the external wall leaf of a cavity wall down through to the internal wall leaf in specific vulnerable areas across the building such as:

  • the abutment of a flat, lean to or mono-pitched roof
  • over concrete ring beams
  • over building components that can act as a through cavity carrier such as air bricks, meter boxes, ducts and cavity liners.

Also available unleaded and supplied with mortar barrier strips (to aid the installation of post fitted lead flashing).

Preformed cavity tray systems are an effective method of DPC and present many benefits including reliability, speed of installation, reduced cold bridging opportunity and site waste.

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Features & Benefits

  • Tough and stable DPC method
  • Can save time, labour and material wastage
  • Consistent aesthetic and protective finish
  • Suitable for brick, block and stonework constructions
  • To fit clear cavity widths of between 50-125mm
  • Can be time, labour and material saving
  • Cold bridging opportunities reduced
  • Generally doesn’t require cutting into insulation
  • 150mm high back upstand exceeds NHBC requirements
  • Interlocking tray joining system eliminates additional joining adhesives 
  • Allows inner and outer wall leafs to be built independently if required
  • Doesn’t degrade over time or under high loads
  • Isn’t affected by temperatures
  • Rigid construction that won’t collapse into cavity
  • Can be dispatched in convenient plot/area specific order consignments upon request


External cavity walls abutting flat, lean to or mono pitched roofs such as:

  • attached outbuildings and garages
  • conservatory and extensions
  • porches and bay windows
  • attached buildings with different roof lines.

Over concrete ring beams or slabs and building components that can act as through cavity water carriers such as:

  • air bricks and cavity sleeves
  • ducts
  • meter boxes.

For external cavity walls built from standard brick, block and stonework:

  • not exceeding 102.5mm thickness
  • with clear cavity widths of between 50-125mm
  • non- standard requirements are available to order, please contact us with your project details.

Technical Information

With pre-formed cavity trays it’s not strictly necessary for the tray to span all the way across the cavity (except projects in severe weather exposure areas).

As long as the cavity tray stands back from the rear face of the masonry and projects back into the cavity far enough to intercept drips falling from the wall ties, then it will perform effectively.

If installing cavity trays with a partial fill cavity insulation, please deduct the insulation material depth to calculate the available ‘clear cavity width’.

Cavity trays work in conjunction with weep holes:

  • trays collect and retain water inside the cavity wall
  • weep holes discharge water back out through the external cavity wall leaf.

Weep holes must be provided in every horizontal cavity tray to comply with Building Regulation requirements. 

We recommend that purpose made weep holes/weep vents are installed, such as Timloc’s:

  • wall weep vents – 1143 range
  • concealed wall weeps – TW1 range.

Stopends must be specified and installed if a cavity tray has to be cut down to suit the project.

How to Order

We strongly recommend that customers take advantage of our free of charge cavity tray specification and project take off service.

Our Technical Services Team will be pleased to advise the most suitable products for your project and will prepare a fully itemised schedule of quantities if required.

To calculate horizontal tray quantities for standard brick/block length constructions:

  • divide the overall length of the cavity tray run by .225 (representing one standard brick and mortar joint) to give the number of trays required
  • divide the number of trays required by 2 for (IL2 2 brick tray) or 4 (IL4 4 brick tray)
  • always round up to the next tray - excess length has to be cut down
  • always use stopends if the cavity tray has to be cut down
  • stopends will not be required when the cavity tray run is built within the body of the building i.e. bay windows.
  • for these applications the tray’s integrated stopend can be built into the next available joint projecting past the abutting roof

Please provide the following project information with cavity tray enquiries:

  • type of roof construction (pitched, mono, flat)
  • length of abutting roof
  • external wall material and thickness
  • clear cavity width
  • cavity insulation material and thickness
  • are unleaded, unleaded or unleaded with mortar barrier strip trays required?
  • are long or short lead lengths required?

Installation Advice

On-site installation and best practice guidance is all part of our service, please don’t hesitate to contact us to arrange a site visit.

Please don’t hesitate to contact the Timloc Technical Team if there is any doubt regarding installation.

When specifying and installing horizontal cavity trays it is important to consider the following recommendations:

  • allow for the cavity tray run to be slightly longer than the overall width of the roof abutment or area requiring tray protection (a minimum projection of 150mm is recommended)
  • we recommend that horizontal trays installed to protect a roof abutment should be 150mm above the finished roof line - no less than 75mm
  • the exposed area between the base of the cavity tray and the roof covering must be protected by an appropriate flashing
  • cavity trays must always be bedded onto fresh mortar - never dry bedded
  • the masonry laid over the cavity trays must also be bedded onto fresh mortar - approximately half way through the mortar joint
  • the cavity area must be kept clean and free from mortar droppings and debris
  • a stopend must always be fitted at the start and finish of a run of cavity trays
  • Inter-loc trays feature integrated stopends, however a separate stopend must be installed if the last tray in the run has to be cut down to suit the project
  • separate stopends are installed using pre-applied butyl mastic seal
  • ensure that the release paper is completely removed from the stopend and that the application area is clean and dry
  • pressure must be applied along the full length of the joint area once the stopend and cavity tray are brought together
  • it is usually necessary to link a number of cavity tray sections together to form a continuous run
  • Inter-loc cavity trays feature an integrated capping system for joining units
  • if there is any doubt about the integrity of any joint DO NOT proceed until the joint is made good – apply additional suitable sealant if necessary
  • weep holes must be provided in the face of the wall along the cavity tray run to discharge any water collected within the tray system
  • we recommend that weep holes are formed using Timloc’s preformed wall weep vents (1143 range) or concealed tunnel weeps (TW1 range)
  • weep holes should be spaced every 900mm along the run (450mm over lintels) – ensure that 1 weep hole is provided per every Inter-loc tray in the run
  • if necessary for the cavity tray run to turn a corner – always use a purpose made unit (external and internal corner units available).  Never try to site fabricate this critical detail
  • high quality workmanship, cleanliness and attention to detail are essential with all cavity tray installations

Quality, Regulations and Standards

  • Satisfies all NHBC requirements
  • Manufactured to BS EN ISO 9001 quality management system
  • Manufactured to BS EN ISO 14001 environmental management system
  • Complies with all relevant Building Regulations
  • Meets all relevant British Standards
  • Flashings are Code Blue (milled lead as standard) as defined by BS EN 12588:1999

Material and Colour Choice

  • Horizontal Inter-loc cavity trays are injection moulded in 2mm polypropylene
  • Accessory products are vacuum formed in 2mm thick medium density polyethylene
  • Trays available in black only
  • Flashings are Code Blue milled lead as standard (formally known as Code 4)
  • Heavier codes of lead are available for:
  •   - areas of severe weather exposure
  •   - flashings that are to be fixed and sealed where they overlap

Lead Flashing Lengths

All leaded cavity trays are available with a choice of long or short lead lengths.  It is important to specify which is preferred. 

The general rules are:

  • short lead lengths are used for dressing over upstands of secret gutters and lead valleys  
  • long lead lengths are used for dressing over profiled tiles.
  • nbs plus
  • riba

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