Type C Cavitray (Cavity Trays Ltd)

use
A range of preformed, ready-shaped DPC cavitrays for use with proprietary metal lintels. Also suitable for use with cast in-situ, pre-stressed and pre-cast concrete lintels.

introduction
The upgraded Type C cavitray range fulfils the latest British Standards and NHBC requirements which demand an independent DPC to be used with proprietary metal lintels in specified locations and applications. In addition, Type C cavitrays may be used to provide the obligatory DPC, when constructing using concrete lintels of most styles.

type C cavitray
The C cavitrays provide a harmonizing yet independent DPC tray to all lintel openings. Manufactured from solid DPC, Type C cavitrays are pre-shaped to suit customer's specific construction needs. Being pre-shaped means the installer establishes exactly what is being built into the cavity wall, whilst eliminating the dangers of distortion and misplacement.

Available in a choice of two materials, Type C cavitrays are not limited to one cavity width. Our design permits numerous cavity widths to be accommodated, whilst maintaining a clear cavity compartment area. This is important if the risk of mortar

build-up within the cavity is to be avoided. Available to order with each Type C cavitray are Type L lintel stopends. The Type L stopends have an integral anchoring butyl base which permits them to be applied in the most appropriate perp position towards the end of each Type C tray.

When stopends are applied, water is prevented from discharging into the cavity. Instead, water is directed and discharged out of the building fabric via weepvents which are incorporated within appropriate perp joints. Weepvents also permit the wall to breathe. On the following page some examples of profiles available are shown. All profiles may be supplied with the cavity upstand either returning into the inside skin or terminating against the face of the inside skin. If the tray is to return into the skin, this is easily accommodated within an appropriate bedding course. Alternatively, upstands can finish against the inside skin face. This is possible because they are rigid, self-supporting, and slightly tensioned take up the maximum cavity width. Unlike traditional DPC they do not require aid to prevent sagging. Select the preferred format, taking into consideration any regional requirements (see Building Regulations paragraph).

designers'
comments

Type C cavitrays are
manufactured from solid
DPC polypropylene. Solid
DPC means there is no
reliance upon surface
coatings for protection.
Protective measures for
steel lintels, including
provision of DPCs where
appropriate, should comply
with BS 5977:Part 2. This
stipulation is qualified
within BS 5628-3:2001
(5.11.6). Experience in
manufacturing Type
cavitrays has highlighted
four principal
considerations:-

1) The need for a material
to be sufficiently strong
enough to resist accidental
damage during
construction yet sufficiently
durable bearing in mind
the planned life of the
building.

2) A material that should be
resistant to stress/creep
deformation, and thus able
to withstand the load to be
imposed upon it. (Creep
deformation is dependent
upon the stress
(compressive) induced by
the structure weight bearing
upon same.)
The stress is normally
graded into four classes:-
a) High is above 2.45N/mm
which is generated in walls
higher than 10 storeys.
b) Medium in the 0.5M/mm
to 2.5N/mm range (4-10
storeys high.)
c) Low in the 0.1N/mm
range generated in walls.

Type C DPC cavitrays are strong, lightweight and virtually puncture-proof. They eliminate all wastage. They also eliminate the damage element normally associated with the site-formed felt or polymer DPCs. Of particular interest to the house builder/developer, the use of Type C cavitrays provides an excellent way of controlling cost, quality and workmanship on site, whilst satisfying the latest NHBC and British Standard regulations. Trays can be packaged per dwelling, for easy identification and storage.

The European Standard for lintels: BS EN 845.2:2001 qualifies corrosion protection required in any individual application, making reference to "the degree of exposure and climatic conditions". We recommend the use of an accompanying Type C cavitray at all times to comply with the new European Standard, which is not specific as to where or when such exposure conditions apply.

Specifying of Type C cavitrays at all times to ensure compliance is accordingly recommended.

sizes
Profiles available to suit Birtley, Catnic, Dorman Long, Harvey, I.G., Jones, Naylor and other popular lintels. Also available in non-standard profiles to suit customer's requirements. A Type C cavitray schedule can be prepared to harmonize with any lintel schedule, thus ensuring compatibility and eliminating wastage which might otherwise occur. Single maximum length 2.4 metres. Silicon bond/glove-lap to make up longer lengths. Base material thickness of 1.5mm.

material
Solid polypropylene or solid austenitic stainless steel. Securtex finish on polypropylene.

colour
Black or self-coloured stainless steel.