Cavity Trays Ltd

Type K Circular
Cavitray

DPC cavitray for circular
bullseye windows

in brief...

  • Horizontal and vertical DPC in one unit
  • Enveloped 360 degree protection
  • Permits continuity of cavity insulation
  • Frame position options
  • Range of sizes

 

   
   designers'
   comments
    
    GBG33 published by the 
    BRE in September 1999 
    draws attention to the
    importance of DPCs 
    around openings.  It 
    qualifies how water
    must be prevented from 
    reaching the inside skin, 
    and the manner in which 
    vertical DPCs must be 
    lapped to prevent water
    ingress.  Circular 
    openings require
    particular attention.  By
    combining vertical and
    horizontal protection on
    one moulding unit, the
    Type K addresses all
    objectives.  
    Thus the common areas 
    of weakness are 
    eliminated.

 

use
Cavitray damp-course for circular openings.

introduction
Whenever a circular bullseye window is installed, the builder faces the difficult task of providing correct DPC protection.  A conventional horizontal damp-course leaves vulnerable areas which readily accept and transmit dampness.  Ideally, the damp-course should follow the shape of the circular window and provide 360° protection.  This is achieved with the circular Type K cavitray.


type K cavitray
The Type K cavitray is manufactured from solid DPC and



 is supplied in one piece ready to receive the circular window.  It fits snugly around the window frame, providing a 360° barrier.  The circular window is immediately enveloped in a durable cavitray thus ensuring correct and thorough protection.  The inside skin of the cavity wall and the sides of the circular window frame are protected from dampness.

The unique design of the Type K cavitray accommodates numerous cavity widths and numerous frame positions.  The cavitray travels vertically downwards within the cavity, until it passes the bottom of the circular window.  At this point the base projects forward so any arrested water is directed away from the inside skin.  Type W weepvents may be incorporated to aid cavity wall ventilation if appropriate.

thermal zoning
(optional)
Positioning of a circular window mid-cavity is one of the most economical methods of build and permits the introduction of a circular polystyrene thermal collar.  Thus a thermal zone is introduced to the perimeter of the entire frame.  The collar is manufactured in dimensionally stable polystyrene, with a low thermal conductivity figure 

of between 0.026 and 0.028W/mK.  Specify Type K plus thermal collar to fulfill both DPC cavitray and thermal zoning requirements.

sizes
Available to suit most popular circular window sizes.
Sizes supplied include
470mm, 600mm, 630mm, 675mm, 700mm, 750mm, 800mm.
Perimeter gussets allow a degree of frame size tolerance.  Special sizes and other sizes available.

material
Thermo-stable polypropylene DPC type 6, heavy-duty.

colour
Black.

installation/site work
Introduce window frame into protective sleeve of cavitray.  The Type K should be built- 

 

  

in at the appropriate stage in construction, following the recommendations of BS5628.  Ensure Type K takes up correct shape with cavity and is returned into the inside skin as per instructions.

bill of quantity
wording
Type L cavitray for circular openings manufactured in type 6 heavy-duty DPC from Cavity Trays of Yeovil, Somerset BA22 8HU (01935 474769).
Incorporate Type K cavitray DPC following manufacturer's instructions.
Specify number and size of each Type K cavitray  required.  Request liability/conformity document upon completion.

building regulations
Building Regulations, British Standards and NHBC requirements  may be satisfied with use of this product.  See page listing references.

ordering
See inside back cover for immediate service throughout the United Kingdom.  Merchant distribution network.

related products and applications
See Type BA which provides DPC for curved head openings.  For DPC plus arch former, see Type A and Type AA.  For perp ventilation see Type W.

   
   designers'
   comments
   360° total protection.  Suits
    numerous cavity widths.
    Accepts forward or mid-
    frame positions.  Isolate 
    frame edge from direct 
    masonry contact.  Cavity
    insulation may continue 
    across front of cavitray.
    Branded with name and 
    logo as proof of type and
    accompanying warranty.

 

 

Cavity Trays     phone 01935 474769 fax 01935 428223 email enquiries@cavitytrays.co.uk