cavity tray

[goldmember81]

I'm buliding an extension to the kitchen using a cavity wall construction and am wondering if i need to put a cavity tray at damp coarse level?

[buildersmate]

Cavity trays are designed to stop any water that has made it through to the inside of the outer brick skin running down. They are used where you put a single storey extension against a higher two storey wall, at the point where the lintel goes in (enabling access into the extension). They stop any water flowing through, and direct it back outside (onto the roof of the extension). You do not need a cavity tray at DPC level - you need to run a roll of DPC material across both brick courses at this level. If you are doing the job correctly you must have Building Regs approval for this job and the Building Control Officer will probably want to check this aspect.