cavity tray at DPC level ?

[sm_jamieson]

I have recently seen on a bricklaying tutorial, the mention of a requirement for a cavity tray at DPC level, along with weep vents at regular intervals above the DPC. I've never noticed this in the regs before, and assumed the cavity extending a distance below the DPC would be enough for water running down to soak away. The tutorial used an extra-wide DPC in the outer leaf and curled it upwards. It looked like it was tucked into the inner leaf higher up. I have seen this before, but never at DPC level. Can someone confirm if I need a cavity tray at DPC or not ? Thanks, Simon.

[sm_jamieson]

Just noticed this is an option mentioned in part C. The example shows a cavity extending downwards. Still not quite sure why you would choose to do it that way though. Simon.

[Rob]

I'm doing a parapet wall cavity at the moment: see

think this may answer your question Rob

[Hugo Nebula]

There may be situations where the walls need to be solid up to ground level, therefore the option of leaving the 225mm clear below DPC isn't possible. It's a bit similar to the sitution I had today, where the ground level was the same or slightly higher than the proposed floor level, so I suggested a similar arrangement to this diagram with a DPC linked to the oversite membrane continuing behind the inner leaf.

[Rick Hughes]

On all builds I have done there is a cavity descending below DPC ... normally you would want any water to drop down there.

However on my current place I have a plinth stretcher course 750mm up the outer wall, as the wall above this is effectively stepped 65mm back at that point, I did insert a sheet DPC at this level, as you mention .... outer edge was at the top of plinth stretcher course, this was folded upwards and across to inner skin ... so any water coming down cavity or inner face of outer skin is caught on this tray, and then escapes via weep holes (or in fact proper vents I installed) I did this as there was a change in wall thickness and there was a rick of water coming down inner skin could bounce off the point where it stepped and hit inner skin.

Below plinth there is normal DPC at 150mm above GL, and that is as usual, i.e. cavity open so any water would go down there.