Foundation Detail and Waterproofing

[GEO-PAR]

Hi All,

 

Reposting this as I originally put it under 'General Construction Issues' and haven't received any comments.   

 

I'm just looking for a sanity check on my foundation detail (to hopefully provide some peace of mind before I keep building up).

 

I'm constructing a highly insulated new build (200mm PIR above DPC, full fill XPS below DPC).  My foundation detail is based on a Greenbuilding Store case study: https://greenbuildingstore.co.uk/golcar-passivhaus-ground-floor-foundations/

 

I originally designed it as per below, where the Surecav meets the DPC: Full fill XPS below cavity tray.  Then the offcut pieces of the XPS are used above the tray below the first wall tie. Kingspan PIR is then used above the first wall tie up to eaves. 

 

The problem occurred when attempting to add the XPS back in above the DPC (to fill what would otherwise be a triangle cut out).  The thickness of the DPC caused the XPS to get kicked out compared to the PIR above.  This meant that there would have been a step in the SureCav.  To get over this, I introduced a second cavity tray that lapped up the face of the bottom board of PIR and effectively did a solid fill cavity below where the stonework just got built up to the back of the XPS. 

 

 

 

Does anyone foresee any issues?  My worry in hindsight (after building up past this to about 4ft, is that the cavity tray I inserted only laps up the face of the insulation.  Any water ingress behind the insulation has nowhere to go.  Am I over thinking this and it will be fine, or do people think I may have issues in the future?