DPC Detail - New Extension To Solid Wall

Discussion in 'Builders' Talk' started by AnotherDIYer, Jun 12, 2019.

  1. AnotherDIYer

    AnotherDIYer New Member

    Hi all,

    I'm undertaking a fairly ambitious project (For me, anyway) and DIY building an extension. When the first BCO came around we had a chat and he told me "not to worry" about vertical DPC's. At the time I thought that was an easy win, but now I'm about to start laying I'm getting a bit nervous/paranoid.

    Situation is:

    Existing House: Solid brick, double skin wall. Standard slate DPC, then a normal course of bricks, then another course with injected damp proofing. We fully renovated the house several years ago and have had no issues with damp.

    New extension: Conventional cavity wall, tied in using wall starters. FFL is between the slate and injected dpc:

    https://imgur.com/1cNer8K

    (Ignore the ground level being too high there, it'll get sorted)

    So my new DPC is going to be in the same place as the FFL - what do I need to do to ensure there's no DPC bridging here? Am I worrying over nothing?
     
  2. Joe the Plumber

    Joe the Plumber Active Member

    As the "injected DPC" is snake oil flogged by cowboys from covered wagons and won't actually be doing anything, I'd ignore it and just make sure you aren't breaching the slate one that does actually do something. But the ground shouldn't have lots of water sitting in it in any case. If it has, there's a problem with a leak (or other water source) somewhere.

    With any damp problem, locate and resolve the source of the water and the damp will magically go away. Yours (I'm guessing here of course) might well have been caused by rain water trapped behind that stucco.
     
  3. AnotherDIYer

    AnotherDIYer New Member

    Agreed! So what's the best way to ensure I don't bridge the slate DPC when I'm building my new wall against it?
     
  4. Joe the Plumber

    Joe the Plumber Active Member

    I'd suggest cutting the edge of your wall's new damp proof membrane into the slate course.
     

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