DPM detail

[Oz07]

What are the pros/cons of this alternative DPM detail.

I thought as a positive it would keep the internal cavity perimeter blocks dry below DPC. A 'con' is any settlement in the sublease and DPM would be likely to tear. Would this not happen with the usual method though also?

[Brickie]

From a purely practical viewpoint-it means you have Dpm laid out across your site whilst your building what’s shown. The level of  care needed to prevent it being punctured would be substantial. 

If keeping that inner skin dry is a motivation,you could conceivably just do a ‘wraparound’ detail,& then lap the Dpm into the brickwork in the traditional way. 

[Oz07]

Yeh I thought that although would probably be laid from outside overhand the blues for this one block plus one brick course. Then insu and slab. Like you say probably be easier just to lay on a wide dpc and wrap around. 

No benefit really was just throwing the idea out there

[Oz07]

I've now got opportunity to do this as drawn above. Rather than take the DPM up the outside of the block though I would probably just cut it an inch or so into the cavity then fold down. Wouldn't get damaged on site as these blocks be laid from the outside. Remembering I have a secondary DPM ontop of insulation I can't see what I have to lose apart from making the first layer easier! Any more thoughts?

@Brickie? @PeterW? @Declan52

[Declan52]

Under the inside skin of blocks you build a normal dpc in. You can use  18" which will give you enough of an overlap to slide your dpm under and glue/tape so you get a continuous barrier. Once the first course is on and hardened you put sand over the top to cover the dpc so any droppings from the blocks hit the sand. When the blocks are all done the droppings will come off the dpc easily and your left with a nice clean dpc with no puncture holes. 

The inside of the cavity will dry out so don't be worrying about that .

You can tank the cavity to stop water getting through instead of doing that wrap bit in your first pic. On the pic I should have continued the red line to the left so it's built in the wall with the blocks holding it in place.