How to lap DPC - up or down - complex junction

[Bigdeadbadger]

Was looking to borrow the collective experience of the forum on how to manage my DPC lapping.

 

buildup is 

SIPS kit (so Osb outer)

protec tf200

 

dpc 

sitting on insulated concrete slab 

with custom/extra upstand to insulate the soleplate.

 

My dilemma is

 

1) whether to lap the DPC up the osb, behind the tf200?

 

2) or lap it down into the channel for the slab upstand.

 

option 1 seems to have drawback of making a dpc bath for the sole plate leaving water no where to go.

 

option 2 pushes the water into this Chanel also with no where to go.

 

i can’t easily breach the outside layer of the insulated slab (with weep holes etc) as I also have a gas membrane which laps up the side of the slab insulation and upstand. Noting the gas membrane doesn’t need to attach to the house. I have BC sign off that it can stop at the top of the upstand. 

 

More pics in next post

[Bigdeadbadger]

[Mr Punter]

A drawing would make more sense here.  The breather paper for the SIP needs to direct any moisture away from the structure.

[Bigdeadbadger]

1 hour ago, Mr Punter said:

A drawing would make more sense here.  The breather paper for the SIP needs to direct any moisture away from the structure.

Here you go.  It's not the paper I'm that worried about.  That can easily lap down the wall and over the top of the EPS upstand (and another layer lapped under that one and behind the EPS upstand if needed) which will direct all water out from above.

Due to the upstand there is no classic cavity or way out for water that’s at the DPC level

 

Edited February 16 by Bigdeadbadger

[Russell griffiths]

Only having a brief look but is your drawing scale way out. 
according to the drawing, the eps upstand and bit that pushes in is wider than the sips. 
however in your pictures the eps bit that inserts looks to be  50-75mm wide. 
 

im really not happy with that eps standing above the sips kit without it being fully waterproofed, any water getting through the aluminium flashing will be trapped against the sips kit. 
 

 

[Bigdeadbadger]

28 minutes ago, Russell griffiths said:

Only having a brief look but is your drawing scale way out. 
according to the drawing, the eps upstand and bit that pushes in is wider than the sips. 
however in your pictures the eps bit that inserts looks to be  50-75mm wide. 
 

im really not happy with that eps standing above the sips kit without it being fully waterproofed, any water getting through the aluminium flashing will be trapped against the sips kit. 
 

 

 

Edited February 16 by Bigdeadbadger

[Bigdeadbadger]

Here is the "professional" version of the above (prior to gas membrane changes) , which is to scale, which is advocating for lap up approach.  

 

The EPS upstand is 150mm wide.  The SIPS panel 217mm.

 

I'm not keen on this lap up as any condensation has no way out, never mind water from rain.

 

Hence the ask for collective wisdom. 

Edited February 16 by Bigdeadbadger