Me again... Abutment detail on a TF house with open rain screen cladding

[BartW]

Hi,

I suppose I could not have made it any more difficult that it is...

 

We are to build a flat roof terrace on the top floor, and we have a junction of a GRP roof to timber frame wall. 

 

The said wall will receive battens, counter battens and vertical charred timber planks to the face.

 

The wall is currently Timber frame panel with OSB.

 

Key considerations:

- if it were to be a standard brick wall, I would use abutment trim and simulated flashing. Job done

- but here there is none of that.

- I considered running the abutment trim against the TF wall and OSB. I concluded that far in another thread. However...

- the said external wall is externally wrapped in TF200 breather.

- There will be an aluminium coping on top of it, but before

- I plan on running the VCL up the said wall to meet the top of it to create a continuous barrier

- nevertheless, this means I will be GRPing against a membrane again.

- I fear that if I do not lap the VCL to the top, I would be getting rid of a useful "tanking"

 

Or should I:

- run VCL and terminate below the abutment trim

- install abutment and seal the top of it with GRP

- install breather as planned, and extend to the top / underside of the coping

- proceed to installing battens, counter, vertical cladding

 

Am I overthinking this???

 

 

Picture below to show what I am mumbling about.

 

 

 

 

 

Thanks!

 

Bart