GRP against TF wall with breather - over or under?

[BartW]

Hi,

silly question probably, but we are to do grp on the roof terrace and that butts up against the wall which has got a TF200 breather on it. It is a timber frame wall with OSB on it (and the said breather). 
 

would you:

- fold up the breather, install grp trim, install GRP against the wall and above, then fold back the breather and tape on the surface of the finished abutment

 

- or try to run a grp trim against the face of the breather, then GRP against it, and tape on top of it?

 

decisions decisions…

[markc]

Leave the breather as it is. The grip upstand is a solid barrier so the breather is doing nothing at that location

[BartW]

8 minutes ago, markc said:

Leave the breather as it is. The grip upstand is a solid barrier so the breather is doing nothing at that location

thanks, I am being paranoid about water possibly being driven behind the trim if an air pocket occurs or the joint fails in any way. 
 

my logics is that it is a neater joint against flat OSB sheet than the draped breather. 
 

 

[markc]

I can see where you are coming from, either way if ok so go with whatever makes you more comfortable or what the installer recommends

[SteamyTea]

How is the GRP trim going to be attached?

Mastics or mechanically?

[BartW]

4 hours ago, SteamyTea said:

How is the GRP trim going to be attached?

Mastics or mechanically?

Grp trim should be nailed to roof snd masticed to wall to maintain flexibility. Breather draped over it and grp onto is my preference here. 

[SteamyTea]

27 minutes ago, BartW said:

Grp trim should be nailed to roof snd masticed to wall to maintain flexibility. Breather draped over it and grp onto is my preference here. 

Sounds OK, but maybe carefully screw the GRP in place, after drilling clearence holes, it can split easily.

 

 

[BartW]

6 hours ago, SteamyTea said:

Sounds OK, but maybe carefully screw the GRP in place, after drilling clearence holes, it can split easily.

 

 

Screws are not good for this I am afraid, as they countersink into the trim and if not split it, tend to sit proud on the surface. 
 

Clout nails on the other hand are fully flat headed and go like butter