I have an old house with 7" standing timber plastered on the outside (about 20-30mm?). I am now going to build a balcony for access to a patio (two-story), where I will attach a 170x45 pressure-treated beam to the wall.
The thing is that in the near future, the house will also be replastered, so I'm debating the best way to attach this beam. Should it be attached on top of the plaster, or should I chip away the plaster and screw it on, to then plaster "around" the beam as a kind of weather protection? I was thinking of placing a waterproof membrane between the timber/plaster and the beam to prevent moisture migration.
Does anyone have any ideas on how one should think about this? The plaster seems to protect the underlying timber very well from the weather, but things will, of course, change if the wood is exposed outside of the plaster. If I weren't replastering, I would probably just attach it on top of the plaster and screw it into the timber, but I'm not sure if I will complicate the replastering significantly at this stage. Of course, the balcony can be stabilized and detached in the future during the replastering, but the movement margin will be somewhat limited by the poles holding the outer edge of the balcony in place.
Any input?
