Waterproofing gable end single brick wall on 8th floor

We live in an apartment on the top (8th) floor of a heritage-listed 1930s brick-built building.
The pitched roof above has been retiled in the last 5 years and the sarking replaced so the roof is now sealed.
However, despite receiving external treatment from abseilers, the single brick wall above the North-facing gable ends is saturated (tested with moisture meter) and water is running down inside the wall from the masonry and onto the ceiling of our apartment below. This has been especially bad after rain storms combined with strong NE winds.
Is there a product that can be applied to the inside of the wall to prevent water penetration?
Alternatively is there a product that can be applied externally (by abseilers) without altering the appearance of the building?
There is a damp course at the foot of wall but it is cut off flush to the wall on the inside so it doesn’t prevent water getting into the ceiling below.
It has also occurred to me that instead of trying to stop water coming through the wall, it may be easier to tank the area above the ceiling to collect the water in an internal gutter and connect the gutter to a downpipe. Is there a recommended product for this?
I’m on the Strata committee and want to ensure that we get the right treatment this time as previous attempts haven’t worked.

 

I was thinking chemical dampcourse treatment of the entire wall......

https://www.google.com/url?sa=t&sou...wqsBegQIHxAB&usg=AOvVaw2JBJojNsSdcbTSPnhDQlZO

 

You need to limit the water getting into the wall - eg overhang on the fascia/eaves. Membranes applied to the inside face of the wall fail as moisture builds up behind them and pushes them off the wall.

Although I am a fan of this type of product, it won't work in this application.

It requires a more considered approach.

The single brick wall is a wet wall by design, in a cavity wall, the moisture runs down the inside face and through the external brick down to the flashing and is directed out of the wall through the weepholes at each level. Water doesn't reach the inside skin unless the cavity is breached.

Step 1 - I would suggest that a new Alcor flashing and weep holes be installed with a 2-3 brick step up to the internal course or a rigid aluminium flashing with appropriate bends to direct the moisture out of the building. The work will involve the bricky cutting out 4-6 bricks at a time, inserting the flashing, relaying the bricks, then moving to the next stage 1m away and coming back for the adjoining sections.

Without seeing the details of the dampcourse at ceiling level, are the weepholes blocked? There's also a lack of turnup or capacity to hold water if that's a flashing intended to direct water out of the building.

Step 2 - Silicone treatment to the external face of the gable to limit water penetration. This needs retreatment every few years.



Although the details above are for inter-floor flashing, the same principles apply to the gable and roof space. The flashing must be continuous through the wall and away from the inside face.

 

I've done the chemical dampcourse for a terrace wall previously due to moisture, because the bricks were porous, the chemical dampcourse made them moisture resistant, not sure how long it lasted but we got a few years out of it