Sealing cotogram for applying flashing tape

The edge of my porch to wall has water running down it when it rains heavily.


It’s sealed presently with Soudaseal 240FC, but I’m guessing that it hasn’t got into the fine gaps of the cotogram.

I plan to run some kind of paint/sealer along the edge above the Soudaseal to flood the cotogram gaps and then apply a flashing tape onto that and over the top of the sealant.

Any suggestions on paint/sealer to use to get into the cotogram ?