damp wall on alkali primer sealer

[stbeaver1]

I have prepd a wall on which I want to hang wallpaper with an alkali primer sealer. It's an external corner of an end terrace which I assumed was attracting condensation as it was sweating a bit but just in case it was water coming in from outside following all the wet and cold weather we have had I primed it to seal any water ingress out.

Having applied the sealer I allowed it to dry and painted over it with a normal emulsion before wallpapering. A couple of days later the wallpaper started to peel off and I discovered that the wall is damp behind the wallpaper, mostly exactly where the primer sealer was applied.

Is this just a condensation problem?

If so is it normal to see more condensation on the sealed area of the wall given that in effect I've painted on a water resistant barrier?

And if so again, what's the solution so that I can hang wallpaper without it soaking up water and peeling? Any suggestions welcome!

Is it going to be as simple as improving air flow etc.?

Any suggestions for solutions or is dry-lining and / or putting in an air brick in that corner the right course of action?

 

[dcdec]

Alkali resisting primer is to protect walls against alkali attack prior to solvent based coatings as far as i know its not designed as a damp sealer. You really need to find the source of the water penetration, could be pointing, crack in the brickwork or problem with the gutters and many other things. Zinsser do a product think its called water tite that would be more suitable, but don't really believe in using paint to solve damp problems.