Though not urgent, your problem is a sign that bad things are going on. From your description, I’m confident that water is to blame. The real question is the source…
- Seal the gap left by the installers using polyurethane caulking.
- You should also seal the brick surface itself to ensure that water isn’t coming through by osmosis.
- Deteriorating mortar joints should be repaired before applying a commercial-grade masonry waterproofing compound.