jotul?
Burning Hunk
Am I understanding correctly from your photos that the chimney is constructed almost the way a traditional fireplace chimney is constructed, but what would be the firebox, damper, and smoke shelf area in a traditional fireplace is now basically a masonry cube to hold a wood stove? If so, I'm guessing that one of the bricklayers on the job got lazy and used some self adhesive rubber flashing and/or water proofing mastic in the masonry crossover that is supporting the flue liner and the rest of the chimney. In Pennsylvania at least, chimney code calls for a solid masonry chimney of al least 8 inches of fired masonry material (brick) with a one inch air space surrounding a terra cotta or steel chimney liner. That forms the core of the chimney. Outside of that the mason can use block or other unfired masonry to fill in the size specs of the chimney until the face brick are applied around the outside. In your construction, I see how they attached the flue pipe the the terra cotta, but there has to be something crossing over the alcove like pre stressed concrete lentils or angle iron to support the core of the chimney as it was being constructed. If there is an air gap the whole way up the chimney between the terra cotta and the fill brick the flashing/mastic could be anywhere and running down the terra cotta as it melts. Or someone threw some flashing in there on top of the masonry crossover to try to guarantee that no water could penetrate the crossover thus ruining the plaster for at least a year or however long the new construction guarantee is in Ireland. Just a guess, but I've seen that kind of stuff on job sites.
