Does thermal bridging from metal fixings in promafour board cause problems?

Dodderbug

Hi, ive recently had an inset stove installed into an old concrete fireplace with promafour board as backing. The promafour is secured with metal mushroom fixings with a skim coat of plaster over the entire board. Dark patches have started to appear over some of the fixings with one groeing to 8 cm in diameter and then shrinking a little in size when i light the stove. I presume this is due to thermal bridging. My question is, is this normal? If i prime and paint over it will it cause damp issues going forward? Do i need to call the stove installers back in the fix the problem and how big a deal is it to fix? Thanks

Mellor

The thermal bridging from the fixings is not going to be significant. You likely have much much bigger sources of energy leak.

That doesnt mean they are not related to the discolouring, which wouldn't be indicative of thermal bridging imo. Promafour board are typically glued rather than fixed with mechanical fixings