So, I've had a Quadrafire Grand Voyager wood fireplace insert for about 2 years now. It does a great job but the gaps between the cast iron decorative surround and the stone are becoming an issue with mice coming and going as well as its a tad drafty. I need to search the outside to see how they're getting in but I'd like to seal around it anyway. I tried fireplace calk but the gaps are just too big because the stone is very irregular. Any suggestions?