chimney crown repair. gap between flues
I May be a little late with this but maybe this could help you out. There is a product called "felxible crown" for the repair of chimeny crowns. It's a latex product that if your half-a**** handy you can do yourself. I learned about it when the local chimeny sweep company came out and suggested an application be applied. They quoted a price of $180. I was able to purchase a tub of the product and did it mayself. the product is expensive (180 range) but when in with other neighbors and my cost was 50 bucks.
Best of luck, rredogg