I have a brick chimney that is rather large in size--serving two household units. It has openings for five flues. There is a persistent leak around the base of this chimney where it meets the roof line. I have been advised to have a "cricket" or "saddle" installed to pprevent further leaks. None of the chimney sweeps in this area seem to know anything about this construction. Can anyone provide me with info about a "cricket" or "saddle" for my chimney?