I started working on this chimney because of a water leak - the chase top around the chimney cap is about 1" lower than the rim of the chase so water pools around the chimney and leaks. The house was built in 1973 - chase was rebuilt around 2001. Builder sealed the chimney to chase top with roofing cement. Chimney is 9" inside pipe with 13" outer. Is it wrong to seal the outer pipe/terminal cap with roofing cement? I assume is bad since combustibles are to be 2" away from the outer pipe, but not sure if this applies to termination (there seems no indication of heat damage). I understand that air must flow between the chimney pipes to keep the firebox and chimney cool. After removing the cap, I found a sheet metal ring on top that seems to be blocking vents for the air space between the two chimney pipes. The sheet metal ring looks like a formed factory piece, but it seems wrong that it would block the vents. The fireplace hasn't been used for years and won't be used now, so after removing the cap, I covered the opening/chase top with plastic - homeowner said this is fine til spring, and eventually wants it fixed to code (ie no roofing cement sealer around chimney pipe if this is wrong). Any ideas on this? Esp about that ring blocking cooling vents.