Gas Fireplace Exaust Clearance

The is a natural gas fireplace that uses a flexible double wall exhaust pipe. 7" outer 4" inner (see pictures). It needs to be reconnected to the exhaust in the in the sheeting/siding. How much clearance it requited between the sheeting and the outer wall of the pipe? Hope that make sense.



I was able to get a hold of the manufacture of the fireplace and the duct and they said 3" on top and 1" on sides and bottom. I should be good. I have about 3" on all sides. Thanks.