flue pipe clearance

[jfd]

Hi I have a question regarding a 6'' flue pipe coming off an of oil fired burner i want to run the pipe up 5' then run the 7' of horizontal run in between 2 floor joists I would like to surround the exposed wood of the floor joists and the floorboards with 2'' thermal fiber a firesafe insulation and then 1/2''cement backerboard over that screwed to floor boards and 2 side floor joists and then close the bottom with 1/2'' cement board so there is no combustible material exposed to any heat.Is this an acceptable solution for moving the flue pipe up and out of the way of the cabinets that it was running through before?The chaseway built in the ceiling will be open at the mechanicle room end to allow any heat to escape from the chase.The flue is connected to a chimney.It will be accessible for cleaning at the ceiling height Thanks for your thoughts John

[Hearthman]

18" clearance to combustibles off single walled pipe for oil. Your clearance reduction system would allow a 50% reduction to the sides and only 33% to the ceiling above. That means your pipe could not fit in a joist bay.

If you use type 'L' vent for oil, it carries a 9" clearance to combustibles. That means that with your clearance reduction system, you run the top of your pipe at the breaching to within 6" of the underside of the subfloor above and 4.5" to each side, which would allow for a 6" pipe in a 14.5" ID joist bay. Remember to pitch the vent back to the appliance 1/4" per foot and properly supported.

I strongly advise you have a pro do this for you. Not a DIY project.

Who inspected the chimney to ascertain its suitability? Did they conduct a Level II inspection?