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Chimney clearance for cellulose

cmct1181
cmct1181 Member Posts: 3
1940s cape with brick chimney.  Clay liner was in bad shape so an uninsulated SS liner was installed. Oil boiler. Cellulose insulation in attic in contact with chimney. Does the liner make it zero clearance or does the cellulose need to be moved?

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 24,696
    The liner does not make it zero clearance. Check your local code -- fire marshal ("asking for a friend" is always good for a laugh) but at least two inches clear.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    STEVEusaPA
  • ethicalpaul
    ethicalpaul Member Posts: 6,524
    Wow, code really calls for that?

    A brick chimney can get hot enough to ignite fire-resistance cellulose at zero inches but is totally fine as long as the cellulose is 2 inches away???

    NJ Steam Homeowner.
    Free NJ and remote steam advice: https://heatinghelp.com/find-a-contractor/detail/new-jersey-steam-help/
    See my sight glass boiler videos: https://bit.ly/3sZW1el

  • mattmia2
    mattmia2 Member Posts: 10,819
    it has more to do with keeping a chimney fire or other malfunction from turning in to a structure fire than getting hot enough to ignite insulation or framing under normal conditions.
  • cmct1181
    cmct1181 Member Posts: 3
    So if we were to leave it, besides the risk of a chimney fire, does the brick chimney under normal circumstances ever get hot enough to cause combustion? Cellulose says nothing over 194 degrees. 
  • mattmia2
    mattmia2 Member Posts: 10,819
    You should put a baffle in and move it away. Equipment malfunctioning could do it too.
  • JUGHNE
    JUGHNE Member Posts: 11,266
    I have seen a double or triple? walled wood burner chimney pipe get hot enough to ignite the cellulose
    insulation over time.

    The heat will eventually lower the ignition point of cellulose (treated paper) or even wood.

    Often fiberglass insulation is installed around the chimney or recessed lights (which are a real hazard in themselves). But this is what is sometimes done.....not entirely correct....but better than cellulose.

    A plumber left his work light lying in cellulose and it started smoldering within about 30 minutes.
    Mad Dog_2
  • ethicalpaul
    ethicalpaul Member Posts: 6,524
    But was the work light surrounded by bricks??

    NJ Steam Homeowner.
    Free NJ and remote steam advice: https://heatinghelp.com/find-a-contractor/detail/new-jersey-steam-help/
    See my sight glass boiler videos: https://bit.ly/3sZW1el

  • JUGHNE
    JUGHNE Member Posts: 11,266
    edited April 2023
    I see your point, but it was surrounded by cellulose. ;)

    I was just reporting observations.....cellulose is fire retardant treated paper.....not fireproof.

    But brick, old clay liner and SS liner inside, I would not hesitate to wrap the brick with fiberglass.
    ethicalpaul
  • kcopp
    kcopp Member Posts: 4,463
    Rock wool.... cant burn.
    PC7060
  • mattmia2
    mattmia2 Member Posts: 10,819
    kcopp said:

    Rock wool.... cant burn.

    Does house insulation grade rockwool have a binder like fiberglass?
  • cmct1181
    cmct1181 Member Posts: 3
    Thanks everyone. Because we can’t be sure of the condition of the chimney joints, we’re going to be on the safe side and move it away and put Rockwool around. Thanks again for everyone’s help.