Kitchen Hood Exhaust Insulation

[emalsyd]

I'm installing a welded 16ga black iron duct for a commercial kitchen hood. Do I need to insulate the duct with firewrap. Wanted to make sure I'm reading the mechanical code correctly.

506.3. Grease duct clearances:

Where enclosures are not required, grease duct systems and exhaust equipment serving a Type I hood shall have a clearance to combustible construction of not less than 18"....

So if my grease duct is more than 18" away from any combustibles I don't need to insulate it?

My thought was to insulate with firewrap where I come through the roof then stop the insulation as long as I'm more than 18" from any combustibles.

 

[cdxx139]

Yes, read the fire wrap manufacturer installation requirements, you may need to overlap or double wrap

knowledge is power

 

[berkshire]

Normal practice is to make a drywall lined chase for the duct with the required clearances. On roof penetrations , a ventilated chase with sufficient clearance to meet local code is required. Stop and think about what happens when that duct gets loaded with grease and catches fire.
B.E.

You are judged not by what you know, but by what you can do.

 

[emalsyd]

Should have explained the installation a bit better.

Building is about 18' high. Bottom of hood at 6'6", top 9'6". Wall hood is against ends at 10' high. Duct goes straight up from hood to roof. No combustibles within a few feet, except where we penetrate the metal deck at roof level.

 

[lilliput1]

I recommend using the firewrap insulation from the top of the hood to the roof so it would serve as insulation to prevent condensation on the duct surface during winter when the hood is off.