hvac duct through fire wall
 

i'm thinking replacing furnace & duct in garage.

The garage to living space wall needs to be fire rated. The ducts will be running right through that wall. How do you maintain fire seal around the ducts (or anything else that goes through the wall for that matter)?

also the part of the duct thats in the garage needs to be 26 gauge with min R4 insulation. Is that right?

Fire caulk.

Code will probably call for R6 min insulation, if not R8.

so you spray that in the gap between drywall and duct? Do you ned anything between duct & framing?

also, what if the duct is run along the far upper corner of the garage such that you can only reach 2 of the 4 sides to spray the insulation?

Fire caulk isn't a spray. Its a caulk like you use for sealing a widow.

If you can't get to all the sides. They will probably fail your inspection. And make you redo it.

Best thing for you to do. Is find out from your code department what they want done. Guessing could cost you 1000s.

For rec duct you can screw 1/8" angle around it and mud over with F/C.

Being you are in Cali. you might need a fire damper with break away joints.

Here in Ga. we can hook duct board to a F/D.

And I don't think R4 will fly in Cali.

sorry. for some reason i was thinking about spray insulation.

I haven't installed anything yet. I am just trying to think of all options or issues. I'm trying to find a new location for the furnace, and that corner of the garage is one of the suggestions from the pros.

r u talking about something like this?
http://www.homerepairforum.com/image...amper_w550.JPG

you might need that in Cali.

You know how those liberals are, always worrying about peoples safty.

I would check with your local building codes dept. Another poster mentioned that they may even have rules for furnaces etc because of movement from a possible earthquake.

I realize this isn't going to solve the OP's question but doesn't "Great Stuff" make a red colored spray foam used for fire block?

I don't know.

u mean this stuff?
http://building.dow.com/na/en/produc.../fireblock.htm

Yes that's it. Seems like I saw on Ask This Old House that its the same as the regular foam except its colored red.