Wierd

 

Sheet metal and duct tape are appropriate materials

 

But harder to work with, and I fear for the duct tape eventaully drying/loosening.

Also the supply register extend into the duct, so it would not fit f there was sheet mental over it.

Thought on my insultion fix?

 

For whatever it's worth, fiberglass wall insulation is not meant to stop air movement. It's just like big pink blanket, only itchier. :grin2:

 

X2, ductboard would be a good material to use. Foil faced out and sealed to the boot with mastic or mastic tape.

 

post pics.
fiber glass insulation filters air it doesn't stop leakage.

materials to use are paint on mastic or mastic tape.

best of luck

 

How would I put the register back on? It extends into the duct about an inch

 

picture?

how did the register come off?
this is a pretty common type duct/supply box with
grill removed & gap sealed with mastic tape.
see pic below:

 

picture?

how did the register come off?
this is a pretty common type duct/supply box with
grill removed & gap sealed with mastic tape.
see pic below:

View attachment 509131

The OP wants to seal the duct's off completely because they aren't being used anymore.

 

my mistake...still, I'd like to see pics.
(and know the story...)

LOL!

 

Look at the OPs latest started threads for the rest of the story. I'd like to see pics as well.

 

I would treat them as "fireblocking" as described in the building codes. Anything penetrating floors/ ceilings/ walls and connecting spaces must be a contained system, such as ducts connected to the HVAC equipment or cap them off as fireblocks. Any ducts taking up space in stud bays on exterior walls must be packed with insulation equivalent to the code requirements for your DOE zone and fireblocked. Ducts not tied into an HVAC system cannot penetrate a ceiling into an attic or garage unless capped as fireblocking then weatherized as the energy code calls for. Openings exposed to the interior would only have to meet the same requirements as the interior wall cladding for that occupancy class. For residential, ordinary drywall, Thermo-Ply or similar materials would suffice. Exposed foam board would not. You cannot pack a duct with fiberglass and leave it like that anymore than you could insulate a stud cavity and not sheath over it--it must be reasonably air tight. Use T-ply gooped to the surface with UL 181 mastic or tape---done. You can paint over it. Don't skin over floor registered with sheet metal. Someone will step on it causing the metal to collapse resulting in an injury to the person and the cover. Covers over floor registers must be able to support a 40 lb per square foot live load plus a 10 lb/sf dead load and not present a trip hazard. If it must ride above the floor, it must be readily distinguished from the surrounding floor and must be at least 3/4" above the surface of the floor.

HTH,

 

I would cut Sheetrock, and set it in a bed of UL181 mastic. Done.

 

Is this a permanent abandonment or very long term? If its that far reaching timewise, take the boots loose and patch the sheetrock. TYou could always leave the boots behind the wall and cut out the patches later.

 

If it's permanent remove the registers and drywall over the hole.

Billygoat beat me to it...