Right forum? Red "fireblock" caulk around bathroom fans

10 years ago

The modular home builder put this red caulk that is NOT flexible around all the bathroom fans in the house (upstairs and down), I haven't seen it around any of the other electrical (ceiling light boxes) but it's driving me crazy. Most of it has stopped falling in the downstairs powder room and the one finished bathroom (though we do get some inside the cover now and then, and occasional tiny flakes on the floor), but I want to finish the master bath, seems like every time I go in there to try out tile samples, paint colors, or just to get new sheets out of the linen closet, there are more flakes I need to vacuum up, and I just saw what looked like a nail coming out of the fan over the soaking tub, it's a big "splinter" of this stuff.

Builder told me it was fireblocking of some kind, and that I couldn't even change the fans without needing major sheetrock patching (fan installed in powder room is too big for 21sf room - same size as full baths and it sounds like jet engine in there). But we're going on 7 years now (I know, time to finish the master bath) and this stuff is still falling from the ceilings, it CAN'T be doing any good as a sealant, for air penetration or flames!

What do I have to do to dig it all out without causing major damage, and what should I replace it with (I don't know what's required for fire code)?

Comments (7)

energy_rater_la
10 years ago
what about a picture with the cover off the bath fan?
that way we can see what you are dealing with.
2ajsmama
Original Author
10 years ago
Here is the stuff sticking out of fan near socket
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2ajsmama
Original Author
10 years ago
Stuff fallen in top of boxes in shower area of same bath
energy_rater_la
10 years ago
impossible to see.

best guess would be fire rated foam, caulk
doesn't dry & fall into bits, it falls in strips
like it is applied.

rather than try to dig it out, use Hardcast brand
#1402 mastic tape & seal from inside housing
of fan to sheetrock ceiling. this will keep
particles from falling out, and provide an air
seal at the opening cut into the sheetrock.
keep the mastic tape within the area of the
ceiling covered by the cover of the fan.

you do know how to remove the cover of the
fan?
turn off light at light switch.
take off cover for light bulb, remove light bulb,
undo acorn screw. this will allow cover to drop.
holding the cover in place will be the plug in for
the light, which is a regular plug with the outlet
inside of housing. unplug. the metal bulb housing
is seperate from plastic cover.

(this is the pic I was asking for...)

hardcast mastic 1402 tape is available at hvac
supply & is the best product I've found in 15+ years
to seal metal to sheetrock (& many other surfaces)
surfaces must be clean & dry.

while I don't have a pic of a sealed housing for
bath fan, it is the same process as for sealing supply
boxes (for hvac) to ceilings. below is pic.

best of luck.

best of luck.
2ajsmama
Original Author
10 years ago
Sorry, wasn't sure what you meant by "cover" and the lens/light cover had fallen off so I just snapped that photo. Here's another, so you see what I saw when walked into room, that "splinter" poking out
2ajsmama
Original Author
10 years ago
Got the stepstool and was barely able to reach to get bulb out and cover off (I'm short). DH will have to tape the edges like you showed (thx). He's got some sort of REAL duct tape leftover from HVAC installer (modular factory did the bath fans). All sorts of red and white dust and particles fell on me when I took this down - looked like joint compound in there too?

I'd actually like to replace this fan with a more decorative one I bought (I had bought 3 of them but returned 2 when he said I couldn't replace, this one was open box so couldn't return). Is that possible or am I going to make a mess? Looks like most of the stuff has fallen out. I could just try to get a longer post on this to add glass dome light instead of the plastic lens (that fell off). Just 1 bulb instead of 2, but no replacing the fan. Powder room fan will have to do until we get old and turn the LR into MBR and the powder room/hall/coat closet into MBA, then the fan will probably be the right size (if it's still working).
2ajsmama
Original Author
10 years ago
ceiling shot

Guess we know where there might be some air leaks. I don't think they used this stuff around the ceiling fan J-boxes (didn't see it when we installed - have 4 ceiling fans upstairs), hall lights (2) or smokes (6). Going to have to pull all those down now (fans are a pain)? Tape the edges or if no crumbling foam, is there a specific foam (not white expanding foam insulation I put around windows) we should use?

I assume the HVAC guys sealed the edges of the vents/ductwork just like they sealed joints (and insulated ductwork in the kneewalls of the unfinished, vented attic)?