8

I would like to replace the bathroom fans that came with my 2019 new construction home. I have successfully replaced the basement bathroom fan and it went well enough. The rest of the fans to be replaced are upstairs, and above them is the attic, which is full of blown in insulation.

When I pull the old fan out, how do I keep the attic insulation from falling through the hole into the bathroom below?

The bathrooms are on the opposite side of the house from the attic access, and the insulation fully covers the joists, so going up to "fix" the insulation when I am done would be a project in itself that I would like to avoid.

Michael Sadowsky
  • 83
  • 4
  • If the fan isn't running it's trivial to replace the motor. If they are running, just leave them alone...you're going to make a big mess. – Steve Wellens Jan 04 '23 at 05:52
  • I'm doing an addition to my house and the 40+ year old blown in insulation has to be _pulled_ out of the walls as we open them. After only 3 years, there will be minimal compaction of your insulation, but there will be some. It might be compact enough to have very little fall out. – FreeMan Jan 04 '23 at 13:23
  • Is there a duct beyond the fan? (I would expect that in a well built house in the UK...) – MikeB Jan 04 '23 at 17:11
  • 1
    @SteveWellens Unfortunately the builder used an extremely loud, and undersized fan. The new fan would be larger than the current minimal fan for the higher CFMs and the better constructed fan that is quieter. Fortunately I do have a 4" duct running to the outside. So nothing will be vented into the attic. – Michael Sadowsky Jan 05 '23 at 04:42
  • Am I missing something or misunderstanding? Can't you just shove the insulation to the side and push it back over the fan when you're done? – Huesmann Jan 06 '23 at 12:25
  • @Huesmann I'm trying to do it from below without hopping joist to joist across the attic. I have 12-18" of blown insulation, the joists are fully covered, and that's a lot to push back in the hole from below. – Michael Sadowsky Jan 06 '23 at 14:38
  • @MichaelSadowsky Ah, OK, that makes some sense (also a lot of insulation!). I don't see a way to do what you want without losing *some* insulation, unless you're able to collect whatever falls through the hole in the ceiling, then somehow take it back up to the attic and throw it back over the new fan. Do you mind if I ask why you want to replace the fans? – Huesmann Jan 06 '23 at 22:18
  • 1
    @Huesmann The builder used the cheapest fans available to check off that the bathroom had a fan. As a result the master bathroom is woefully undersized, honestly the regular bathrooms are probably undersized but proving it would require actual math. They are also as loud as a jet engine. This has been on the honey do list for 3 years. I aborted after buying the fan and finally got around to doing the basement, as practice without insulation falling on me. Now on to the harder fans. – Michael Sadowsky Jan 07 '23 at 23:50
  • 1
    @MichaelSadowsky if they're the cheapass Broan 670, 671, 688, or 689 model, there's a drop-in replacement that's a little less noisy (supposedly 2.5 sones instead of 4.0) and faster (60 cfs instead of 50). Unslot the old motor panel and slot in the new one (box stays in place). But if you've already bought your fan, too late I guess. – Huesmann Jan 08 '23 at 14:19
  • @Huesmann Oh! I only bought the one that went into the basement, to see how it went. I will look closer at what the builder put in. – Michael Sadowsky Jan 09 '23 at 15:06
  • @Huesmann I do have the Broan 688. I found links to the Broan 690 upgrade kit (60 CFS and 3.0 sones), but it seems to be discontinued. – Michael Sadowsky Jan 11 '23 at 04:03
  • 1
    @MichaelSadowsky the Broan QK60S is the kit I used. – Huesmann Jan 11 '23 at 21:50
  • 1
    @Huesmann the QK60S did the trick. Not as drastic of an improvement as I planned on, but given the ease of the pop in swap and the insulation I can see peaking around the fan housing, it's the right solution for now. – Michael Sadowsky Jan 16 '23 at 04:27
  • @MichaelSadowsky yeah, I was a little disappointed too, but sound levels are difficult to compare. At the least I did get a more modern-looking fan cover with the switch. :) – Huesmann Jan 16 '23 at 11:20

5 Answers5

6

I feel your pain. In my location most of the homes have blown in insulation. There is no magic trick to keep the insulation from falling. Do the replacement if you must and replace the insulation if a lot is lost.

RMDman
  • 12,303
  • 2
  • 11
  • 35
4

RMDman is right, but it's very important that you replace the insulation over your fan. If you don't, your fan will constantly leak unconditioned air into your room (in one direction or the other, depending on season). Condensation can occur and cause damage. Your fan may be more noisy and less efficient.

One strategy is to carefully remove the old fan, then build an enclosure with fiberglass batts around the opening, against the blown insulation and roughly the height of the fan housing. Lay one or more batts over the box. It doesn't need to be tight against the fan housing, but it should be reasonably well sealed against drafts. This can be done from below with a little patience and creativity.

Otherwise, this might be a good time to establish a route from your attic access. Lumber securely fastened to the trusses can create a path for work and inspection later.

isherwood
  • 119,766
  • 7
  • 148
  • 349
4

As I noted in another recent post: Depending on why you are doing this, replacing the blower may be a cheaper and easier operation than replacing the whole exhaust fan unit.

If you do need to replace the whole unit: ideally, a suitable fire-resistant box was placed over the fan unit before insulation was blown in, for just this reason. But that doesn't/didn't always happen.

If it didn't, the best answer I have is that you can go up and dig your way to the fan, clear the insulation from around it, do the replacement, possibly install that barrier box, and then shovel insulation back to where it belongs... or, as others have said, just accept that a lot of insulation will fall through, try to capture it in a bag as it falls and/or bag it after it falls, then carry it back up and toss it back into place when you're done.

Hopefully someone else has a more clever solution for that last case, though .

keshlam
  • 22,920
  • 5
  • 43
  • 79
  • Replacing the blower was what I eventually settled on. I was able to remove my Broad 688, and use the Browan QK60S upgrade kit. I went from 50 CFM and 4.0 sones to 60CFM and 2.5 sones. I was hoping for more, but this will do for now. – Michael Sadowsky Jan 16 '23 at 04:39
2

If you only need a temporary cover, tape plastic sheeting to cover the hole from underneath or better and if the hole is small enough an opened garbage bag works best as you can easily close the bag holding anything that may have fallen through. Letting the bag hang down so that the everything goes to the bottom, again making it easier on yourself.

Also be aware that while it may be legal, its extremely stupid to let the air along with the moisture collect in the attic, attach duct work so that the air is exhausted outside of the structure.

Ronald Smith IV
  • 21
  • 1
-2

I attach a galvanized duct to the fan exhaust that extends above the insulation. A plastic flapper valve that easily blows open when the fan is on and closes when the fan is off would be good. I can't remember which hardware store I found these valves at.

blacksmith37
  • 8,143
  • 1
  • 14
  • 30
  • 2
    I'm not sure how this addresses the question. Also, blowing moisture into an attic is not wise, nor often legal. Both exhaust louvers and the fans themselves have flappers, so no need for any additional hardware. – isherwood Jan 04 '23 at 19:36
  • There should be free air circulation in the attic. – blacksmith37 Jan 05 '23 at 01:21
  • 2
    Attic ventilation is intermittent at best, and excess moisture isn't necessarily handled by the static convective air movement usually present. It can easily condense on cool surfaces and cause mold or rot. – isherwood Jan 05 '23 at 13:41