Planning for attic sealing and re-insulation
conor_mc
| Posted in General Questions on
I’m planning on removing the rodent infested blown in fiberglass insulation in my attic, air sealing everything that I can, and re-insulating my attic. Everyone seems to like the Tremco acoustical sealant for sealing top plates and vent pipes. How many tubes would you guess I need for sealing an attic for a 3000 sq ft colonial?
I’m planning on using fire caulk for sealing electrical boxes. Any favorite product out there?
Any recommended product for disinfecting the attic after I’ve removed the old insulation?
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Replies
Simplest way to seal electrical boxes is one of the smaller two part spray foam kits (15 board feet ones are great for this). Make sure to check the inside of the device box afterwards and trim any excess foam.
Rest of the sealing is best done with gun foam (I like to use Dow Enerfoam as it won't set in the gun) and a tub duct seal mastic. The mastic is water based, easier clean up and you can apply it with a brush.
Hmm so have people gone away from the acoustical sealant and use the spray foam for more things? I was going to use the spray foam for sealing electrical conduit holes but are people also using that to seal top plates etc?
I think most of us use the foam guns. As I do a lot of 4:12 roofs, I need the 30" gun to reach. Acoustical caulk is for wall plates or things about to be set together under preasure. Very sticky business. I like Purefil 1G or Dap for the better guns available through EFI (Energy Federation, Inc.). A case is 12 cans and each can good for 1200 linear ft of 1/4" bead. Most 1200 sq/ft attics I use about 4 cans.
Thanks for the reply! My roof is 10:12 so I've got some more room to work around in but that's good feedback.
Please be sure to read about Hantavirus before you remove the insulation. Seems to me the dangerous time is while you are cleaning out the attic not so much afterword.
https://www.mayoclinic.org/diseases-conditions/hantavirus-pulmonary-syndrome/symptoms-causes/syc-20351838
Walta
Thanks Walta. Luckily I'm not West of the Mississippi River, but I'll definitely be taking it seriously. Gloves, respirator, and tyvek suit for sure. It would be nice to know if 10% bleach water is sufficient for decontamination or if professional companies use something else.
Will the foam sealing be effective for keeping the rodents out? Or can they easily chew through it an re-invade the attic?
Just about anything is effective. Small rodents are very sensitive to airflow and they search holes that have air movement through them. The foam stops the air movement and it's like there is no hole at all to the rodents. That is unless they've got an active nest, then they'll chew through anything to get to their babies. But for the most part they won't chew through even foam if they don't know the hole goes somewhere. Air sealing really helps control small rodents. For big ones (squirrels, racoons, etc.) you need sheet metal or hardware cloth. You can install hardware cloth across a larger hole and then surround it with spray foam to seal the air leaks.
Interesting info Peter! @Antonio, I've done a lot of work in the basement and outside perimeter of the house putting up xcluder cloth (stainless steel metal mesh) that they can't chew through and that has seemed to help mitigate the mouse issue significantly. I wasn't relying up the spray foam alone to prevent the mice from coming back.
And like Peter said, most times I would push in the xlcuder cloth I would spray foam behind it.