Then use a paintbrush to apply duct mastic to the joints where an elbow connects to a duct.
Seal seams around lights and vents in attic for insulation.
Now it will be safe to heap insulation onto that spot.
After sealing the areas just push the insulation back into place.
Apply the sealant around the cable and along the edge of the cover where it rests on the ceiling.
For larger holes filler material may be needed.
If you have blown insulation a small rake can be helpful to level it back into place.
To apply insulation measure the circumference of the duct and use a utility knife to cut foil faced fiberglass insulation to the proper size add a couple of inches so the ends can be drawn together easily.
Push back the insulation and scoop it out of the soffits.
How to air seal recessed can lights from the inside.
To seal these openings use caulk or spray foam.
It s easy to overlook electrical wires ducts pipes and vents in the attic but the openings around these are holes can compromise the air sealing of your attic.
You need to leave at least 3 inches on all sides of the light.
If you have recessed light fixtures in your home you may also have a significant volume of conditioned air escaping into your attic.
Notch a hole for your wire and spray foam around the bottom and any gaps in the box.
If you are creative you can also use spray foam to glue your boxes together.
Seal the foil to the frame with the caulk adhesive and staple or nail it in place if needed.
Although the insulation is dirty it is still okay to use.
Add or remove insulation from the bag as necessary to ensure it fits.
Attic air sealing and air barriers prior to insulation all gaps cracks seams and penetrations between conditioned and unconditioned space such as gaps around lighting fixtures hvac duct boots electric wiring plumbing pipes and flues shall be sealed with sealants alone e g caulk foam aerosol sealant if the gaps are narrow enough or with rigid blocking material sealed in place with sealants per the sealant manufacturer s instructions.
Soffits may be filled with insulation or covered with cardboard or fiberglass batts.
Now plug the open stud spaces photos 1 and 2 and seal the top of the cavities with reflective foil photo 3.
Use a continuous strip of foil tape to seal off all longitudinal seams along the straight runs of the duct.
Up in the attic clean the ceiling surface around each fixture slit the cover to accommodate the electrical cable and place the cover over the fixture.
There is no need to remove and replace it.
Use expanding foam or caulk to seal the openings around plumbing vent pipes and electrical wires.
Seal fireplace and furnace holes.
Cover the area with insulation again when you re done.
Cut a 24 inch long piece from a batt of iberglass insulation and place it at the bottom of a 13 gallon plastic garbage bag.
So if you have a 4 inch wide by 8 inch tall light you would 10x10x11 box.
