When you re done sealing your attic bypasses push the insulation back into place with an old broom handle or stick as you back out of the attic.
How to seal chimney in attic.
This folded leg strengthens the unsupported edge and created a perfect little trough for firestop caulk.
Remember that all chimney flashings need to be masked off prior to applying the sealer.
Some of the repellents will drip down.
Measure and cut the flashing for each side of the chimney using sheet metal cutters.
I installed it upside down with the drop leg pointing up.
If your hatch rests directly on the moldings like ours did add 2 1 2 in wide stops around the opening.
In places to seal the airspace between the ceiling joists and the chimney as shown in the drawing.
Put on work gloves.
As you note the chase on the attic floor is not as much of a problem because your basement and your attic are both inside of your thermal envelope.
After the air sealing work was complete including wiring vent and plumbing penetrations throughout the attic the attic received an r 60 blanket of blown cellulose insulation.
Now pour the water repellent sealer into the low pressure sprayer and spray it evenly all over the chimney.
Set up a cordless drill with a.
You have to start from the bottom and spray the sealant on the bricks evenly.
So you should certainly seal the air leaks around the chimney at this location by installing metal flashing with sealed seams around the chimney on the underside of the rafters.
That material is not allowed to contact the masonry chimney so after blocking the bypass jerome fit pieces of 2 inch roxul mineral wool insulation around the chimney to isolate the masonry from the cellulose.
Sealing an air leak around a chimney in the attic 1.