How To Seal Chimney In Attic

Measure and cut the flashing for each side of the chimney using sheet metal cutters.

How to seal chimney in attic.

You have to start from the bottom and spray the sealant on the bricks evenly. This folded leg strengthens the unsupported edge and created a perfect little trough for firestop caulk. Access the attic through a crawl space in the ceiling using a stepladder or use or the attic stairs. Sealing an air leak around a chimney in the attic 1.

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. In places to seal the airspace between the ceiling joists and the chimney as shown in the drawing. 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.

Remember that all chimney flashings need to be masked off prior to applying the sealer. I installed it upside down with the drop leg pointing up. I used pieces of various widths up to 6 in. Put on work gloves.

Some of the repellents will drip down. Now pour the water repellent sealer into the low pressure sprayer and spray it evenly all over the chimney. If your hatch rests directly on the moldings like ours did add 2 1 2 in wide stops around the opening. 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.