Apply a bead of butyl rubber caulk around three sides of the chimney at the top and set the cut piece of metal on the chimney so the edges line up with the caulk bead.
Sealing an unused chimney thimble.
Firstly remove all of the duct tape and put them in a disposable garbage bag.
Sealing your older unused chimney should not be a complicated task as long as attention is paid to prevention of air intrusion as well as environmental and pest control.
Leaving the duct tapes lying on the roof especially if it is windy will increase your cleanup job later.
Air sealing a chimney can save you over 300 a year on your energy bills.
Consider a chimney liner.
There is one important detail for the top cap.
It must be a complete rain shelter not just the spark cap that is normally on a chimney but at the same time it must not be sealed air tight.
If there s no lining due to the flue then a new one needs to be installed.
You can do it yourself in a few hours for a few bucks.
The proper way to close off a thimble port is with brick and mortar to create a solid and safe enclosure.
Press the metal into the.
Usually unused chimneys are capped off with a bent sheet metal covering and perhaps a wire strap or weight on the top.