How to Block up a Chimney

Chimney problems such as draughts or birds getting in through the top can become frustrating, leading homeowners to want to block the chimney off completely.

Chartered Surveyor London Guides - Contents hide

A chimney is pretty much an open passageway from inside of the home to the outdoors, which becomes a container when it is closed off. Half of the chimney is exposed to indoor temperatures while half is exposed to the temperature outside, which can cause side effects such as condensation and damp on the inside of the chimney when the chimney is blocked off. This is why it’s important to hire a professional to ensure that the chimney is blocked off correctly.

Chimney Damper:

If you do not already have one, the best way to block off your chimney is by using a chimney damper, which can be fitted by a professional. It rests on the top or in the inside of your chimney where it prevents draughts from coming down. There is a cord that comes down the length of the chimney which you can pull to open or close the damper. If you have a traditional fire in your home, the damper can be opened when you light it.

Draught Guards:

A draught guard can be a simple and effective way to prevent draughts from coming down the chimney and into your home. You can purchase draught guards in different sizes to fit your fireplace either online and in-store. Be sure to purchase a guard that is around three inches larger than your measurements on each side of the hole. These guards are designed to stand flush with the opening of your fireplace and can be used whenever you are not using it for a fire.

How Does a Chimney Work?

Chimney Balloons:

Chimney balloons are inflatable, reusable plastic pieces that can be fitted inside the chimney to block any draughts. You will need to have access to the interior of your chimney in order to use one. Start by partially inflating the balloon by blowing air into the plastic tube attached to the handle. Then, place the balloon in the chimney flue, making sure that the balloon is parallel to the opening and fills the entire area. Then, continue blowing up the balloon until it is firmly fitted in the chimney, making sure that it is holding tight once fully inflated before closing the valve on the handle. If you have a working fire, you will need to remember to remove the balloon before using it.