How to clean a chimney or flue


How to clean a chimney 
Chimneys should be cleaned regularly.

Failure to clean a chimney can lead to two main problems – a chimney fire, or an inefficient heater. If left uncleaned, a substance called creosote builds up on the walls of the chimney or flue. If this build-up gets too heavy, it may prevent smoke from properly venting through the chimney and cause a subsequent leak of smoke and dangerous carbon monoxide fumes into your home. The other potential hazard with a creosote build-up in a chimney or flue is a chimney fire. If the creosote catches fire it will burn very intensely, which has the potential to damage the structure of the house or the chimney.

Creosote is a thick black tar-like substance, which obviously makes it difficult to clean. The easiest, cleanest and safest thing to do is to call a professional chimney sweep, although it may be cheaper to do it yourself if it's safe to do so.


Different methods and their advantages

There are two main ways to clean a chimney: from the top down, and from the bottom up. Both methods involve getting an appropriately-sized chimney brush and sending it up and down the chimney. With the top down method, the the fireplace is covered over (or the wood heater is closed, if that's what you have). Next, the chimney cleaner climbs up on the roof and uses a chimney brush to remove creosote and other debris. This method is the 'cleaner' method, but is less safe and should only be carried out by people who have been appropriately trained to work at heights.


The other method is the 'bottom up' method, which requires lying inside the fireplace, and ramming a chimney brush up through the chimney. This method is safer (in that you don't have to climb onto the roof), but is almost guaranteed to cover everything in the room with soot and muck, so if you're considering it you will definitely need to make sure everything's well covered first.


What you will need

  • Some very old clothes
  • A pair of protective glasses
  • Safety gloves
  • A breathing mask or full-faced mask
  • A sturdy ladder (top-down method only)
  • A fireplace cover (top-down method only)
  • A chimney brush
  • A good torch


Note that chimney brushes come in a wide ranges of sizes, shapes and styles, and some variations use detachable rods, weights and ropes. Ensure that you know the inner dimensions of your chimney or flue before buying a brush. The retailer will be able to recommend the right one for your purposes.


Basic preparations

Before you start, it’s important to note that when cleaning your chimney you need to ensure that you wear proper protective clothing, including eye protection, rubber gloves and a mask. Likewise, you should make sure that the fireplace is completely extinguished before you start.

If you don't have the necessary training or safety gear to work safely on a roof, don't risk it - call a professional chimney sweep. Falling off a roof could very easily paralyse or kill you.


Top down method

The first thing you need to do is to open the damper above the fireplace (or the damper on the wood heater), if it's not already open. Next, tightly close off your fireplace. Ensure that your fireplace cover is firmly secured in place. If you can't get your hands on a purpose-built fireplace cover, a sheet of plywood or metal sheeting may suffice. If you're able to make this airtight, it will help you to prevent soot and debris from being spread all around the room.

Next, use the ladder to climb onto the roof, and make sure you're properly anchored using the necessary safety gear. Remove the chimney or flue cowl if you have one. With a steady foothold, lower the chimney brush, sweeping the inside of the chimney. If necessary, add extra detachable poles to the chimney brush to ensure that it reaches all the way to the bottom of the chimney. Once it reaches the bottom, bring it back up. Repeat this several times. Once you're done, shine a torch down the chimney or flue to see if you've missed any significant spots. Next, replace the cowl and carefully return to earth. Remove the fireplace cover and clean the debris from the fireplace.


Bottom up method

If you plan on using a brush from below, you need to be aware that it will definitely leave you and your room in a complete mess - but it is safer than getting on the roof. Before you start, it's a good idea to remove anything from the room that might be damaged by soot (including computers and soft furnishings), and to cover as much of the carpet as possible.

This method is effectively the same as the top down method, but in reverse. Ensure that the damper is open, then push the chimney brush up through the chimney or flue, adding detachable rods as you go until the chimney brush is at the top. Repeat the process a few more times, and then shine a torch up the chimney or flue to see if you've missed any spots. Once you've finished, clean the room up!