A chimney terminal is the bit right at the top – sometimes known as a cage, cap, cowl, birdguard or ‘chimney thingy’! There are a number of uses:
- Keeping out birds (Jackdaws) who nest in the flue and vermin such as squirrels
- Keeping out rain
- Combating down draught problems
Some homes may not need anything on the chimney – sometimes a chimney pot is sufficient – indeed occasionally even a pot isn’t needed! But anyone with a woodburner, multi-fuel stove, AGA or similar appliance are advised to have a cowl of some type, if only to prevent water ingress – water will rust away the metal box beneath and can mix with the soot to create a corrosive substance in the flue.
Having the correct terminal is important and we frequently see the wrong type fitted and/or fitted incorrectly – perhaps the wrong advice has been given or simply the customer has changed how they use the flue and not considered the other end of their chimney.
Simply put, whatever is fitted to a ‘live’ chimney (one in use) should be installed so that it:
- can be swept into without dislodging it – ensuring that the flue is clear all the way to the top
- allows the safe removal of gases caused by combustion to pass out of the flue
- prevents condensation build up in the flue of a disused chimney
If you use any appliance or open fire you should NOT have this type of terminal on your chimney. They are dangerous as fumes are prevented from escaping quickly enough – they are not designed to be used with a live flue and could result in the build-up of highly poisonous carbon monoxide.
If you have a problem with birds, rain or vermin entry into your chimney – there’s a cowl for that. The silver one on the right can also aid with a down draught (in certain circumstances). There are also a variety of chimney pots and cowls for lined chimneys.
This terminal is a no-no for any live chimney. It doesn’t prevent any birds entering – in fact it’s a lovely shelter for the birds – and the cowl will impede the outflow of fumes. In addition, the design of many clay terminals, which are not intended to get hot, means that the tops can crack and be dislodged in windy conditions or when the chimney is swept. This can damage roof tiles/slates…or worse!
If you need any ‘terminal’ advice contact your local professional qualified chimney sweep or experienced chimney expert builder or woodburner supplier. Whilst a roofer will be able to install a unit they may not have the necessary skills to advise what should be fitted for safety.
Wilkins Chimney Sweep
John Baldacchino in West Cheshire was recently called by a customer who had a nest in a gas flue – this is a really serious danger. If the customer had been using the gas fire there is nowhere for carbon monoxide to escape except to build up in the room – and this could have resulted in deadly carbon monoxide poisoning. This nest was pretty extensive – you can see how close it is to the top of the pot.
This situation was made worse because the customer believed she couldn’t have a nest in the flue as there was a ‘cage’ on the top. Here’s a picture of ‘the cage’. These are ‘affectionately’ known as bird boxes by our team as they offer no protection AGAINST birds but a lovely warm and rain free ‘home’ FOR birds! This terminal was clearly stamped with DO NOT USE ON A GAS FLUE. These terminals are more usually stamped NOT TO BE USED ON FLUES IN USE – and are simply unsuitable for use on anything but a disused chimney. If there is something stamped on a flue terminal there is usually a sound reason for it!
The Wilkins Chimney Sweep team all know what to fit for the appropriate flue. When there is a change of use it is absolutely critical to check that whatever is fitted is fit for purpose.
So please spread the word – don’t rely on someone who has no specialist knowledge of what to install (builders often don’t know the right type to fit – however good they are at building!) and if in doubt, please feel free to contact a Wilkins Chimney Sweep! Whatever you call it – cowl, cage, birdguard, terminal, clay pot thingy – we’ll work out what you need it for and then make the safe recommendation.