Birds nesting in my chimney – what should I do?

We definitely know it’s Spring, because yesterday we had four emergency cowl fitting requests in one day!

If you have birds actually nesting in your chimney (as in: there’s chicks), there’s not a lot you can do until they decide to leave. Once they have left though, you can swing into action.

If the birds are nesting in an unused chimney, you can make sure they’ve left (along with any fledglings), then cap-off the chimney (adding a vent, to prevent damp problems).

If however, the birds are nesting at the top of a chimney you do use (a live chimney), then the first thing you need to do is get a good chimney sweep. Birds (especially rooks) can use an enormous amount of twigs, and practically fill an entire chimney. It can take hours to clear, but if it’s not all taken out, it can represent a serious fire risk.

Once the chimney is clear, you need to put on a bird-proof cowl. We use stainless steel bird cowls, as we’ve seen birds rip off chicken wire in about three minutes flat.

If your chimney is lined with a metal liner, it is unlikely that birds will nest in it, as they don’t seem to like the hanging pot cowl used to secure the liner. If you have a bird go down your liner, we’d recommend you have a smoke pressure test to check the liner is still intact.

We charge a fixed fee for supplying and fitting cowls – do call us for a price: 01295 738 144.

JackdawA handsome Jackdaw – big fan of living in chimneys!

(Photo from


What’s A Smoke Pressure Test?

A smoke pressure test is designed to test the integrity of your chimney or liner. Without the test, you don’t know whether your chimney needs work (or lining), or if your liner needs replacing.

How Does The Test Work?

The test is very simple. A bung is fitted to the top of the chimney and smoke pellets are lit in the appliance. We then follow the chimney through the property, looking for signs of smoke. The pellets reek terribly, and have very black smoke – certainly can’t be missed if they escape into the house.

Who Does The Test?

Anyone could do the test assuming they could get on the roof to block and unblock the chimney. However, only a building inspector, certified chimney sweep or HETAS-registered installer could sign the chimney off as safe and complying with building regulations.

How Much Does It Cost?

If you’re using us, that depends. We smoke pressure test any property in which we’re installing a stove without a new liner. If you call us out specifically to smoke-pressure test a chimney, and not install a stove on the same day, our prices start from £100, depending on the amount of fireplaces, height of a property (bungalows are cheaper than four-storey town houses!). Some properties we may not be able to test at all without scaffolding (depending on roof line, height and position of chimney top).


  • The chimney really should be swept before testing. If there is a blockage preventing the smoke from reaching every inch of the chimney or liner, then breaches in the cement or stone work might not be detected.
  • A Smoke Pressure Test is not a Draw Test. For further information on Draw Tests and what they’re used for, please feel free to contact us.
  • A chimney that has passed the Smoke Pressure Test may still need lining or re-lining and insulating, if you are having problems with draw, damp, sooty smells or soot leech.

Further Information can be found at the following places

British Flue and Chimney Manufacturers’ Association

HETAS pamphlet for flues and chimneys


The smoke pellets Stevie uses - not to be confused with marshmellows!
The smoke pellets Stevie uses – not to be confused with marshmellows!