All about smoke tests

Chimney sweep on roof

Has your chimney sweep recommended a full health check? Have you noticed smoke leaking into your home? A smoke test can help you get the answers you need. Smoke testing is a common way to check the health of a chimney.  In our guide below, we share some common questions about smoke tests.

What is a smoke test?

A smoke test determines the health of a chimney.  Smoke tests identify any faults which would cause fumes to escape during the normal operation of the appliance and chimney.

When should I get a smoke test?

It is recommended to complete a smoke test when there is a doubt about the condition, an old chimney is to be reused and during the construction of masonry chimneys.

Who can complete my smoke test?

All smoke test should be completed by a qualified person as outlined by European Standard BSEN 15287-1 for open fires and BSEN 15287-2 for room sealed appliances.  There is a separate method for gas fires.

How is a smoke test completed?

Chimney capped for smoke test

  1. For stoves and open fires, place smoke pellets in the opening. A qualified person will know how many pellets are required.
  2. Ignite the pellets and when burning, seal the appliance.  For stoves, close all doors, ash pit cover and vents.  For open fires, cover the opening with a board or plate sealed at the edges.
  3. Once smoke rises from the chimney, cap the opening (flue, terminal or pot) using a plastic bag sealed with tape.
  4. Examine the full length of the chimney for smoke leakage. Check for signs of smoke leakage from wall cavities, at the sides, back of the chimney, openings around windows near to the chimney and the roof space area.


A qualified chimney engineer will inform you of your results.  Minor leakage detected is not a major risk when the appliance is used in accordance with the manual, providing the leakage does not indicate a fault which could get worse. Heavy smoke leakage must be investigated and repaired.  Common causes include broken components, incorrect fitting and incomplete jointing.