Chimney Integrity/Leakage Tests

Chimney Integrity/Leakage Tests

If you do not know the history of your chimney or reinstating a fireplace that has not been in use for a while - it is important to test the air tightness of the chimney.

 A chimney integrity/leakage test is used to check that the flue will be safe and not leak potentially dangerous gasses into rooms above or an adjacent property.  We advise using specialist equipment to test the integrity of the flue, a Wöhler DP23 testing device measures the leakage of your chimney. Air is pumped into the chimney / flue and the device measures how much air, if any, is leaking out.  A reading of the allowable leakage rate and actual leakage rates are produced - this provides the information needed to establish a pass or fail.

A professional chimney sweep will carry out a smoke draught test with every sweep – this is to test that the chimney will evacuate the gasses freely - It does not test for leaks.

Why would I need a chimney integrity test?

• The history of the chimney is unknown – you may have just moved or reopened a fireplace.
• You suspect smoke may be leaking.
• A neighbour may have fumes leaking into their property.
• Change of use – before you install a new appliance the flue must be tested.
• The appliance hasn’t been used in over 3 years.
• A party wall agreement may request that a test is performed before and after any building works.
• If you have problems with your flue.

The chimney is always swept prior to any test as debris can conceal small cracks. Sweeping also allows the chimney height to be measured - we need this information to calculate the test result.

An alternative method to test a flue’s integrity is a ‘Smoke Test 1’. This involves lighting an appropriate number of smoke pellets into the fireplace. As the smoke begins to evacuate the terminal and opening are sealed and the full length of the flue is visually inspected for leaks. This type of test is very subjective and human error is a significant factor; some leaks are too small to see. Roof access is always necessary, the tester requires access to all floors including loft spaces and adjacent properties. This can be problematic in shared properties.

Advantages to using a testing device.

• The terminal can be sealed from the ground using a specialist bladder – ideal if roof access is difficult.
• There is no need to have access to other floors or properties.
• Eliminates the possibility of human error.
• A print out of the result is produced and signed by the tester.
• The BSEN 1443 is the only recognised method of testing in many European countries, smoke integrity tests are not allowed.
• This service usually takes around 90 minutes.

For more information about pressure tests, call 0208 351 7164 or contact us online now at