Frequently asked questions

Q. How much ventilation should a chimney provide?

A. There is no exact answer. It depends on how the house is used and has been adapted. Traditional buildings need ventilation to help the fabric breathe and people need it for healthy living. If the house is well sealed then the chimney probably has an important role. However, it is important to ensure that heat is not lost, so it is wise to invest in cowls or chimney pots and minimise openings at the throat of the chimney. Limiting heat loss is achieved by partially blocking the flue by: balloon, register plate with vent holes, closing a damper or panel in front of the opening with a vent.. The best combination is balloon and cap.

Q. My fireplace and chimney is blocked off. Could this lead to damp?

A. It could if there is no ventilation at the top and bottom. Ventilation into the chimney is needed to help remove any moisture. Condensation can form in the chimney above roof level on damp cold brickwork. Similarly if the stack is against an external wall the cold air could result in condensation forming.

Q. I want to reinstate my chimney and fireplace for an open fire? Is this a DIY job?

A. Only if you are very competent and the work is straightforward. It would be wise to get in a specialist as chimneys are very awkward to survey and work on. It can also be difficult to get a fire to draw and therefore work effectively and efficiently. If there are doubts about the structural integrity of the chimney you should consult a structural engineer or building surveyor. Depending on the extent of work, consents may be needed from the local authority; early discussion is advisable.

Q. Do I need consent to install a heating appliance or modify a chimney?

A. Yes, Building Regulations approval is needed under Part J unless carried out by someone registered with a competent person’s scheme. These include members of organisations such as the National Association of Chimney Engineers and HETAS. Consult your local authority’s Conservation Officer to see if listed building consent is needed.

Q. Can I re-use a chimney for a solid fire without a lining?

A. Yes but be careful. A survey will be needed to check for possible leakage. The stack will be subject to greater heating/cooling & chemical compounds in the smoke. Any fossil fuel fire or stove needs ventilation to feed combustion so check if draught-proofing windows and doors may have reduced ventilation. This is important in order to get the fire to draw. A lining is strongly recommended as it maximises the efficiency of the heating and will enable a chimney in uncertain condition to be used.

Q. Can a disused chimney be used for ducts say from kitchens/bathrooms?

A. Yes, these can be vented by airbricks positioned discreetly in the stack. When venting extractors into chimneys – make sure the air duct runs the full distance of flue and is sealed around the point of discharge.

Q. Should I put in a liner if using open fire?

A. It is worth considering, particularly if the chimney is in poor or uncertain condition, as it is essential to safely conduct flue gases (which include carbon monoxide) to the outside. However, it is not always possible to insert a liner if flues are twisted, narrow or contorted by structural movement over the years. Attempting to force down a liner can cause damage. Flexible metal liners can be used but these have a comparatively short life. A detailed inspection is needed and it is important to ensure that the space between the liner and original flue is vented top and bottom.

Q. Do I need to maintain disused flues?

A. Yes, there is a risk of the flues getting blocked by nests and building debris which could lead to damp, smells, staining etc. It is sensible to get the flue swept and get advice from the sweep on how often it will need to be done again.

Q. How do I protect against significant draughts when the fire is not in use?

A. Consider using dampers in the throat of chimney, in flue or at top of chimney. The best ones are open-able with a handle and they should always allow a small air flow when not in use. Gas appliances must always be fixed permanently open

Q. What maintenance/checks should I carry out to the chimney?

A. If you have an open fire you are strongly advised to get the chimney swept regularly to reduce the risk of gases spilling into occupied room or chimney fires. This will also improve the efficiency of the flue. If you are burning smokeless fuels it should be swept annually and quarterly if using wood. All gas appliances plus flues must be checked for safety at least once a year by a CORGI registered installer. It is also a legal requirement for all landlords to check all flues/gas appliances annually.

Q. What is the most efficient way of making use of the fireplace and chimney?

A Make sure the chimney is in good structural condition, get it thoroughly swept and then install a solid fuel heater (that can burn wood) with a liner. This will provide the maximum amount of heating whilst not creating carbon, providing the timber comes from a sustainable source. Building Regulations approval is needed.

Q. I do not use my fireplace or chimney. Should I take it out?

A. If the building is listed you will need consent which may not be given. The chimney, fireplace, the stack and pots are usually important features of a historic building or a conservation area and should be retained. If however, your local authority does allow this, you will need to get Building Regulations approval which may require the advice of a structural engineer.