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Safety Tips

Fuels: Correct Fuel, Correct Use

It is very important to burn the correct fuels on your solid fuel appliance. Using the right fuel will help keep your fire and chimney good condition and you’ll get the most efficient use from it.

The chimney liner fitted must be suitable for the fuel you want to burn or the fuel must be suitable for the existing liner. Using the wrong type of fuel on a liner will reduce the life of the liner considerably due to increased corrosion. This can create a dangerous situation.

If burning wood it must be dry , about 20% or less. Burning wet wood produces poor heat, much more pollution and can block the chimney. The risk of chimney fire will also increase.
Beware of the word “seasoning”. You can buy logs from many sources but the moisture content is often too high for modern efficient appliances.

Wood storage is very important. It’s best kept in a dry store with good ventilation allowing air to get round it. Correctly stacked logs will continue to lose internal moisture even if they are rained on from time to time. That said, the best store will be under some sort of shelter that keeps the rain off and allows plenty of air to circulate.

If the wood is not kept aired then it will start to decay. It will have a reduced heat output and may take on moisture.

Using wrong or poor quality fuel is bad for your chimney, bad for the environment and bad for your wallet.


It is very important to allow your solid fuel appliance breath properly or the flue will be unable to take away the fumes effectively. Inadequate ventilation can lead to smoking back or slow gas speed inside the fire and chimney. The chimney can soot up much faster. Insufficient air flow will also lead to incomplete combustion, resulting in potential increased levels of carbon monoxide.

Ventilation requirements

Open Fires

In the case of an open fire with or without boiler, air opening/s with a total free area of at least 50 percent of the throat opening area should be provided. This is usually 16,500mm2 for a typical open fire. This is ventilation to the room from outside the building.

Closed Appliances

Houses built before 2008 normally have a 5KW heat output allowance without the need for a vent. If the stove is bigger than 5KW a vent must be fitted. The vent needs to be 550mm2 per KW over the 5KW. This means an 8KW stove would need a vent of 1,650mm2.

If the house was built after 2008 then a vent needs to be fitted that is 550mm2 per KW. So an 8KW stove in a new build would need a vent about 4,400mm2 or as advised by the appliance manufacturer – whichever is the greater.
NOTE: It is sometimes necessary to fit a vent in an older property with a 5KW stove if there is not sufficient air to the room, or, if the property had undergone significant draught proofing or heat loss prevention measures such as double glazing, cavity wall insulation etc.

Your Guild sweep will be able to advise you on your ventilation requirements.

Preventing Chimney Fires

There were around 5000 reported chimney fires 2014 – 2015. The real number will be far greater as not all fires result in an emergency call. Also, as professional sweeps, we know that some customers have smaller chimney fires they are unaware of. Chimney fires can be slow and quiet or burn explosively – noisy and dramatic enough to be detected by neighbours or passers-by. Flames or dense smoke may shoot from the top of the chimney.

A fierce chimney fire will most likely cause damage. This damage may not be apparent at first and everything may seem fine. Do not use the appliance / chimney until a full survey has been carried out and a report produced. This will often require the use of specialist CCTV surveying equipment

Chimney fires don’t have to happen. Here are some ways to avoid them:

Use seasoned woods only with a water content of less than 20%. A moisture meter is very useful.

Build smaller, hotter fires that burn more completely.

Never burn cardboard boxes, waste paper or Christmas trees. These can start a chimney fire as bits can get sucked up the flue, setting fire to soot or tar in the chimney

Burn recommended fuels ONLY and NEVER use your fire for waste disposal. This can start chimney fires and produces toxic chemicals.

If you are unsure check the manufacturer’s instructions or ask your stove supplier. Your local fuel merchant may also be able to give you advice as of course will your Guild sweep.

If you have a thatch property it is very important to follow your insurance company recommendations and Local Authority guidelines.

Make sure you are aware of the frequency that your chimney must be swept in order to comply with your insurance policy. Your Guild sweep may advise a more regular sweeping frequency than your insurance company requires depending on your situation and what they find in your chimney.

Damaged Chimneys – Stacks, Liners etc

The two main reasons for damage to a chimney stack are:

  • A chimney fire
  • Weathering with age

A chimney is built in the most exposed part of the house. Sun, wind, rain and frost weathers it for years, and then we light fires under it and fill it full of corrosive soot that eats away at it from the inside. It is no wonder that it needs maintenance from time to time.

The chimney’s other big problem is that it is built on top of the house where the homeowner does not tend to look. Only when things go wrong with it does it get looked at and by this time the damage is more advanced than it needs to be, having not been inspected regularly. Your local Guild sweep will always visually check your stack (usually with binoculars) before sweeping.
Damage to the chimney stack and flue can affect the performance of your chimney and reduce its ability to remove harmful combustion gasses. Flue damage can also create leaks into bedrooms or the loft area which can result in injury or death in extreme cases – see Carbon Monoxide. Following a chimney fire the Guild strongly recommends that a full survey is carried out on the installation and flue before it is used again. If a chimney has not been used for many years it also makes sense to have it surveyed.

There are a fair number of Guild members who have the required training, equipment and insurance to undertake this work for you. See their individual profiles for services offered.

The chimney / flue terminals pictured below MUST NOT be used on any live appliance. They are for redundant chimneys only.


Doc J – Building Regs

Approved document J is the section of the building regulations that relate to heat producing appliances in domestic properties. It has sections for solid fuel, gas and oil. Your local Guild sweep is trained in all aspects of document J that relate to your fire / woodburner and chimney and will be able to give you guidance.

Click here to download Document J



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