Can a blocked chimney cause damp?

Yes, and this is usually related to poor ventilation within the flue. If the chimney has been fully capped off at the top of the stack and the fireplace removed/blocked off within the property, there will be a lack of air within the flue. When the property then warms up, condensation will collect within the flue and usually present itself as damp on or around the chimney breast.

To resolve this issue, it is essential to vent any unused chimney at the top with a suitable cowl and at the bottom with a vent below ceiling height on the chimney breast. If the chimney is already well ventilated it may be that condition of the chimney stack has deteriorated and is allowing some water/moisture to penetrate within and will need addressing.

The distance between the stove and wall is dictated by Building Regulations and the manufacturer’s installation requirements and whether it is made of a combustible material.

Building Regulations do not dictate the distance of a stove from a non-combustible material, however the manufacturer will usually specify a gap of around 50-150mm to any non-combustible material to allow air flow around the stove.

Should the stove be installed in front of a combustible wall, the minimum requirement is dictated by Building Regulations and 300mm clearance is required. The manufacturer may dictate a greater distance and therefore the larger clearance should be adhered to. Alternatively, this distance may be able to be reduced using a heat shield, but again, manufacturer guidelines should be followed.

The most important factor is that the wood is dry and well seasoned, that is left for more than one year before burning. Many woods are improved by prolonged seasoning inparticular oakThere are many opinions, the general consensus is that of commonly available wood ash, beech and very well seasoned oak are best. Other wood that burns well are birch, hawthorn and yew. Some burn well but are only recommended for stoves with closed doors – horse chestnut for instance. Less available wood that burn well include hornbeam, apple, hazel and robinia. Be wary of tarry woods like pine, eucalyptus and cedar which can leave more tarry deposits in your flue than other woods.

OK you’ve checked that the flue is clear by sweeping. Good dry hardwood will always burn given a chance. Start with a small fire of paper and dry, small kindling to begin the process of heating up the flue. As the flue heats up the up draught will be improved and more oxygen supplied to the fire. If you are using a stove keep the door to the stove very slightly ajar and you will hear as well as see an improved draught. Only add larger logs once the fire is burning really well. It is essential that there is enough draught for the fire and this is improved by sufficient oxygen supply into the room and into the fire. Most stoves have adjustable controls that regulate the flow of air, make sure you are familiar with the operation of them. Once the fire is going, replenish the fuel at regular intervals and slowly reduce the draught in a stove using the controls. Once at optimum temperature the flames in a stove look more like hot gases and this suggests the stove is burning efficiently.

The first thing is to consider the source of the smell. Smoke can arrive by any number of methods including through open windows, down neighbouring flues and through leaking flues. First ascertain where the smell is strongest, is the smell there only when the fire is lit. Is there always a smell upstairs when the fire is lit or just when the wind is in a certain direction. With the fire lit, go outside and watch the behaviour of the smoke as it leaves the pot. Does any appear to be drawn down neighbouring pots?

If there are no clear signs of the cause, get the flue swept and if the problem persists then it is likely that the flue is leaking and will need lining. A CCTV survey may confirm this.

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