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#Chimney masonry stack cracked#
#Chimney masonry stack crack#

The solution is to have chimneys swept regularly.ĭamp from rain pouring down un-capped chimney pots, or from condensing gases, can soak into loose internal masonry and bleed through chimney breast plasterwork causing ugly stains.

Over time, soot and tar can build up inside flues, eventually igniting causing chimney fires.

To prevent such dangers, active flues must be lined with the correct type of flue liner.

The acrid chemicals released in combustion gases eventually eat away at mortar joints causing cracks or holes that can allow poisonous gases to escape into rooms, lofts or adjacent flues.

The airtightness of a flue can be tested using smoke pellets. So it’s essential to check the condition of flues before lighting fires. It is even more dangerous where unlined flues are used for gas or oil-fired appliances that produce deadly, odourless carbon monoxide. with a nest – a build-up of poisonous combustion gases will blow back, re-entering the room. Leaks can sometimes go undetected, particularly within lofts or to adjoining houses. Smoke containing combustion gases from fires is potentially dangerous to human health – both from breathing poisonous fumes and from the risk of fire. Often multiple flues are accommodated within a single chimney with thin internal partitions. They are designed to safely transport smoke and combustion gases out to the external environment, based on the principle that warm air generated by fires naturally rises. Fluesįlues are basically vertical exhaust pipes enclosed by the chimney breast and stack masonry. To protect flues from ingress of rain, a simple stainless steel ‘rain hat’ with an integral bird guard can be fitted.

#Chimney masonry stack cracked#

Where a pot is missing, or has cracked or badly spalled it will need to be replaced. Where severe distortion has occurred to a stack, the only option may be to rebuild at least the upper courses of brickwork. ‘Stay bars’ are the traditional way to secure tall or exposed chimneys, which today take the form of stainless steel tie rods and straps. However where significant movement has occurred, the best advice is to consult a structural engineer. Old stacks are rarely perfectly vertical, so a small amount of leaning is not unusual. Redundant stacksĭisused chimneys should be capped to restrict the ingress of rain, and also properly vented to prevent damp from condensation forming within old flues. If your property has mortar fillets, they are best replaced with leadwork as the mortar is very prone to cracking. Traditional lead flashings are the most effective method to prevent this. Many leaks at roof level occur at junctions to stacks. So damp can sometimes penetrate masonry just below the roofline which can suffer frost erosion and need localised repairs. But old stacks were built of relatively soft brick without a DPC. Modern stacks incorporate a Damp Proof Course (DPC) in the lower courses to prevent any risk of water soaking down through the masonry below the roof level.

#Chimney masonry stack crack#

But after many years of exposure, flaunching can eventually crack and disintegrate. The flaunching is the mass of mortar at the base of the chimney pots that helps secure them in place. There are several areas where periodic attention to chimneys may be required: Flaunching Work should be carried out using suitable access equipment. Chimneysīecause chimney masonry is highly exposed to extreme heat and potentially corrosive flue gases it tends to require more frequent maintenance than the main walls lower down the property. gas fires) must only be carried out by a Gas Safe registered engineer, who must notify Building Control. Note that, by law, the installation of heat producing gas appliances (e.g. But the potential for life-threatening dangers from fire and toxic fumes means that even if you are installing a stove in an existing fireplace or lining a flue the work must comply with the Building Regulations (Part J deals with combustion appliances). However, in Building Regulations terms, new chimneys are basically regarded as small extensions, so adding a new one will require consent. In most cases planning permission isn’t required, unless you want to construct a new chimney stack. Renovating a property sometimes involves re-instating an existing fireplace and perhaps installing a new appliance such as a wood burning stove.