Poujoulat Wales has noticed on many forums that people believe that they can take down their chimney stack of their own accord. Whilst it is true that you can remove your own chimney stack, you have to do it in accordance with Building Regulations. Many people are unaware that you need to have Building Regulations in order to take down a chimney stack.
They are in place in order to make sure that a building remains structurally sound after alterations have been carried out on them. If you are removing part or all of your chimney stack you will need to seek the approval of Building Regulations. They will ensure that the work that is carried out on the chimney stack leaves part of the stack or the wall itself fully supported afterwards. So here we will advise you on what you need to do to successfully removal all or part of your chimney.
Firstly you will need to make an application to Building Control and all of the work that you carry out has to comply with Building Regulations. Therefore if you have a ground floor chimney breast and intend on removing it you will have to purchase suitable beams that are able to carry the weight of both the chimney stack and the chimney breast on the first floor. If this is not carried out correctly then it could eventually result in the wall bring pulled over.
If you have a chimney breast that is supporting a long wall then you will need the help of a structural engineer. He or she will need to make a design for you and it will have to be submitted to Building Control before any work commences.
If your chimney breast is on a shared wall with your neighbour then the process is slightly different. The shared wall is referred to as a party wall and so there maybe restrictions under the Party Wall Act 1996. This Act is in place just in case any disputes occur between neighbours whilst the work is carried out on your chimney breast.
Removing Your Chimney
Whether your chimney is on the ground floor or first floor, if you are removing it the chimney has to be adequately supported. The stack has to be fully supported and this is done via a gallows bracket.
A gallows bracket can only be used if:
• The chimney stack is not totally vertical
• Your neighbour’s chimney breast has not been removed. If you notice that it has then you will have to seek planning permission because the whole of the chimney above the roof has to be removed and the roof repaired.
• The party wall that the gallows bracket will support will have to be at least 215mm thick and all of the brickwork of the wall has to be in structurally sound condition.
• The depth of the chimney breast should not be more than 340mm.
• Your house should not be more than two storeys, which houses your chimney.
• If there is a party wall then the notices need to be served on your neighbour as according to the Party Wall Act.
• The maximum width of a chimney breast for three brackets to support is 1200mm, that is with two flues. If your chimney breast is wider than this, then again you will have to consult with a structural engineer.
Chimney Stack Considerations
All bolts used are required to be drilled into good solid brickwork and not mortar joints. Then a plate has to be placed on top of the brackets so that debris and soot does not fall into what is left of the chimney.
Your remaining chimney breast that is below the roof line has to be greater or equal to the brickwork in the stack above the roof.
You also have to ensure that condensation or even rain that travels down the flue is dried out by natural convection. To enable this to happen you have to have a chimney pot that is preferably capped with a ventilated cowl and an air brick inserted at lower level.
All members that form the bracket have to be 75mm by 75mm by 6mm mild steel angles and they have to have 6mm fillet shop welded joints and the angles have to be pre-drilled.
If you have a concrete fireplace hearth on the first floor of your property then this will have to be removed. You will also have to install timber joints and the existing trimming joists should support them adequately.
If, for whatever reason, you cannot install gallows brackets then you will have to consider a steel beam design. Once again if this is the case then you will have to instruct a structural engineer and only they can determine the design of the steel that has to be installed. Your structural engineer will submit structural calculations that will justify the design and size of the steelwork.
Whether you are using steel beams of gallows brackets they should both be provided with 30 minutes fire protection unless they are both fully within your roof.
If the above is adhered to then you should competently remove your chimney legally and safely. If in doubt at any point then Poujoulat Wales always advises you to contact your local council who can then, in turn, put you in touch with your local Building Control department. They can advise you accordingly and ensure that you are adhering to the rules.