CHIMNEY STACK REMOVAL

Building Control Services

GUIDANCE NOTES

Need for Support

Building Regulations require that buildings remain structurally stable after alterations have been carried out on them. In most instances the removal of part of a chimney stack will require Building Regulation approval and work will need to be done to ensure the remaining part of the stack is properly supported. Below are some examples of possible solutions. If in doubt as to which is most appropriate, check with Building Control. Tel: 01223 457118 or 457122.

NOTE: Some chimneys act as a buttress and provide support to long walls. Please check with Building Control or a structural engineer, before proceeding, to determine if this is the case.

Guide Solutions

Simple steel beam

9 suits party walls of 100mm (4") thickness

9 should not be used where there are more than two flues in the stack

9 used where there are supporting walls at either end of the steel beam (load-bearing walls)

9 recommend this solution only be used where the length of the beam is no more than 3.600m

9 size of the beam can either be accurately calculated and details sent to Building Control or

without calculation, an acceptable option is the use of a min 178x102x25 UB which will normally be sufficient at a span of 3.600m to carry a single stack

9 beam is placed under the outside edge of the stack and parallel with the wall which the stack is on

9 beam must be provided with fire resistance - 30 minutes in dwellings

Purpose made support bracket

(See diagram over page)

9 should not be used on 100mm (4") thick party walls. Please check with Building Control or a Structural Engineer to obtain a designed solution

9 used where there are no suitable load-bearing walls to support a steel beam suits roofspaces

9 design of brackets varies, but one acceptable purpose made gallows bracket is shown overleaf

9 ensure dry packing material is well rammed between u/side of stack and bracket

9 wall must be checked and repaired if needed to ensure bolts have a sound background to fix to

9 unless in roof space, must be provided with fire resistance - 30 minutes dwellings

Triple and large chimney stacks

In situations where there are more than two flues, advice should be sought from a structural engineer to obtain a designed solution. The diagram over the page should not be relied upon.

Unacceptable Solutions

Timber beams

Timber supports should never be used since the long term performance characteristics of timber (structure/deterioration/fire) cannot be guaranteed.

Corbelled brickwork

Corbelling into existing brickwork should not be attempted as it will not be possible to gain a sufficiently strong bond between the new and existing brickwork unless a significant amount of the brickwork can be re-built.

The Party Wall Act 1996

If you are intending to remove a chimney on a wall shared with your neighbour (the party wall) you will most likely have duties and obligations under The Party Wall Act. This is designed to resolve any disputes, which may arise, between neighbours when building work is carried out. The minimum requirements of the Act are that you notify your neighbour of the intended work. The Party Wall Act is not administered by Building Control, but a Government explanatory booklet can be obtained by contacting us on 01223 457118 or 457122 or contact the Government website at www.construction.dltr.gov.uk.bregs

IMPORTANT

Ensure existing wall is checked and made good if necessary before fixing bolts into it

chimney stack being supported

6mm mild steel plate top and back "fillet welded together & 12mm dia bolt holes

min 25mm well rammed packing

.6mm mild steel plate stiffeners at max 450mm c/s fillet welded to top and back

.6no to 80 10mm dia resin anchor bolts/expanding rawl bots (number dependant on width of stack)

Dia: Suggested detail for purpose made chimney support bracket

Note: - This brickwork design is not suitable for 100mm (4 inch) party walls

Further copies of this Guidance Note can be obtained free of charge from:

Building Control, The Guildhall, Cambridge CB2 3QJ Tel: 01223 457118/457122                                 »p

www.cambridge.gov.uk                                         S^J

Revised April 2007

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