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Chimney Breast Removal

The Benefits

Chimney breast removal can be a very effective way of enlarging rooms in older properties to free up a lot more space iby removal of the chimney breast and hearths.

In a quite small terraced house the floor area gained can increase the value of the property many times more than the actual work will cost.

Chimneys can be removed from the ground floor to the roof including the stack standing above the roof or from just one floor.

When the ground floor chimney breast is removed leaving the rest of the chimney on the upper floors and the stack above the roof the upper parts of the chimney stack must be supported. This also applies if the chimney above the roof has to be retained because local Town Planning rules preclude removal.

The actual work involved in chimney breast removal is fairly straightforward. However it is easy to overlook potential problems and so it is always safer to get a structural engineer's advice before starting.

 

 

Legal Issues

The work must comply with the Building Regulations 2010 and so a submission will be required.

Furthermore , where the chimney is part of the party wall between two properties, the Party Wall etc Act 1996 places certain burdens on the person intending to carry out the work. See www.pentacon.co.uk/party-wall-agreements-notices.html

In many instances it will only be possible to remove a chimney from a Party Wall if the chimney in your neighbours property is retained. And it is likely that Gallows Brackets (see Details below) will only be allowed if the neighbours chimney is retained.

So if advantage is to be taken of a neighbours chimney to allow use of gallows brackets, you are advised to have a written agreement with your neighbour to ensure that remedial works at your expense do not become necessary if they remove their chimney at a subsequent date.

 

 

Technical Issues

There are a number of issues that need to be considered.

1) If chimneys are to be removed the areas of floor that are supported by the chimney can sag and possibly collapse. So they should be supported by new full length floor joists to replace the existing floor joist hearth trimmers where the hearth and breast have been removed.

2) Single or 2 storey houses with external and party walls 225mm thick and with front and back walls less than 9 metres apart may give adequate resistance to lateral loads.

3) For larger buildings a structural engineer may need to check the adequacy of the wall and some form of stiffening or a buttress wall or pier may need to be provided instead of the chimney breast.

4) If parts of the chimney breasts are to be retained, then they need to be well ventilated at the top and the bottom.

5) If the chimney above the roof is to be retained it will need to be fully supported by gallows brackets or by inserting a steel beam or post. These brackets may not acceptable if the chimney does not taper down in size in the roof space.

6) If a recess is found in the wall for the flues it needs to the filled with brickwork to make up the wall locally to the same thickness and density as elsewhere for sound insulation. Typically small recess areas are built up with bricks on edge, which are tied back to the wall with ties at 450mm centres. All joints need to be packed with mortar for their full depth.

7) Fire safety - Typically at least a one-hour fire resistance is required to wall between neighbouring properties. If separation between flues is damaged carbon dioxide/ monoxide poisoning could result from the neighbour’s fires.

8) Damp prevention - To ensure rain and condensation coming down the flue is dried out by natural convection, a ventilated cap is sometimes added to the top of chimney pots and airbricks installed low level.

9) Ventilation to rooms - Building Regulation Part F2 advises rooms to have permanent ventilation of at least 8,000 mm2. Chimneys can provide this.

Gallows Brackets

They look like this:-

 

gallows brackets

 

They can be used when:-

They cannot be used when:-

Some District Councils will not accept gallows brackets or insist on mimimum requirements such as:-


1) A drawing, calculations and specifications for the geometry and fixings

must be provided

2) A minimum bracket depth of 450mm is required.(this reduces the

tensile forces on the top bolt fixing)

3) On party walls any directly adjacent chimney must still be in place and
calculations cannot rely on the neighbours property for stability

4) Chimneys are capped

5) The chimney outstand is less than 340mm

6) The supporting wall is a minimum solid 215mm thick at the fixings

7) Resin anchors must be used on the basis of the recommended loads from the manufacturer for fixing into old brickwork.which may have been subject to dilapidation by, chemical action, heat or weathering

8) Expanding anchors in old masonry are not acceptable as they can

damage the brickwork

9) The wall is confirmed to have bricks of strength greater than 7N/mm2 and is not built using weak lime mortar

10)Resin Anchors are placed in centre of bricks, not in perpends or bed joints or within 25mm of the brick edge and with only one fixing /brick 

11) The fixings must not penetrate an adjacent neighbours flue

12) Fixings are not in an area which formed part of the actual flue

13)The brackets sit fully flush against the brickwork so parging, render or plaster must be removed

14)If used in the roof space the size of the remaining flue below the roof line is greater than that above the roof 

Where to go for Gallows Brackets?

They can be bought from places like Screwfix at about 80 for a pair including VAT.  The problem with buiying brackets like this is that they will never fit perfectly into the space that you have and more importantly the fixing holes are very unlikely to be aligned on the centre line of a brick as is often insisted on by the Building Control Officer.

The galvanising is also unnecessary for indoor use.

And they are really easy to make from  a piece of 50 x 50  x 5  mm angle  - just cut the bits to length  and  get your local garage to weld them  up. Then you can put them in place mark the fixing holes in the middle of bricks, and drill the holes.

Resin anchor fixings can be bought anywhere in places like B & Q

Cost of Chimney Breast Removal

Most chimneys can be removed from ground floor to the roof in about a week by a two man crew.

So with materials the cost should be somewhere be about 3,000 depending on tipping and labour costs in your area.

 

Pentacon Can help with Chimney Breast Removal

Pentacon can assess and design suitable supports, advise on how to ensure your property is safe and prevent any neighbouring buildings from damage and deal with the Party Wall Notices.

Before any work takes place, designs should be submitted to the relevant council building control office and the local authority building control officer will inspect any work that is to be undertaken.

If the work is safe and satisfactory, then a completion certificate will be issued. This document is essential for re-mortgaging, selling or for insurance purposes.

Contact Pentacon

Pentacon would be pleased to help you remove your Chimney Breast removal project.

So give me a call and email me a copy of any photos of the building and the chimney as well as the sizes of the rooms that the chimnhey passes through and any other relevant information.

I will provide free advice in an Email on how much the design fees will be and anything else that you will need to allow for.

Just text or call me on 07557 966 459.

I look forward to hearing from You

 

 

Best Regards

 

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