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Property Surveying Blog

October 16, 2017

A Guide to Gallows Brackets

Written by Karim El Shenawi-Ali

As a graduate surveyor here at Berry Lodge, whilst carrying out site inspections, I have noticed that the incorrect removal of a Chimney Breast and its support, or sometimes lack of,  is becoming an increasingly common sight.

If left unsupported the Chimney Breast or stack can pose a great risk to the structure of ones property and in some cases can even affect the adjoining properties.

Gallows Brackets are used as a form of support to withstand the remaining load of the Chimney Stack or Chimney Breast above once the Breast below has been removed.

Gallows Brackets, were used from the 1800’s up until present day as a mechanism to support numerous structures, and get their name from the shape of the structure historically used in hanging, ie the gallows!

The purpose of the Gallows Brackets then evolved and was utilised as a support instrument for alternative structures such as Chimney Breasts.

Design of Gallows Brackets

Gallows Brackets are a right angled shaped steel support mechanism used to support the remaining Chimney Breast or Stack above and will be installed onto the party wall directly beneath the remaining element of the Chimney Breast or Stack.

In order for the Gallows Brackets to be installed and be able to support the remaining load left by the stack or Chimney Breast, the following design factors will need to be met.

  • The wall that they are to be fixed to will need to be a minimum of 225mm thick and made of solid brickwork
  • The projecting Chimney Breast must be at the most, 340mm thick
  • The brickwork or mortar must be in a satisfactory condition
  • The height of the Gallows Bracket must be at least 1.5 times the projection of the Chimney Breast

Alternative Method of Supporting a Chimney Breast

Another way of supporting the remaining Chimney Breast or Stack is via the installation of Rolled Steel Beam (RSJ) which provide support on suitable load bearing walls, usually being those walls which run perpendicular to the Stack or Breast.

 

How to install Gallows Brackets

When removing a Chimney Breast, you will need to get building regulations approval for both the method of support and the work being carried out.

As seems to be the case within London, different councils have different requirements in place in relation to the installation of gallows brackets and the method of support to be employed.

Some councils require three Gallows Brackets to be installed and others will request that two brackets are fitted.

In order to install the Gallows Brackets, the following materials will be required.

  1. 2-3 Gallows Brackets (based on council requirements)
  2. 1 pre-stressed concrete lintel (9 inches wide) or a metal plate
  3. 6 raw bolts used to bolt in the Gallows Brackets in to the masonry
  4. 1 drill with a 16mm drill bit
  5. Sharp sand and cement mix to use as a dry pack between the top of the lintel and the underside of the brickwork

Once the materials have been purchased, you will need to undertake the following steps to ensure the correct, safe and proper installation of the Gallows Brackets.

  1. Mark and drill 6 holes where the Gallows Brackets are to be placed into the wall. One bracket should be installed underneath both sides of the Chimney Breast or Stack (In addition one installed in the middle if you are using three Gallows Brackets).
  2. Place the Gallows Bracket onto the wall where your previously marked holes have been drilled, insert the raw bolts through the drilled holes, then secure them with a spanner.
  3. Place the 5mm metal plate depending on your method across the top of the Gallows Brackets and below the Chimney Stack.
  4. Carefully mix up the sharp sand and cement at a ratio of 2:1(Dry pack) and insert it between the lintel or steel plate and the brickwork.
  5. Your chimney breast or stack should now be supported sufficiently!

If you would like to see a builder’s eye view of Chimney Breast Removal, I would recommend having a watch of our helpful Party Wall Video, which should give you a better idea of the process

During the works, debris and dust can be disturbed from the adjoining owner’s chimney flue and temporary protection should be installed to an adjoining owner’s property during the course of the Chimney Breast removal to stop any damage to their property.

If you are considering removing your Chimney Breast and would like some impartial advice on how the Party Wall etc Act 1996 applies, get in contact with one of our experienced Party Wall Surveyors and we will be more than happy to walk through the process in greater detail. .