How to rebuild a chimney stack

When chimney stacks are poorly maintained and beyond the point of repair, rebuilding or removal of the stack is the only course of action remaining. Here we’ll look at how to rebuild a chimney stack and what is required when undertaking this work. It is highly advisable to seek the help of a professional before attempting work of this nature.

Before starting, consider (with the help of a structural engineer) how much of the chimney you need to rebuild. Costs can be greatly reduced by only replacing upper brick course where that is all that is required. Rebuilding chimneys from the roof line often involves replacement lead flashings which will add considerable expense.

The first thing to consider is access. Working at height represents a significant risk and scaffolding will almost certainly be required to provide a safe working platform from which to carry out chimney repairs.

Removing a chimney stack can create a lot of mess. For working chimneys and where internal openings still exist, it is advisable to cover to prevent dust and debris falling down the chimney stack and causing damage to internal decorations and furniture.

With a safe means of access in place and internal openings covered, it’s time to start demolishing what remains of the existing chimney stack. First remove chimney pots and set aside if you intend to reuse which is normally possible. Next, carefully hack off flaunching and remove bricks and mortar to the desired level.

Now it is time to rebuild the external chimney brickwork and internal flues before replacing flaunching with a strong (3:1) cement mix and re-bedding chimney pots. If cowls were not previously installed, it’s a good idea to do so whilst the chimney is easily accessible via scaffold.

Gutters and valleys should be cleared of debris on completion to prevent blockages. This is best done once the scaffold is taken down and a local gutter cleaning specialist can normally do this from the ground with the help if a gutter vacuum cleaner.

All in all rebuilding a chimney stack is an expensive and disruptive undertaking which can be avoided by carrying out chimney repairs when required. Check chimney stacks periodically for signs of damage. Missing and cracked mortar is a common problem that is easily addressed with repointing when caught early enough but can lead to structural issues when not remediated. Seek the advice and support of a chimney repair specialist to advise on repairs before problems develop into major issues requiring a chimney rebuild.

Related Articles