How do I Raise the Front of a Leaning Brick Fireplace?

Speak to a planning or buildings officer. Invite them to see the fireplace before work begins. Evaluate the existing cracks, leans and failures. Ask which cracks are "active" (not "dormant") because they are more serious. Record what you see in a journal and take a few photographs. Remove furniture or cover with dust sheets. Roll back carpets and rugs.

Strip back any loose, unwanted material such as split bricks carefully, using a chisel and mallet. Keep the area free of rubble as you progress. Wear a dust mask. Sweep the area regularly using a brush. Discard rubble in a skip.

Remove as much of the leaning brickwork as possible without causing the structure to fail. Contact an experienced mason or chimney build professional if you feel you do not have the required experience or confidence of judgement to complete the strip-back yourself. As a general rule, the opening can be 10 times larger than the flue cross section for masonry fireplaces. (See Reference 1).

Support the remaining brickwork using strong wood stakes. Cut the stakes to size using a wood saw so that they support the brickwork but do not push it upwards too much, which would destabilize the fireplace further.

Aim to open the brickwork up all the way to the builder's arch, which is the curved herringbone brick structure above the opening. Chisel out old bricks and bricks which are crumbling. Chisel out old, decaying mortar, because this is the failure within the fireplace structure causing it to lean forward.

Make a decision at this point about whether the structural defects in your brickwork come from below the line of the arch, or above it. If below, begin rebuilding. If above, seek professional assistance and install full scaffolding before removal of more masonry.

Cut new, longer stakes and support the extended fireplace opening temporarily. Measure the width of the builder's arch from end to end using a tape measure. Add half a foot onto each side and record the full value. Order a steel or concrete plinth to fit across the gap you have measured.

Remove extra bricks from both sides where you want to insert the new plinth, with as much of the chimney breast supported as possible. Insert the steel plinth across the gap. Chisel bricks out as you progress. Ask for help if you need the plinth supported at the other end as you work.

Mix fireproof, epoxy mortar with water and sand in a large bucket. Apply to the brickwork around the plinth using a trowel. Level the plinth using a mallet and spirit level. Tap it into place using the mallet. Repoint the brickwork above and below the arch using fresh mortar. Inject mortar into larger gaps using an injection gun to stabilize the chimney and fireplace further.

Rebuild the brickwork if you wish, or retain the new opening and recreate a larger fireplace. Repoint the brickwork above and below the opening, as far as you can see cracks, with fresh mortar. Allow to dry for at least 24-hours before starting a fire in the fireplace.

Install a flue liner to prevent long term damage to the chimney from flue gases and water damage. If a wood burning stove has a diameter of 5-inches, building regulations recommend using a 6-inch liner. (See Reference 2).