Closing a fireplace

LAST UPDATED: 10th January 2023 by The Editorial Team

Fireplace being closed

Summary: Step by step guide and video showing how to close a fireplace with a cast-iron surround, close a fireplace with a timber surround, close a fireplace with a tiled surround, close a fireplace with a brick or stone surround, close a fireplace with a raised hearth, brick up an opening, board up an opening and fit a chimney cowl.

How to close a fireplace

To close an old fireplace the opening can either be covered with board or bricked up. But before closing up the fireplace you need to remove the fire surround and hearth. Fire surrounds can be made of cast-iron, timber, brick, stone or tiled.

Support the fireplace with a timber support whilst unscrewing.

A cast-iron surround

  • Cast-iron surrounds are usually fixed to the wall through lugs beneath the plaster. Chip away the plaster to reveal the lugs on either side of the fire surround.
  • A cast-iron surround will be very heavy, so support it with a timber prop before you attempt to undo the screws holding it to the wall.
  • Unscrew the fixing screws but if this is not possible due to corrosion carefully prise the lugs away from the wall.


The surround will be fixed to battens behind it.

A timber surround

  • Locate the filler covering the heads of the screws that fix the surround to battens behind it. If they are difficult to find, strip away the paint or varnish finish to make it easier.
  • Dig out the filler and unscrew the screws.
  • Move the surround out of the way and then remove the battens to which the surround was fixed.
  • There may be an inner tiled surround, which can be removed by following the guidelines in the next section.
A tiled surround will be fixed in place with metal lugs.

A tiled surround

  • A tiled surround generally has a concrete back and is fixed in place with metal lugs, the same method used for cast-iron surrounds.
  • Remove the screws or prise the lugs away from the wall. With someone to assist you carry it outside where you can break it up with a sledgehammer. Wear safety goggles and protective gloves when breaking up the tiled surround.


You will need to chip away at a brick or stone surround to remove it. 

A brick or stone surround

  • First inspect the surround to ensure that it’s not imitation comprising of stone or brick facings cemented to a concrete backing. If it is an imitation stone or brick surround it can be removed using the same method for tiled surrounds.
  • Wear safety goggles to protect the eyes. Starting at the top course, chip away at the mortar with a club hammer and cold chisel to remove the stones or bricks.
  • You may come across metal ties or nails in the mortar joints that are fixed into the wall. These must be removed; any resulting damage to the wall can be repaired with filler later.

A raised hearth

A raised hearth can be constructed of a tiled slab of concrete or made up of a number of stone slabs or bricks. Both types of raised hearth are cemented to an area of concrete in front of the fireplace, and level with the floor, which is known as the constructional hearth.

  • If the raised hearth is of the tiled slab variety, prise it up with a crowbar.
  • The raised hearth made up of individual stones or slabs needs to be broken up by chipping away at the mortar with a club hammer and cold chisel.
  • Do not remove the constructional hearth. Prior to laying any floor covering, a self-levelling compound should be applied to the constructional hearth to create a smooth surface.
An airbrick will need to be inserted in the 2nd or 3rd course to prevent damp.

Bricking up an opening

To brick up the opening of the fireplace follow the basic bricklaying guidelines. Lay the bricks in courses with the face of the bricks level with the original brickwork. This will allow you to plaster over them.

  • If the opening of the fireplace is over 1.2m (4ft) wide, you will need to tooth-in on either side of the gap where the fireplace was positioned. This will tie in the new brickwork with the original wall providing greater strength. To create the teeth effect, remove the half bricks on either side of the fireplace.
  • An airbrick will need to be inserted in the second or third course to stop moisture collecting in the soot and smoke deposits within them and forming damp areas.  If there is a gap at the top of the opening of 25mm (1in) or more, then this can be filled in using slates or part tiles.
  • When the brickwork is finished, plaster over it so the surface ties in with the rest of the wall.
A ventilator plate will need to be fitted unless the opening is linked to a common flue that  serves a fireplace in use.

Boarding up an opening

To block a fireplace up, you can use a piece of plasterboard as an alternative to bricks. The plasterboard will need to be cut correctly so that it fits tightly into the space.

  • Using timber battens 50mm x 50mm (2inx2in) construct a frame around the inside edge of the opening, setting it back slightly to allow for the width of the board.
  • If the fireplace opening is wider than 600mm (2ft), then it may be necessary to fit a vertical central batten that will support the plasterboard in the middle.
  • Screw the plasterboard to the battens so it is perfectly level with the existing wall.
  • A ventilator plate needs to be fitted into the plasterboard towards the bottom of the fireplace in a central position.
  • Reinforce the board further by taping the edges up. Then apply a coat of ready-mix skim plaster to match in with the wall.

If the opening to be closed is linked to a common flue and serves a fireplace that is in use, do not fit a ventilator plate as hot ashes may fall through it. When boarding this opening use fire-check building board.

Chimney cowls

A chimney cowl can be fitted to cap the top of the chimney, which will allow a flow of air to prevent any moisture build up, as well as prevent birds from entering the chimney. There are different types of cowls for different chimneys; your local builders’ merchant will be able to advise you on the type of cowl required.

Tools needed

  • Screwdriver
  • Claw hammer
  • Sledgehammer
  • Safety goggles
  • Club hammer
  • Cold chisel
  • Crowbar
  • Plasterers trowel
  • Brick trowel

Materials needed

  • Filler
  • Self-leveling compound
  • Bricks
  • Plasterboard OR fire-check building board
  • Timber battens
  • Ventilator plate
  • Ready-mix skim plaster
  • Chimney cowl

Closing a fireplace video

Removing a gas fire and bricking up video

Author

The Editorial Team

The Editorial Team at lets-do-diy.com are a team of experts led by Mark Wilson. We have been creating DIY projects, articles, costs guides and product reviews since 2008. For more info see our about page.