REPAIRING A FIREPLACE

AN OPEN FIRE PROVIDES REAL COMFORT IN COLD WEATHER; IF NOT BEING USED, A SCREEN OR LARGE PLANT PLACED THERE CAN PROVIDE AN ATTRACTIVE FOCAL POINT FOR THE ROOM. IF YOUR FIREPLACE IS SHOWING SIGNS OF WEAR OR DAMAGE, YOU CAN CARRY OUT REPAIRS QUITE EASILY.

REPAIRING HEARTH AND SURROUND

Heat and smoke from an open fire can cause tiles in the hearth and surround to crack or the pointing between bricks to deteriorate. If a tile becomes damaged and you manage to find a suitable replacement, remove the old tile by chipping it out with a cold chisel and hammer, starting at the centre and working outwards. Fix the replacement tile with mortar, making sure it lies flush with the existing ones.

BRICKWORK For repointing, rake out the old mortar to a depth of about 13mm, remove dust and debris, brush water over the bricks and fill the joints with a new mortar mix of one part Portland cement, three parts hydrated lime and ten parts silver sand; if the fireplace is no longer in use, a mix of one part cement to three parts clean builder’s sand is suitable. It is best to repoint the whole fireplace to ensure a uniform effect. To replace a loose brick, use a bolster chisel and club hammer to remove the brick and clean mortar from the cavity and any adjoining bricks. Soak the brick in clean water and apply a layer of mortar to the back and sides. Replace the brick, using small wood strips of equal size top and bottom to hold it in line with the existing bricks. Once the cement has set, remove the strips of wood and repoint.

REPAIRING FIREBACK

Cracks sometimes develop in firebacks and the chimney structure may eventually be weakened due to the penetration of heat and smoke. Repair work is easy, using fireclay cement. The surround should be cold when the work is done, so don’t light a fire for at least 24 hours beforehand. Clean away any soot or dirt from the surface with a stiff brush. Undercut the crack slightly, using a bolster chisel and a club hammer, to ensure the filling is well anchored and rake out any loose material. Soak the cracks thoroughly with water and, before the water dries, trowel in the fireclay cement, making sure the crack is well filled and levelling off as the work proceeds. Allow at least 24 hours before lighting a fire.

REPLACEMENT When a fireback is badly cracked or otherwise damaged it must be removed and a replacement unit fitted. Lever out the fireback with a crowbar or use a club hammer and bolster chisel to break it up. Remove the rubble from behind the base section and hack off the cement, on which the base was bedded, to the concrete below.

On many old firebacks, there will be a manufacturer’s name or reference code which will help when ordering a new unit. The traditional fireback has a central protruding portion called a ‘knee’; on some the knee is too low and causes problems in the final stages of installation when shaping the area which forms the throat to the flue of the chimney. When ordering your new fireback, ask for one which complies with British Standards – this will ensure the unit supplied has a high knee and is made to modem dimensions to suit a modern open fire. The quality of the fireback is another important factor. The old unit may have cracked or suffered general deterioration through age.

Although single-piece firebacks are available, they are best avoided because the fireplace surround must be removed to fit them and they are heavy and awkward to handle. Also, cracking is often caused by heat expanding the lower part of the fireback while the cooler upper part does not expand; in a single-piece unit without space for expansion, cracks will develop. Two-piece units are the most popular, although there are four and six-piece versions. With the two-piece unit, the lower half is free to expand without the rest of the fireback being affected.

Check if there is asbestos rope clipped to the back edges of the fireplace surround. If not, hold two lengths of 13mm asbestos rope, equal to the height of the lintel above the hearth, against the back edges of the surround and place the lower half of the fireback squarely and centrally in the open- ing so the asbestos rope is slightly compressed and held in position. To allow for a small amount of expansion, line the back of the new fireback by pushing corrugated paper or thin strawboard up against it and pack infill material behind it to provide insulation between the fireback and the wall. You will need a solid infilling, not loose rubble; a mix of one part lime, two parts sand and four parts broken brick is suitable. Alternatively use a mix of six parts vemiculite and one part lime, mixed to a paste with water; this has better insulating qualities and is especially useful against an outside wall, through which you could otherwise lose an excessive amount of heat.

Place a length of flat asbestos tape along the top edge of the lower half of the fireback. Unlike fire cement, which is sometimes used to make the joint between the top and bottom pieces of the fireback, asbestos tape will not fall out and it allows for the expansion difference between the two halves. Hold the asbestos rope in place against the back of the fireplace surround, check there is a third length across the top of the fire opening between the lintel and the back of the fireplace and place the top half of the fireback flush on the lower portion or set it back by 3mm to avoid its lower edge being burned. On no account should it protrude forwards. Fill in behind the top half with the same mix as before, smoothing the filling level with the top. Fill the space all round the top of the fireback within the chimney with a mortar mix of four parts sharp sand to one part cement to give an even slope of at least 45 degrees from the knee to the throat -you should end up with a smooth line running from the knee to the back of the flue. You can leave the asbestos rope exposed or hide it by applying a very thin layer of fire cement to smooth out the surface.

LINING THE FIREPLACE OPENING

If your fireplace is disused, instead of filling it in with bricks or a panel you can turn it into an attractive alcove by providing a panelled lining. For this, tongued and grooved panels, veneer plywood, melamine faced boards or plasterboard are suitable materials.

To prevent dust and soot falling into the alcove, you should block off the chimney. Since this cuts off ventilation to the chimney, knock out a brick in the fireplace above the lintel, replace it with an airbrick and screw on a fixed ventilation grille. Use plugs and screws to fix 50 x 25mm battens to the sides and back of the fireplace opening so the bottom edges of the battens are flush with the bottom of the fireplace lintel, and screw a piece of resin-bonded plywood to the battens to seal off the chimney. Install a framework of 50 x 25mm battens in the fireplace opening and fix decorative panels to the framework with impact adhesive. Warning Don’t attempt to leave out the timber framework and glue the panels directly to the bricks, since the sooty surface of the bricks prevents secure fixing and the panelling in the recess will not stay in place.

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