Fireplaces and chimneys

Fireplaces were the only means of heating in early villas. Many have now been replaced. Old fireplaces can contribute to unevenness in the floor, and can become dangerous if the mortar fails.

Original details

Originally, open fireplaces and coal ranges were the only means of providing heat to the villa, and most incorporated more than one fireplace. Typically, there was a fireplace in the parlour or front room and in the largest bedroom. Additional heating was provided by constructing back-to- back fireplaces where the unit was located on the separating wall between two spaces.

Generally, open fires consisted of a cast iron grate built into a brick fireplace/hearth designed for coal or coke.

The fireplace opening was finished with a cast iron oval or square register, often with tiles set in the register and a kauri or rimu surround. A low hearth, usually tiled with a brass surround, was the predominant style (Figure 1).

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Construction

Chimneys and the fireplace were constructed of unreinforced brick with a lime cement mortar. Firebricks were laid around the grate. 

Chimneys were centrally placed within the wall. This meant that, to ensure the chimney exited through the ridge line, they were occasionally offset within the framed enclosure. 

It was also common for a corner fireplace to have the chimney structure rotate as it rose, to make the chimney face parallel with the eaves line. A wide range of designs were used to finish the top of the chimney (Figures 2-5).

Flashings at the roof cladding were originally lead steeped around the chimney.

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Modifications

Gas heating was used where supply was available, but was not common. Portable electric heating later caused the open fire to fall into disuse, and many are now blanked off.

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Common problems and remedies

Loss of mortar strength

Chimneys can become dangerous as the original lime mortar loses its strength. As part of any renovation project, the condition of any chimney needs to be assessed by a structural engineer. See problems and remedies >> structure.

Cracking

Cracking in chimneys may be caused by ground settlement, past earthquake damage, shrinkage and swelling in expansive clay soils, or corrosion of reinforcing in lintel beams. For more, see Common problems and remedies >> Roofing and cladding.

Uneven floors around chimneys

It is common, in villas, for perimeter piles to fail while chimney foundations remain sound. This causes the floor to ‘hump’ and slope away from the chimney.

On poor ground, the chimney foundation can sink and may also have cracked. 

For more, see repiling and levelling.

Draughts

Open fireplaces can be a source of draughts. This can be remedied by removing or blocking the fireplace. or installing close fire box insert. For more on draughts, see Common problems and remedies >> Internal walls and ceilings.

Rising damp

Moisture being drawn up through brickwork can be a problem with chimneys. For more, see Common problems and remedies >> Roofing and cladding

Rot

In villas, rot is commonly found around brick chimneys. For more, see Common problems and remedies >> Borer, rot and mould.

Fire safety

Chimneys also need to be assessed for fire safety if the fireplaces they serve are to be used for heating.

Also see fire safety.