Bricks And Mortar

Home-grown bricks

There are two basic types of brick: place bricks are used on internal walls and the inner faces of external walls while stock bricks, which are of better quality, are used for facing work. Most bricks used in Dublin were made in Ireland and not imported as is often reported.

Straight Victorians

Georgian bricks were handmade, which is why they are often irregular in shape and sometimes quite soft. The reason Victorian bricks have a more regular shape is that they were moulded and cut by machine. They are normally harder and more durable than Georgian bricks because they were fired in better kilns.

Beware of damp

Brick doesn't need a lot of maintenance - a lot of Georgian brick has lasted perfectly well for 200 years - but you do have to watch for decay because it can lead to a lot of problems, a major one being damp. If rain water runs down your brickwork it will damage the surface and can wash the mortar out of joints.

Use lime, not cement

Lime mortars should nearly always be used when repointing a building. Nowadays most builders use cement but this can damage brickwork as cement tends to be harder and more dense than the brick itself. Because it is softer than the brick, lime mortar gives a building more flexibility and allows it to settle over time. This reduces the likelihood of any cracks forming in the building. The density of cement causes moisture within the wall to evaporate through the brick rather than through the mortar joint, which makes the surface of the brick spall (flake off).

Hard crust, soft core

A brick is a bit like a loaf of bread with a hard outer crust and a relatively soft, more porous core. Spalling of the brick surface will leave the core exposed and this can cause damp within the wall. Spalled bricks cannot be treated, they have to be replaced. It often happens at the top of a building - a lot of Georgian parapets have been rebuilt in Dublin.

Repointing exposure

Complete repointing of brickwork is not usually necessary. Parts of a building that often need repointing are exposed areas such as parapet walls, chimneys, beneath window sills and around rainwater goods where water run-off can wash out mortar. Where the mortar is sound, it should be left in place.

Do your homework

When sourcing a contractor to repoint, repair or clean brickwork look around your neighbourhood at buildings which have been recently worked on and, if it's of good quality, ask the owners for the names of the contractors. The local authority conservation officer may also know reputable and conservation-minded contractors.

Contractor contacts

Builders almost invariably use cement mortar because it is easier to work with and if the lime mix is not specified properly, it can fail. To source builders who will do this work, phone around or contact the Georgian Society. Ask for references and look at examples of the builder's work. Companies that specialise in lime include The Traditional Lime Company in Tullow, Co Carlow (0503 51750), Cor Castle Lime Products in Innishannon, Co Cork (021 4776677) and Narrow Water Lime Service, Warrenpoint, Co Down (048 41753073).

Repoint at leisure

You should also do a sample area when repointing as sometimes the mortar is too pale and the colour stands out a mile. You can mix in different coloured sands to achieve the tones you require.

Render it useful

In the 19th and 20th centuries, lots of brick buildings were rendered either because it was fashionable or to protect decayed brick. Now people are keen to remove such renders but you need to determine the condition of the underlying brick. Some buildings were always rendered because they were built with poor quality bricks - there are lots of examples of this in Monkstown and Sandymount. It's pointless taking the render off these. Other buildings were rendered because the brick failed and they needed a protective coat.

Steer clear of sealants

Sometimes you see brick sealants advertised on TV that are supposed to waterproof your home but you should never use one on your brickwork. Bricks need to breathe and if you put a sealant on your wall, any water won't be able to evaporate out through the brick so it will come into the building and be trapped there.

Tolerate grubby bricks

You're better off not cleaning brick as all forms of cleaning will damage it to a certain extent. People who spend a fortune on a large townhouse are often tempted to clean it if the bricks look a bit grubby, but this can be disastrous. The wrong type of cleaning can remove the hard outer crust or make the surface pitted. This makes the brick get even dirtier in a relatively short time. A lot of companies sand-blast brick, which is very damaging.

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The best way of cleaning it is to soften deposits by spraying with water and scrubbing with a brush or using poultices. Ideally, you need to get a sample area cleaned and then leave it for a week or two to see what it looks like but few contractors are prepared to do this so you'll need to phone around. In England you need planning permission to clean a building and in Edinburgh there is an embargo on cleaning.

Emma Cullinan is editor of Select magazine