If you have ever driven through older neighbourhoods, where the brick homes date back to the early 1900s, you have seen how beautiful painted brick walls can be. Some people choose vibrant colours as a change from the standard brick colour or to accent more neutral walls. The brick walls can last a long time as they don't lose the mortar that is holding them together. With the increased concern about building green, you may be surprised to learn that brick is a very thermal building product. It holds the heat and releases it slowly, reducing heating costs in winter. It also allows the structure to breathe. So when you're painting, it is important to not seal the surface.
Prepare the surface for painting. Any moss growing on the surface or old ivy vine tendrils will need to be scrubbed off. Check all the bricks for soundness. If any are loose they will need to be reset before painting. Look at the mortar to make sure it is not cracking or loose, either. It is also important to note where all the vent holes or weep holes are so you don't block them with paint.
Clean the wall with a power washer to remove the accumulated grit and grime from over the years. You want the surface to be as clean as possible for a good adhesion of the paint. Power washing can damage brick, especially if the brick is very old, so consult a professional if necessary. You may be just as successful with a cleaning solution and scrub brushes.
Choose the paint for your wall. Latex and Portland cement-based paints are most commonly used as they will allow your wall to breath while still resisting water. You local paint dealer should be able to assist you in your choices for the right product for your application. Typically, a primer will be used to help make sure you get the best adhesion from the paint.
Dry the wall completely after cleaning. Since the brick is porous, it will soak up water and will need to be allowed to dry out before you start painting. Trying to paint on a damp wall will only cause problems as the paint will dry blotchy since some areas on the surface of the brick will be wet and pull the paint into the brick.
Apply the coat of primer and allow it to dry for the recommended amount of time, anywhere from 1 hour to 24 hours, depending on the type of paint and the environment. Start at the top and work down both with the primer and the paint. Whatever your roller doesn't coat can be touched up with the paint brush.