This wall is an incredible visual example of how bricks can age.
As a general rule a wet brick wall is not a problem, that is, as long as the water is allowed to evaporate. Water will travel up the brickwork and out to the surface via the path of least resistance.
From left to right:
- Here, the mortar is softer than the brickwork. The water is absorbed and will move out through the mortar joints, and then evaporate. This breaks down the mortar, making the joints between the bricks loose and unstable. However, this is actually okay because we can repoint the wall, which is a relatively easy and inexpensive process.
- As the water moves towards the surface, it brings with it the salt in the cement/bricks. When it evaporates, it leaves the salt on the surface, called efflorescence. This isn’t table salt though, don’t eat it.
- Here the mortar is stronger than the bricks. The water is making the same journey through the wall, but it can’t escape through the mortar, so it goes through the bricks. As the weather cools, the water freezes and expands behind the brick face, causing it to blow. Superficial steps can be taken to consolidate the wall, but it’s likely this will not look very aesthetically pleasing. Re-building the wall with new bricks, or turning the bricks around so the internal face becomes external, is another option, but this is more expensive.