Tuesday, January 10th, 2012 by Cassi Henes
Have you ever wondered why Colorado Springs has so many early homes with brick foundations, or homes from the 1940s through 1970s are brick construction? That's due to two things:
1. Clay is the most common material from which bricks are constructed.
2. The Front Range's soil is mainly a silty clay--perfect for making bricks from
For efficient handling and laying bricks must be small enough and light enough to be picked up by the bricklayer using one hand (leaving the other hand free for the trowel). Bricks are usually laid flat and as a result the effective limit on the width of a brick is set by the distance which can conveniently be spanned between the thumb and fingers of one hand, normally about four inches (about 101 mm). In most cases, the length of a brick is about twice its width, about eight inches (about 203 mm) or slightly more. This allows bricks to be laid bonded in a structure to increase its stability and strength.
The wall is built using alternating courses of stretchers, bricks laid longways and headers, bricks laid crossways. The headers tie the wall together over its width. This is why brick structures have stair step crack patterns when the structure settles. The way that bricks are laid leads the settlement load to pull stretchers and headers apart.
Starting in the twentieth century, the use of brickwork declined in many areas due to earthquakes. The San Francisco earthquake of 1906 revealed the weaknesses of brick buildings in earthquake-prone areas. Most buildings in San Francisco collapsed during the earthquake, due to the cement-based mortar used to hold the bricks together. During seismic events, the mortar cracks and crumbles, and the bricks are no longer held together.
Additionally, the lifespan of mortar is significantly less than the lifespan of brick. Mortar instability and degradation leads ultimately to structural problems like settling, cracking, and bowing! There is a solution to this situation--tuckpointing. Tuckpointing is the removal of the old grout through scraping and reapplying a fresh grout or mortar compound. THis restores the structural integrity of a brick wall; however, it's important to have foundation settling or bowing issues resolved before tuckpointing because many gaps or stair step cracks will shrink during a foundation lift.