Identifying Serious Cracks In Walls

From YourSITE.com

Structural
Identifying Serious Cracks In Walls
By John R. Schneider
Mar 10, 2008, 21:29

Q. For the past three years I’ve noticed small hairline cracks forming in the exterior stucco and in some of the walls and ceilings of the interior rooms. At first I wasn’t concerned, but I’ve also noticed some cracking to the foundation that I think just started. The house is 12 years old and on a fairly level lot. How do you tell if the cracks are normal or if they are something to be concerned about? J. M. San Ramon

A. Hairline cracking to interior and exterior surfaces is very common particularly in wood framed construction. Homes are built with many different materials fastened together and supporting one another. Because of the inherent nature of construction, these components must be allowed to move, expand and contract against each other without causing damage.

There are several different forces that can affect the stability of a house, most notably wind and rain. However, the greatest factor influencing the stability of a house is the ground that supports it. When the soil moves, vibrates or settles, so does the house that is built upon it.

Much of the soil in the Bay Area is expansive soil, soil that has a high adobe content. This type of soil has the ability to substantially expand and contract, depending upon its moisture content. For example, during the winter months adobe soil expands due to the increased moisture from all the rains. During the summer months, it dries out and begins to contract and shrink. Right now the soil is basically saturated with water from all of our recent rains, and has expanded more than it was in the fall. This seasonal movement of the soil is usually evident by small hairline cracks that appear in the interior and exterior surfaces of a house.

Cracking in stucco and sheet rock most commonly occurs around window and door openings and the inside corners of walls and ceilings. This is usually where building movement is most evident. This can also be seen whenever there is a joint in the sheetrock, or a change in surface direction, such as from a wall to a ceiling. Much of this cracking is normal, and considered cosmetic in nature.

So how can you tell if a crack is serious? By seeing if the edges of the cracks have shifted past one another. This can be a shifting of the edges in an upward or downward motion, or, a shifting that causes one surface to rise above the other, or a tilting of the surfaces so that the crack is wide at the top and tight at the bottom.

Any crack in sheet rock and stucco surfaces whose edges line up with each other and whose gap is less than 1/16 th of an inch is usually a cosmetic crack. This type of cracking usually starts off as a small crack, and gradually lengthens over periods of time. The proper method of repairing minor cracks can be as simple as filling them with caulking, or re-taping them with joint compound and tape.

A structural, or more serious crack, is one that occurs over a short period of time and is often larger than hairline or cosmetic cracking. It is often more than 1/4 of an inch wide, and the edges of the crack have usually shifted in relationship to one another. This type of cracking can also occur around windows and doors, as well as at the intersection of a wall and a ceiling, and it usually indicates a structural concern.

Large cracks are the result of some sort of “shearing” action, and indicate unusual movement of the framing members or foundation of the house. This is the kind of movement that causes doors and windows to shift out of plumb and not operate properly. It can also cause floors to slope, and tiles to crack.

Cracking of this nature should be investigated by a professional before any repairs are made. Barring structural modifications that were not properly done, the first place to inspect if the house is settling is the foundation and sub area under the house. The foundation is what supports the house, and any movement of the foundation or structural members below the first floor, will telegraph up through the walls and ceilings of the house resulting in cracking. By the time you see large cracking, it is because something below the walls and floors finally settled or moved to a point that the finished surfaces of the house begin to separate.

Settlement to the foundation or structural supports for the house is commonly attributed to poor drainage where water is allowed to pool next to the foundation, and infiltrate under a house. Water draining toward a foundation can cause the foundation or the vertical supports under the house to sink into the soil. If this is the case, correcting the drainage usually minimizes future settlement.

John R. Schneider is a licensed general building contractor and an ICBO certified residential code specialist. He is president of All About Homes, a residential inspection company, and has been performing code and construction consultations since 1985. Readers may address their comments to John Schneider, 24326 Mission Blvd., Suite 7, Hayward, CA 94544, Fax number: 510-537-8666, or on the web at www.allabouthomes.com . Schneider will answer questions of general interest in the paper. He reserves the right to edit the letter for brevity and clarity. Readers are encouraged to contact a competent contractor or code consultant for specific information regarding questions they may have about their home.