Rehabbing A House

Cracks In Walls - Are They Serious?


Concrete, drywall or plaster, cracks can form in any type of wall material. New homes may experience cracking walls due to foundation settling and century homes can develop cracks due to water damage, age is not the only cause of wall cracks. Different building materials will expand and contract at different rates depending on humidity level and foundation movement. While most cracks can be repaired easily some wall cracks signify a possible serious structural issue and may require repair of an underlying structural issue. The following tips should help you identify possible causes and solutions but when in doubt call an expert.

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About Plaster and Drywall Cracks

Drywall is installed in 4 foot by 8 foot sections and plaster is used to seal the joints between each sheet as well as the gap next to a ceiling. Examine the drywall to determine if cracks are forming along horizontal or vertical edges between sheets. If they are, the most common causes of cracks are excessive drying of the plaster and improper or insuficient plaster application. These types of cracks can often be repaired by patching the crack, applying additional plaster, sanding it smooth, and repainting it.

Jagged cracks and cracks that form diagonally in drywall can signify a more serious problem. Drywall is securely fastened to the frame of a wall or ceiling and jagged cracks without the presence of moisture typically signify that the frame or foundation has shifted. Simply patching the crack will only be a temporary fix if the underlying condition has not been resolved. Jagged cracks should be evaluated by a foundation expert or profesional home inspector.

The size of a crack can also help you determine it's severity. Uniform cracks in plaster measuring less than 1/8-inch in thickness are usually harmless while cracks 1/4-inch wide or more, or that are expanding in size, are frequently more serious.

Moisture behind the wall is also a typical cause of wall cracks, examine the area for signs of water damage. If the crack is damp to the touch or is surrounded by yellowing or staining this is a good sign of a moisture related issue. Common causes of cracks with signs of water damage include a leaking roof, a dripping pipe or insuficient moisture barrier behind the wall. IMPORTANT: do not ignore cracks in walls that present with water damage because mold may grow inside the wall and pose a significant health risk.

About Cracks in Stone or Concrete Walls

Stone, concrete and brick walls typically used in outer wall construction can develop cracks over time. Foundation movement is the number one cause of cracks in concrete walls. The settling or heaving of a foundation is normal and most pronounced in the months and years immediately after construction so consider the age of your home in diagnosing a crack. Older homes have completed all of the settling they are likely to do so if a new crack appears try to identify any changing factors. A new road nearby, increased traffic, a new water drainage issue and even tree roots may be the source of new cracks in the walls of older homes.

Inadequate drainage can cause brick walls to crack, especially colder climates where winter temperatures drop below freezing. It's imperitive that a house has proper drainage to remove any excess water from around the foundation. This includes the installation of eaves and downspouts that direct rain water away from the home. Proper grading and rain water management is usually enough to stop water from seeping into a foundation. If the ground next to a foundation becomes saturated with water it will degrade the foundation and, in winter, will put tremendous pressure on the foundation. A telltale sign that this is happening is the formation of new cracks in the walls above a problem area.

Common locations for cracks to appear include the area around windows and doors. A wall crack that takes on the shape of stairs signifies a serious problem with the foundation below it. If not repaired promptly such cracks will increase the severity of the problem by allowing moisture to enter the home. It's time to call a foundation expert to perform an inspection if you are concerned about a potentially serious crack in any outer wall. Putting off an inspection will usually cause any crack in an outer wall to worsen, potentially costing you more money to repair, so don't ignore it.

Cracks in concrete require immediate attention if they are leaking. There are several good concrete sealants and crack repair products on the market but they will only provide temporary repairs if an underlaying condition is not repaired first. A qualified structural engineer can identify the source of cracks in walls and should be consulted before attempting to repair cracks yourself.

Cracks in Walls - Common Causes

  • Foundation movement, settling or heaving
  • A leaking roof or plumbing fixture
  • Improper joint plaster application
  • Extremely dry conditions
  • Sub-standard building construction
  • Inadequate water drainage outside(freezing)
  • Modifications to original home design

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