There may come a day when you look at a familiar wall and wonder: Were those cracks in the walls always there, or did they just happen? What would cause the plaster to crack like that?
The good news is that, in most cases, cracks in walls don’t reflect anything seriously wrong with your home. Most wall cracks are cosmetic and easy to fix. In this article, you’ll learn how to examine a simple wall crack, and how to make it disappear with an easy and inexpensive repair. You’ll also learn a few signs that could indicate a more serious problem, and what you should do to protect your home investment. If you are ever in doubt, call a Crosstown engineer to do an evaluation of your home before the problem escalates.
The most common cracks in walls are caused by slight movements of the structure known as “settling.” In a new home, the frame and walls are assembled using new materials that can move slightly, as green wood becomes dry and as the weight of the structure settles on the building site.
This slight movement of a rigid wall creates stresses, particularly in the hard parts of the wall. Plaster, brick, and mortar are unable to flex or twist, so the wallboard may come apart at the joint or may crack in a weaker area of the plaster, such as over a door or window.
Cracks in Walls Can Develop in Homes of any Age
If your home is new and the movement was caused by the drying of the building materials or the settling weight of the house, it might be a good idea to wait up to a year to let the house finish this normal process. Otherwise, as the house continues to settle, a repaired crack might re-appear.
Other causes include variations in temperature or humidity levels, which sometimes occur in vacation houses or homes which are vacant for sale. Changing temperatures cause materials to expand and contract, which can crack plaster, bath tiles, and flooring.
A more serious cause of cracks in walls, floors, and ceiling cracks is the movement of the soil under the structure. Extreme cold or heavy rain can cause the ground under the house (or just a part of the house) to sag downward or heave upward, sometimes causing structural damage. How can you tell whether a crack is merely cosmetic or a sign of a more serious problem? Examine the damage closely. If it’s mostly hairline cracks, less than 1/8-inch wide and dry, they are most likely caused by settling and do not merit much worry.
Even when drywall cracks are less than 1/8-inch, you should check closely for any moisture or water damage, which could indicate a roof or wall leak. Look for discoloration near the crack. Feel the drywall panels with your fingertips. If there is any sign of moisture, you will need to locate the leak and call a roofer. If the crack is dry and if there is no reason (such as recent freezes or flooding) to suspect movement of the foundation, then a simple plaster repair is in order.
DIY Wall Repair
In most modern homes, interior walls are assembled using vertical studs which are faced by gypsum wallboard. Large sheets of wallboard cover walls and ceiling and the joints are hidden using tape and plaster compound. A long, straight crack is probably a separation right at the joint between two sheets. When the crack is crooked, you can still use the DIY approach outlined below.
A good repair will require cleaning out the crack with a flat-bladed tool such as a putty knife to remove all loose material. Plaster that has lifted from the wall, loose tape, and any other debris should be scraped away until the remaining material around the crack has tightly adhered to the wall.
Next, the crack should be sanded thoroughly to remove all rough edges, leaving a smooth valley in place of the crack. Then vacuum or sweep away the gypsum dust, wipe the repair site clean with a moist cloth and allow the wallboard to dry.
Wall cracks should not be filled with spackling compound, as that material is best for small holes only. For wallboard, use joint tape and wallboard compound. DIY stores sell joint tape in rolls and compound in 5-gallon buckets. However, it may be possible to buy a repair kit with just the amount you need. The joint tape is a fiberglass netting which reinforces the repair. The compound should be applied in a series of thin layers that are allowed to dry and sanded between each layer.
Pro Tip: If you take your time here, working in thin layers and sanding smooth between each layer, your repair will be invisible and will last for many years. However, if you rush and apply the compound too thickly, it will crack as it dries and the repair will be both visible and weak.
Signs of Potentially Serious Foundation Issues
As noted earlier, if there are signs of moisture, contact a roofer or building contractor. When any cracks in the walls, ceiling cracks, or floor cracks are very long, wider than ¼-inch, or when there is a visible “stair-step” outlining concrete blocks or bricks – these cracks may be indicative of foundation problems and should be evaluated by a foundation engineer.
Foundation engineers are trained to inspect your house and evaluate the entire weight-bearing system which includes the building, the particular type of foundation, characteristics of the underlying soil, and the effects of any external factors such as drought, freezing, or heavy rainfall.
A foundation engineer may find that there are no serious foundation issues necessitating a foundation repair and you can proceed with a cosmetic repair. However, only a qualified professional can evaluate your particular combination of structure, foundation, and local soil, so their advice is well worth a modest fee.