Cracking in homes is a common concern that can point to structural issues. Cracking can also be quite normal and expected caused by houses settlement over time. Experienced NJ home inspectors encounter numerous types of cracks in foundations, floors, walls and ceilings. Understanding the causation of these cracks and their implications is important in determining whether they are significant or just typical settlement cracking. Good home inspectors should be able to differentiate when cracking is severe and when cracking is typical.
Some of the most prevalent cracks and the most concerning can be cracking that is horizontal in nature. This is especially true in foundation walls. This type of crack in the foundation wall typically indicates excessive hydraulic pressure originating from saturated soil, water infiltration as well as improper grade. These types of cracks can occur both in poured cement foundations or block foundation walls and are often a sign of structural weakness. If left unaddressed these cracks could eventually lead to foundation wall Bowing, movement, additional cracking and possible foundation failure if left for long period of time.
Vertical cracking as a rule of thumb is usually less severe and is often caused by expected settlement and shrinkage of the foundation or slab floor. These cracks occur also in new homes as the foundation cures and dries and contracts. While most vertical cracks are benign, they should still be monitored for any widening or water entry. This could indicate an underlying problem such as hydrostatic pressure or poor soil conditions.
Diagonal cracks can be caused by differential settlement. Differential settlement for example is when a portion of the foundation settles at a faster rate than the other portion of the structure. Differential settlement causes a foundation to sink in one are more than the other. These cracks typically occur at the corners of the foundation walls. Cracking such as this can be problematic and get worse over time.
Stairstep cracking can typically be found in brick or concrete block walls. These types of cracks generally follow the mortar joints in a stairstep type pattern. The mortar joint is the weakest portion of the wall and that is why generally speaking it the mortar joints are the first places to experience this type of cracking because they are weaker than the underlying material. These stairstep cracks can be an indication of foundation movement which could be caused by soil shifting, water collection close to the foundation walls or even foundation heaving or settlement. Large stairstep cracks that are wide can be concerning and typically they call for evaluation from a professional engineer.
Hairline type cracks or in a generally superficial that typically result from the shrinkage of concrete or wall materials. These thin hairline type cracks are generally not a structural problem. However if found in a basement wall or floor slab they can allow moisture intrusion in.
Several factors contribute to the development of these types of cracks in a home’s structure.
Foundation settlement:
All homes settle over time. Excessive or differential settlement can cause significant cracking, and this occurs when different parts of the foundation settle at different rate and this is usually caused by varying soil conditions, inadequate soil compaction, and water laying too close to the foundation wall possibly caused by misplaced downspouts or poor exterior water controls.
Expansive soil:
Soils with high clay content absorb water and expand. This type of soil can also shrink when it’s dry creating soil movement that puts stress on the foundation wall of a home. Soil that expands and contracts can cause heaving or settlement leading to cracks in walls and flooring. This also includes cracks in foundation walls and cement floor slabs.
Hydrostatic pressure:
One of the major culprits and causes of foundation wall cracking and structural failure is hydrostatic pressure. Hydrostatic or hydraulic pressure builds up when the soil surrounding the foundation become saturated. This water has nowhere to go or to drain. The water collection begins pushing force against the foundation walls. Both concrete and masonry block foundations are strong when they are pushed on from up to down. However, they are weak in tension meaning they can easily resist vertical loads pushing against them but have difficulty against lateral loads pushing from the outside inward. When this hydrostatic pressure becomes too great and exceeds the walls capacity to push against it the walls will crack and even bow in overtime.
How hydrostatic pressure creates cracking
Hydrostatic pressure can create various types of cracking such as horizontal cracks which are the most common result of excessive water pressure. These cracks generally appear mid wall height and can be seen in the basement and can get worse over time. The issue that we have as NJ home inspectors is that there are many basements that are completely finished and we as home inspectors cannot visibly see the foundation walls because they are covered with interior finishes. This is a limitation when assessing the condition of foundation walls in homes.
Hydrostatic pressure can also create water seepage. Water can enter this type of cracking and allow water to infiltrate the basement or crawl space leading to basement water infiltration, possible flooding and creating conditions that are conducive to mold growth
Efflorescence:
Efflorescence is a powdery white mineral substance left behind on foundation walls during prolonged moisture exposure. Efflorescence can be mistaken for mold however efflorescence is white in color because it contains significant amounts of calcium.
How to mitigate hydrostatic pressure
The number one thing that you can do to alleviate the possibility of buildup of hydraulic pressure is to ensure that gutters and downspouts direct water at least 5 feet away from the exterior foundation wall and that there is a positive grade around the entire perimeter of the home that will direct water away from the foundation walls rather than allow water to collect close to them.
Installing a sump pump or perimeter basement drain system can also help relieve this hydraulic pressure by allowing it to have an outlet or in this case inlet so water pushes through openings in the foundation wall then this water enters into a perforated pipe system and that water then is directed to a sump pump which then pipes this water out from the home.
However, the most important aspect of relieving this pressure is to control water around the outside of the home so it does not collect close to the home. This is the number one thing.
Why foundations crack:
Foundations are especially vulnerable to cracking and movement due to their constant exposure to soil pressure and the forces of soil settlement.
Shrinkage cracks- When concrete dries or cures it shrinks slightly, and this can lead to small hairline cracks that are typically not structural.
Heaving and settling- Excess moisture or soils that are expanding can cause the foundation to shift or move leading to diagonal type stairstep or horizontal cracking.
Load distribution issues- If the foundation is not designed to handle the weight of the structure above it, stress cracking can form over time
Improper drainage- Water collecting around the exterior foundation walls weakens its integrity and increases the likelihood of cracking due to the force of water pressure.
External forces- The weight of patio and driveways or other exterior typically masonry components can exert more stress on the foundation wall than it is designed to withstand. This can cause cracking in some instances.
Basic overview of repairing cracking:
Hairline cracks can be repaired with epoxy or waterproofing sealant to prevent water infiltration.
Vertical or diagonal cracks, if they are minor, they can be sealed but if they are wide foundation specialist should be boarding to inspect them and design an appropriate repair
Stairstep type cracks depending on severity may require foundation peers or specific structural bracing
Preventative measures:
To minimize cracking some measures that can be taken are to ensure the proper grading and drainage around the house exists as well as discharging water from the downspouts away from the foundation walls. You can attempt to maintain consistent soil moisture levels around your home. You can avoid planting large trees and keep patios a distance from the house.
Cracks in homes can range from typical cosmetic cracks to more significant structural cracks. New Jersey home inspectors should understand how cracks form in homes and should be able to determine their severity. Homeowners should regularly inspect their homes for cracking and document any changes and hire professional help when the cracking is more pronounced. Addressing any potential issues early can help prevent costly corrections down the road and ensure the stability of the homes structure. If you have any doubt about cracking found in your home, hire a structural engineer or foundation repair specialist to determine if any corrective actions are necessary.