Have you noticed a crack in your foundation? The first step to fixing a foundation crack is identifying the type of crack. Here are the 8 most common types.
1. Hairline or Shrinkage Cracks
Hairline or shrinkage cracks are common in new poured foundation constructions. They usually appear within the first year and occur when the foundation begins to dry out and lose moisture. The good news is that these cracks are usually cosmetic and can be fixed by DIY homeowners for little cost.
2. Vertical Cracks
Vertical cracks in your foundation wall are less serious than horizontal cracks and do not pose a structural threat. They are commonly found in poured foundations and run straight from the top to the bottom of the wall. Vertical cracks are one of the most common types of cracks in basements. They are caused by the foundation settling over time or the natural curing process of concrete.
If there’s no moisture and you can’t fit a quarter into the crack, there’s no immediate threat. You can take photos and monitor the crack or repair it with an epoxy injection.
3. Horizontal Cracks
Horizontal cracks in your basement foundation are serious. They’re found below ground level where the frost line is and are often caused by the freeze-thaw cycle. This type of crack is often due to uneven soil and hydrostatic pressure from water pushing against your foundation wall. You might notice the foundation bowing inward and water leaking into your basement. Both poured and block foundations can develop horizontal cracks.
4. Diagonal Cracks
Like vertical cracks, most diagonal cracks in foundations do not pose a serious threat to your foundation’s structural integrity. They appear at a maximum 30-degree angle from the vertical and are caused by the natural curing of the concrete foundation wall or settling over time.
When you spot a diagonal crack, take a photo and note the date. Check again in six months; if the crack continues to grow, call Bisson Expert for advice.
5. Stair-Step Cracks
Block foundations are prone to stair-step cracks. You might also see them in brick walls above poured foundation walls. These types of cracks occur along the mortar joints and pose a serious threat to your basement foundation’s integrity. There are two common causes of stair-step cracks: Foundation settling or moisture issues outside your foundation.
If you can fit a quarter into the foundation crack, call us for a professional inspection and repair options. While some fine cracks in the mortar are common, any larger crack represents a threat.
6. Foundation Slab Cracks
Poured concrete slabs are prone to developing cracks over time. The challenge is understanding why the foundation slab crack occurred. There are four common reasons:
- Concrete Curing: The most common reason is the natural drying, settling, and curing of the concrete slab. This doesn’t pose a structural threat and is mainly cosmetic.
- Slab Settling: If a new foundation slab develops settling problems, you’re in trouble. This can be caused by poor compaction or poor soil conditions.
- Frost Heaving: Crawlspace foundation slabs that are at ground level or above are at risk of frost heaving. In freezing weather, water under the slab can freeze, causing the concrete to heave.
- Presence of Pyrite: Pyrite is a mineral that, when in contact with oxygen, expands and can cause concrete slabs to crack. These cracks are often accompanied by white powder. To learn more about this, please refer to this page.
7. Non-Structural Crack
A non-structural crack in the foundation is a crack that doesn’t pose a threat to the structure of the house and usually only causes leaks during rainstorms or when snow melts. Despite the lack of structural threat, water seeping into your basement is always a serious matter that needs attention.
Water seeping into your home can damage your belongings, walls, floors, and contribute to mold growth. If left untreated, these types of cracks can also worsen over time.
8. Structural Crack
These types of cracks are extremely serious because they pose a risk to the structural integrity of your home. An obvious sign of structural deficiency is horizontal cracks and cracks wider than a quarter of an inch. Structural foundation cracks are usually the result of movement, whether caused by temperature changes, soil pressure, or soil shrinkage.
In this case, there’s likely a bigger reason for the cracks. A foundation expert should assess the symptoms and determine the best solution to address the structural dangers.
