All About Foundation Cracks: Causes, Types, Repairing and Preventions
Foundation cracks are breaks or crashes that occur on the foundation walls or floors. Foundation floor cracks are the breaks and crashes in the basement floor and the foundation's concrete slab, while foundation wall cracks are the breaks and crashes in the foundation's walls.
Foundation cracks are different in size according to their width and shape. The minimum width of the foundation crack is 1/8 inch (3 mm). The 9 main types of foundation cracks are horizontal cracks, stair steps, hairlines, vertical, diagonal, shrinkage, foundation slab, non-structural foundation crack, wen non structural foundation cracks and structural foundation cracks.
Foundations are cracked due to water damage in the foundation, soil expansions, structure setting, poor foundation construction, and temperature fluctuations. A cracked foundation can be repaired by crack sealing and crack injection methods. You can use epoxy, caulk, concrete crack sealer, polyurethane, and Sikaflex for foundation crack sealing.
If you do not seal the cracks in the foundation, water can leak into the basement and it will cause to basement flooding, health problems can arise due to mold and mildew growth, basement maintenance costs can be increased, increase pest infestation, decrease property value and reduce the structural stability over time.
You can prevent foundation cracks by hydrating the foundation, installing the French drain system, avoiding planting trees near the foundation, cleaning the downspouts and gutters, and maintain proper grading on the land.
You can prevent cracked foundation water damage by waterproofing the foundation, maintaining the proper humidity level, installing a proper drainage system, maintaining gutters and downspouts and repairing plumbing leaks near the foundation.
What is a Foundation Crack?
A foundation crack is a break or crash in the foundation walls or foundation floor. Foundation cracks are different in size according to their width and shape. The minimum width of foundation crack is 1/8 inch (3 mm). The shapes of the foundation cracks can be diagonal, stair-shaped, straight, or a combination of the above shapes.
The 5 main types of foundation cracks are hairline, vertical, diagonal, stair-step, and horizontal foundation cracks. The four main reasons for foundation cracks are improper construction techniques, excessive water pressure, nearby tree roots, and changes in the soil beneath the foundation, such as droughts and soil erosion. Foundation cracks cause disadvantages such as water damage, rusting of lintels, issues in the roof frame, and issues in the footings and concrete pads.
What Causes Foundation Cracks?
Foundation crack can occur due to these 5 reasons such as water damage in the foundation, expansive soil, building structure setting, poor foundation construction, and temperature fluctuations in the environment. These reasons cause to crack foundations in different sizes.
1. Water Damage In the Foundation
Foundation cracks occurs due to water damage in the foundation. The undrained water can be collected near the foundation due to rainstorms, melting snow, broken water lines, and landscaping. The collected water can exert hydrostatic pressure against the foundation, causing cracks. Water damage can create horizontal foundation cracks.
2. Expansive Soils Near the Foundation
Foundations can be cracked horizontally due to the expansion of soil near the foundation. The soil will be expanded and contract due to changes in the moisture level. Then, the soil will swell and uplift the foundation, causing cracks.
3. Building Structure Settling.
Building structure cause the foundation to crack vertically. When a building settles, it will slightly shift into the ground. This will distribute the weight of the building and the pressure unevenly on the foundation, causing cracks.
4. Poor Foundation Construction.
Poor foundation construction cause to crack the bottom vertically. This can happen when the foundation is constructed poorly using low-quality materials and needs reinforcement, such as rebar and mesh.
5. Temperature Fluctuation.
Foundation can crack due to thermal expansions and contractions due to changes of temperature in the environment. Prolonged sudden temperature fluctuations cause to crack, weak, and deteriorate the foundation material and tend to leak the water during the rain or snow melting season.
Related: What to Know About Foundation Waterproofing?
What are the 10 Types of Foundation Cracks?
The most occur 10 types of foundation cracks are horizontal cracks, stair steps, hairlines, vertical, diagonal, shrinkage, foundation slab, non-structural foundation crack, wen non structural foundation cracks and structural foundation cracks.
1. Horizontal Cracks
Horizontal foundation cracks have a width between 1/6 to 1/8 inches. These are mostly appearing in the frost line. This can mainly occur due to unbalanced soil and hydrostatic pressure. Horizontal cracks can weaken the foundation's integrity and cause water intrusion.
2. Stair Step Cracks
Stair step foundation crack has a width of 1/8 inche. Stair step cracks are visible in mortar joints in the foundation. Variations in soil moisture level, improper drainage system, and soil roots are are main 3 reasons for the stair-step cracks. These cracks can cause moisture problems outside the foundation and sink in one area and foundation settlement.
3. Hairline Cracks
Hairline foundation cracks consits of 0.08 mm of width. These cracks appear in mortar joints in bricks and concrete blocks. Temperature and humidity fluctuation are the main reasons for these cracks. Hairline cracks can cause water seepage into the basement and dampen the foundation, increasing the mold growth.
4. Vertical Cracks.
Vertical foundation cracks have a minimum width of 3mm. Vertical cracks are primarily visible in poured foundations running straight up and down the wall. These cracks are mainly caused by settling the foundation and result from the natural concrete curing process. Vertical cracks can make the foundation unstable and increase moisture levels, causing mold growth.
5. Diagonal Cracks
The diagonal foundation cracks are 1/4 inch of width. Diagonal cracks are visible in corners of doors and windows, junctions, and load-bearing walls. The main reason for diagonal cracks is the insufficient number of vertical expansions along the length of the wall. Due to diagonal cracks, water infiltration and structural integrity reduction can occur.
6. Shrinkage Cracks
Shrinkage foundation cracks have a width of 2 mm. Shrinkage cracks are found in vast surfaces such as flat concrete surfaces and concrete slabs. The main reasons for shrinkage cracks are dryness and loose moisture in the foundation. Shrinkage cracks can reduce the property value and increase water infiltration and safety hazards.
7. Foundation Slab Cracks
The foundation slab crack consists of 1/8 inch of width. Slab cracks are mostly found on basement walls. The three main reasons for slab cracks are natural drying, settling and curing the concrete slab, slab settlement, and frost heave. Foundation slab cracks can reduce the structural integrity, increase the growth of pests, and increase moisture issues.
8. Non-Structural Foundation Cracks
The non-structural foundation cracks is less than 3mm. Non-structural cracks are often found at window and door openings, drywall, and expansion joints and corners of the building. Non-structural cracks can occur due to lateral pressure exerted by the soil and as a result of the concrete curing process. These cracks can affect the integrity and stability of the foundation and mold growth.
9. Wet-Non Structural Foundation Cracks.
The wet non-structural foundation cracks are 1/8 inch in width. These cracks can occur as a result of the natural setting of the concrete and the evaporation of water from the concrete. These cracks are more visible in places with high moisture levels, such as basement walls, crawl spaces, and plumbing lines. Water seepage and the growth of mold and mildew are the key disadvantages of these cracks.
10. Structural Foundation Cracks.
Structural foundation cracks are more expansive than 1/4 inch. These cracks occur due to temperature fluctuations, soil pressure, and soil shrinkage. Structural cracks are mostly seen on basement floors, foundation walls, joints, and crawl spaces. Structural cracks cause severe damage to the structural integrity and reduce the property value.
What are Foundation Floor Crack?
Foundation floor cracks are the breaks and crashes in the basement floor and the foundation's concrete slab. Foundation floor cracks can be divided into structural and non-structural cracks. Some examples of foundation floor cracks are Hairline, vertical, diagonal, and horizontal cracks.
In the beginning, small floor cracks can occur due to changes in temperature and the settling of the building. These cracks can widen with time due to hydrostatic pressure and movement of soil, causing huge cracks. Foundation floor cracks can damage the structural integrity, damages to plumbing and electrical lines, uneven floors, and water seepage into the basement.
What are the Foundation Wall Cracks?
Foundation wall cracks are the breaks and crashes in the foundation's walls. Foundation wall cracks can be divided into two parts such as structural and non-structural. Examples of foundation wall cracks are horizontal, vertical, diagonal, and stair-step. In the early stages, small wall cracks can occur due to temperature fluctuation and the settling of the building.
With time, when the building settling process continues, these cracks can develop due to changes in the soil and hydrostatic pressure. The main negative impacts caused by foundation wall cracks are costly repairs, basement flooding, issues in safety, and reduced structural integrity.
How to Repair Foundation Cracks?
Foundation cracks can be repaired by 2 major methods.
- Foundation Crack Sealing
- Foundation Crack Injection
Foundation Crack Sealing
Foundation crack sealing is a process of repairing cracks in the foundation, restricting the entry of water and moisture through those cracks. Using foundation crack sealing, we can seal narrow cracks with a maximum width of 1/4 inch (6mm) and wide cracks with a maximum width of 1 inch (25mm).
Foundation crack sealing makes a barrier for entering water and moisture into the foundation, reducing water-related problems. Also, foundation crack sealing is a cost-effective remedy, and it stabilizes the foundation as well. Therefore, it is suitable for sealing foundation cracks.
Sealing cracks will prevent air and water leakages, spread of pests, and water seepage and give an ambient vibe to the foundation. When you seal the foundation crack, first clean the crack and remove any debris.
Then, evaluate the crack size and choose the appropriate sealing material for the evaluation. Apply the sealing material considering the manufacturer's guidelines while filling the crack. After the filling, remove the excess using a knife and smooth the finish. Allow it to be set.
The most common products used in foundation crack sealing are Epoxy injections, Polyurethane Foam, Hydraulic cement, Silicone sealants, polyurethane sealants, and crack repair kits.
Foundation Crack Injection
Foundation crack injection is sealing and waterproofing the cracks in the foundation's concrete. Foundation crack injection is more suitable for cracks with narrow widths. The maximum width that can be sealed by injection is ¼ inch (6mm).
Since crack injection creates a durable, long-lasting seal, provides structural reinforcement, and is a cost-effective repair method, it is more suitable for sealing cracks. Foundation crack injection prevents water and air leakage, reduces the instability of structures, minimizes the spread of pests, and protects the aesthetic nature of the foundation.
When you seal the crack by injecting,
- First, clean the crack and remove debris.
- Then, evaluate the size and width of the crack.
- Choose the injecting material according to the evaluation.
- Install the injecting ports inside the crack from 6- to 12-inch apart.
- Inject the sealing material using an injecting gun until the sealing material flows evenly and fills the crack. Allow it to be set.
When the material is set, remove injecting ports and excess injecting materials. The products that can be used for injection are Epoxy Resin, Polyurethane Resin, Acrylic Resin, Methyl Methacrylate Resin, and Sodium Silicate.
What Can Use to Repair Foundation Cracks?
These are the 5 materials you can use to repair foundation cracks
- Epoxy
- Caulk
- Concrete Crack Sealer
- Polyurethane
- Sikaflex
01) Epoxy
Epoxy materials penetrate deeply and create a durable seal, preventing water infiltrations. Also, epoxy materials have high thermal stability and can withstand a wide temperature range. Epoxy materials are resistant to prolonged exposure to water and moisture. Also, these materials are highly durable and absorb any external stresses and pressures.
02) Caulk
Caulk is a paste applied to cracks using a caulk gun. Caulk has adhesive solid properties and creates a long-lasting, strong seal. Also, caulk is resistant to temperature fluctuations and even water resistant. High-quality caulks are durable and resistant to UV Rays and environmental pollutants.
03) Concrete Crack Sealer
Concrete crack sealer is a liquid and can only be used for horizontal cracks. These are designed to withstand higher temperatures and can create a barrier to the moisture entrance. Since concrete crack sealers have strong adhesive properties, they can flow evenly and fill the crack. Also, these are highly durable against environmental changes and chemical damage.
04) Polyurethane
Polyurethane is a polymer used to seal cracks. It is thermally stable and resistant to water as well. It will create a robust and durable seal that prevents water infiltration and the entrance of moisture.
05) Sikaflex
Sikaflex is a polyurethane-based sealing material that is thermally stable and water resistant. It can create a waterproof barrier, seal cracks properly, and be used in cold weather conditions. Sikflex is durable and has strong adhesive properties, making the seal long-lasting.
What are the Negative Impacts of Foundation Cracks?
These are the 6 negative impacts of foundation cracks.
- Basement water leaking and flooding
- Health problems due to mold and mildew growths in the basement
- Basement maintenance cost is increasing
- Increase basement pest infestations
- Decrease the property value due to weak and damaged basement
- Reduce the structural stability over time.
Read More: Water Related Issues and Water Damage in the Houses
01) Basement Water Leaking and Flooding.
Through the foundation cracks, water can seep into the basement and accumulate. Most of the time, water seeps into the basement through horizontal and vertical cracks near the cellar. The accumulated water is a good breeding ground for pests and mold.
Also, it will create a damp environment and destroy the air quality inside the basement. Excessive moisture buildup can also reduce the basement's structural integrity and strength.
02) Health Problems Due to Mold and Mildew Growth in the Basement.
Hairline and stair-step cracks are the most common cracks that facilitate mold growth. These cracks will increase the water seepage along the walls, dampen them, and provide an ideal environment for mold growth.
Excessive mold exposure will cause respiratory issues, skin rashes, cough, eye irritation, and problems in the throat. Also, it will weaken the users' immune systems.
03) Increase Maintenance and Repair Costs of The Basement.
Every type of foundation crack should be repaired to avoid future issues. But horizontal and vertical cracks wider than ¼ inch will require a costly renovation. This will be an additional expense, and users will be under financial strain and stress.
Since some home insurance companies do not claim these expenses, it will be challenging for users. Also, renovation will be time-consuming and disruptive to daily routines.
04) Pest Infestation in the Basement Items.
Horizontal cracks and vertical cracks provide gateways for the pests into the basement. Pests like ants, mosquitoes, and cockroaches can destroy the basement items.
Also, it will damage the basement's structural integrity and property value. Mosquitoes and cockroaches can transmit diseases and cause health hazards as well.
05) Decrease the Property Value
Property value can be decreased by vertical, horizontal, and stair-step cracks. Value decreases property, which is hard to sell and will stress users.
Also, financial losses and low equity will destroy the mentality of the users. Also, value-decreased properties will destroy the aesthetic value of the basement.
06) Reduce the Structural Stability.
The most common foundation cracks that contribute to structural instability are stair steps and horizontal and wide vertical cracks.
Structural instability can cause movements in the foundation, damage to belongings, and water seepage. Also, it can cause safety hazards like shifting and collapsing of walls.
How to Prevent Foundation Cracks?
These are the 6 helpful ways to prevent foundation cracks
- Hydrate the foundation
- Install French drain
- Avoid planting trees near the foundation
- Clean downspouts and gutters
- Improve ground grading
01) Hydrate the Foundation
Dryness in the foundation can increase the cracks. Add water near the foundation area and moisten and hydrate the soil to avoid this. It will prevent soil from being expansive and exert stress on the foundation.
02) Install French Drain
A French drain with sump pump can direct the water away from the foundation and prevent it from soil being saturated and expanded. This helps to minimize foundation cracks, reducing the stress on the foundation.
03) Avoid Planting Trees Near the Foundation.
Plants can expand their roots around a large area, and these roots can make the soil expansive. If plants are too close to the foundation, the risk of foundation cracks increases.
04) Clean the Downspouts and Gutters.
Gutters and downspouts direct the rainwater away from the foundation. Cleaning them will prevent water from entering the foundation.
05) Proper Grading
The ground near your home should slope away at one inch per foot. The slope away from the house will prevent water accumulation near the foundation.
How to Prevent Cracked Foundation Water Damages?
You can prevent cracked foundation water damage by following below 5 succefull ways.
- Waterproofing the foundation
- Maintain the proper humidity level
- Install proper drainage system
- Install and maintain gutters and downspouts
- Repair plumbing leaks
01) Waterproofing the Foundation.
Waterproofing the foundation means creating a barrier in the exterior foundation walls to prevent water seepage and moisture entrance. This will minimize the hydrostatic pressure around the foundation.
02) Maintain Proper Humidity Levels.
Excessive humidity can condense and increase the moisture level. It helps to mold growth and health hazards.
03) Install Proper Drainage System.
Water should flow away from the house. French Drain systems are designed to divert water away from the home. We can reduce water damage by installing and properly maintaining the drainage system.
04) Install and Maintain Gutters and Downspouts.
Gutters and downspouts can direct water away from the foundation. Downspouts and gutters will prevent the accumulation of water near the foundation. Also, downspouts should be installed 5 - 10 feet away from the house to avoid water pooling.
05) Repair Plumbing Leaks
Repairing leaks in the plumbing and water supply lines helps prevent water accumulation inside the basement and mold growth.