Basement Waterproofing and Understanding the Causes of Flooding

Types of Basement Flooding

There are two main types of basement flooding:

Surface Water Flooding

Surface water flooding occurs when water accumulates around the exterior foundation walls and seeps into the basement through cracks or openings. This flooding often happens during heavy rainstorms or snow melts when large volumes of water run off the ground and pond around the foundation. Surface water can enter through window wells, cracks in the foundation, an undersized drainage system, or other openings.

Surface water flooding may be seasonal, mainly during rainy periods or snow melts. Or it can be a one-time event caused by a massive storm. This flooding often comes on quickly and may involve large volumes of water.

Groundwater Flooding

Groundwater flooding occurs when the water table rises and exerts pressure on the foundation walls, causing water to seep through cracks and pores in the concrete. A high water table can result from heavy rains, spring thawing, over-irrigation, or other factors.

Groundwater flooding is usually intermittent and happens as a slow seepage over time. The water often appears in multiple locations, resulting in wet walls or floors. This type of flooding may not be as dramatic as a surface water flood, but it can still cause substantial damage over time.

Causes of Surface Water Flooding

Surface water flooding occurs when water accumulates around the exterior perimeter of your home and seeps into the basement. There are a few common causes of surface water flooding to be aware of:

Poor Lot Grading or Drainage

Improper lot grading means the ground around your home slopes towards the foundation rather than away. This allows rainwater and snowmelt to collect around the basement walls and seep inside. A professional grading contractor can re-slope your yard to direct water away from the house.

Downspouts, gutters, and drainage pipes should also divert water at least 6 feet away from the foundation. Make sure these drainage systems are clear of debris. A French drain system can also help collect surface water and move it away from your basement.

Gutter and Downspout Issues

Clogged gutters allow water to overflow and spill down the side of your home. Gutter joint seals may also leak and dump water next to the foundation. Disconnected downspout extensions, crushed drainage pipes, or clogged downspout drains will also back up water.

Inspect and clean your gutters at least twice per year. Make any needed gutter repairs and extend downspouts to drain 6 feet away from the house. Downspout drains should be released into a municipal storm drain or a drywall.

Landscaping Problems

Having heavy clay soil, insufficient ground cover, or landscaping right up against the house can all increase the risk of surface water flooding.

Planting beds, lawns, and adequate ground cover help absorb rainwater. Avoid heavy clay soil or compacted soil immediately surrounding the foundation. Leave at least 12 inches between landscaping and the house.

Causes of Groundwater Flooding

Groundwater flooding occurs when water underneath the basement seeps in through cracks and openings. Common causes include:

• High Water Table – A high water table means the groundwater level is close to the surface. When the water table rises after heavy rains, it can force water through cracks in the basement floor and walls. Homes at the bottom of slopes or in low-lying areas are prone to a high water table.
• Broken Pipes or Sewer Lines—Cracked sanitary sewer pipes, broken water lines, or leaks in plumbing under or near the foundation can allow water to seep into the basement. Tree roots infiltrating sewer lines are a common cause of cracks and leaks.
• Cracks in Foundation – Small cracks or gaps in the foundation walls or floor provide an entry point for groundwater. Over time, cracks expand due to soil pressure, settlement, freeze/thaw cycles, and aging of the concrete or masonry. Groundwater will find the cracks and follow them into the basement.

Groundwater is persistent and can create a constant trickle or flow of water into the basement. Stopping groundwater flooding requires sealing foundation cracks from the exterior and interior. Dampproofing or waterproofing the foundation walls can also help prevent water seepage through cracks and pores in the concrete. Fixing leaks in underground pipes and improving lot grading can help reduce groundwater flooding risks.

Preventing Surface Water Flooding

Surface water flooding occurs when water builds up on the exterior of your home from sources like rain, melting snow, overflowing gutters, and malfunctioning appliances. Preventing this type of flooding requires managing water on the exterior of your home. Here are some tips:

Re-grade your property – Ensure the ground slopes away from your home’s foundation. This allows water to drain away from your basement walls. An adequate slope is 1⁄4 inch per foot for at least 10 feet. Extend grading as far away from the home as feasible. Re-grading can prevent thousands of gallons of water from collecting around your foundation.

Extend downspouts – Make sure downspouts extend at least 6 feet from your home’s foundation. Water dumped too close can pool and seep into basement walls and windows. Use downspout extensions to redirect water wells away from your foundation into drainage ditches or storm sewers.

Install perimeter drains – Perimeter drains are piping installed around the exterior of your foundation walls that catch surface water and divert it away from your home. They are typically buried 2-3 feet deep and surrounded by gravel. Perimeter drains discharge away from the home through a sump pump or by gravity. Installing them requires excavating around the foundation.

Preventing Groundwater Flooding

Groundwater flooding occurs when the water table rises above the level of your basement floor and walls. Since the source of water is under the ground, preventing this type of flooding requires keeping water from passing through the foundation and floors from underneath. There are a few key ways to prevent groundwater from flooding your basement:

• Waterproof the exterior of your foundation. Waterproofing paints, coatings, and sealants can be applied to the exterior foundation walls to prevent water from seeping through cracks and pores in the concrete. Professional waterproofing companies can also install drainage systems alongside the foundation footing to collect groundwater and direct it away from the house through underground pipes.
• Maintain your sump pump system. A properly functioning sump pump is critical for removing groundwater before it floods the basement. The sump pit, pump, discharge line, and battery backup should be regularly inspected and maintained to ensure the system operates when needed. The pump should be tested monthly by pouring water into the sump pit.
• Repair foundation cracks and leaks. Any cracks, holes, or leaks in the basement foundation or floors provide an entry point for groundwater. These defects should be sealed with hydraulic cement, epoxy injectors, or other appropriate sealants. In severe cases, major foundation repairs by a contractor may be required to waterproof the basement fully. Installing an interior drainage system or basement waterproofing membrane can also help direct seepage away from the living space.

Removing groundwater from basement walls and floors is the best way to avoid flooding damage. Contacting a professional waterproofing company to identify and remedy vulnerabilities can help provide long-term protection against groundwater flooding events. With the right prevention strategy, you can keep excess groundwater where it belongs–outside your basement.

Emergency Flood Control

Quick action is required to prevent or minimize damage when your basement is actively flooding. Here are some tips for emergency flood control:

Block Doorways

Use waterproof barriers like sandbags or polyethylene barriers to block doorways and prevent additional water from entering the basement. Focus on exterior doorways first, then interior doorways leading to unfinished basement areas. Seal as tightly as possible along the base of the doorway while allowing the door to open.

Use a Water Pump

For active flooding, use a sump or portable submersible pump to pump water out. Position the pump at the lowest point where water collects and run a discharge hose outside. Pumping too rapidly can damage your foundation, so pump out gradually if possible.

Soak Up Water

For minor flooding, soak up standing water using towels and mops. Remove wet items like carpets and furniture to prevent further damage. Use a wet/dry vacuum to suction up water. Dehumidifiers can help dry out damp areas.

Acting quickly to block, pump, and soak up floodwater can greatly reduce damage. But prevention is ideal – consider steps to waterproof your basement after the flooding stops.

Basement Flood Damage

A flooded basement can cause substantial damage beyond wet carpets and ruined boxes. Here are some of the significant effects basement flooding can have:

Ruined Possessions

• Flood waters may destroy anything stored in the basement, including furniture, keepsakes, appliances, and more. Even if items look salvageable, they are often unrepairable due to water damage and contamination.
• Important documents and paper items, such as photo albums, tax records, memorabilia, books, and more, will be ruined.
• Clothes, towels, rugs, and other textiles will likely be damaged beyond repair. Mud and contaminants in the flood waters can permanently stain fabrics.

Structural Issues

• To avoid mold growth, the drywall soaked by flood waters will need to be removed. This can mean re-drywalling entire rooms.
• Wood studs, sills, bottom plates, and other structural elements soaked by floods can warp, crack, or develop rot over time. This may require future structural repairs.
• Doors and windows can warp or become difficult to operate after water exposure. They may need replacement.
• Repeated soakings over time can cause cracks in concrete walls/floors.

Health Hazards

• Flood waters contain many hazardous contaminants, such as sewage, chemicals, bacteria, viruses, mold spores, and more. These can have negative health effects if people are exposed through direct contact or breathe in toxins during cleanup.
• Flooded areas will be breeding grounds for mold if not thoroughly dried out. Mold exposure can cause allergic reactions or illness.
• Rodents and insects can be attracted to damp, flooded areas, bringing disease.

Cleaning up from a flooded basement requires thorough drying, demolition, sanitizing, and reconstruction. If damage is extensive, professional mitigation services may be required. Flood waters can wreak havoc beyond just a bit of water on the floor.

Cleaning Up After a Flood

After a flood, cleaning up properly is critical to prevent mold growth and further damage. Here are some steps:

• Remove Excess Water – Use a pump or wet/dry vacuum to remove standing water. Mop floors and wipe walls. Absorb remaining moisture with towels.
• Dry out the Space—Open windows and doors and use fans to circulate air. Dehumidifiers can help remove moisture from the air. Don’t use heaters or ACs until all water is removed.
• Disinfect Surfaces—Scrub walls and floors with a disinfectant cleaner. Bleach solutions help kill mold and bacteria. Discard porous items such as carpeting or upholstery that can’t be thoroughly cleaned.
• Remove Damaged Materials—Inspect for water damage and remove damaged drywall, insulation, flooring, etc. If left wet, these provide food for mold.
• Monitor and Ventilate – Check for hidden moisture and drying progress. Continue using dehumidifiers and fans until fully dry. Proper ventilation prevents mold growth.

Thorough cleaning and drying are critical for preventing further water damage after a flood. Consider hiring a professional water damage company for large-scale flooding.

Hiring a Professional

Hiring professionals can help ensure your basement is adequately restored after a flood. Look for a company experienced in water damage restoration with expertise in the following services:

Water Extraction

Professionals use industrial sump pumps and dehumidifiers to remove standing water quickly. This helps prevent further structural damage and mold growth. Extraction equipment should remain in place until all moisture is gone.

Mold Remediation

If flood waters sit for more than 48 hours, mold growth is highly likely. Specialists use protective gear to remove moldy drywall, carpets, and other materials. A biocide may be applied to treat the remaining mold spores. Air movers and dehumidifiers help dry all surfaces completely.

Structural Repairs

A structural engineer can assess cracks, bulges, and shifting to determine necessary repairs. Damaged materials like drywall and insulation will need replacement. Floors may need leveling and anchoring. A waterproofing expert can help prevent future flooding through interior drainage systems, exterior landscaping, foundation seals, and sump pumps.

Hiring qualified professionals saves time and ensures proper flood damage mitigation. They have the right equipment, materials, and expertise. Be sure to verify licensing and insurance and check reviews. Flood damage can seem overwhelming, but the right restoration company will help you recover quickly.

Preventing Future Floods

Annual Maintenance

Regular maintenance of your home’s drainage system is one of the most effective ways to prevent future basement floods. Make sure downspouts are clear of debris and are directing water several feet away from the foundation. Inspect your sump pump and backup pump systems to ensure they are functioning correctly, and consider installing a battery backup if you don’t already have one. Replace the sump pump every five years or so. Checking traps and vents for blockages can also help prevent sewer backup floods.

Monitor Water Table

Pay attention to the water table level on your property during wet seasons. You may need to install a sump pump or interior perimeter drain if the water table rises close to the level of your basement floor. A professional waterproofing company can assess this and make recommendations. Monitoring wells on your property can also help you keep track of any changes.

Improve Landscaping

Making sure the ground around your home slopes away from the foundation is crucial for directing surface water away. Build up low areas with compacted soil and consider installing swales or French drains to help channel the water. Extend downspouts and sump pump discharge pipes well past the slope. Finally, avoid planting trees near the foundation, as roots can damage foundation walls and drainage pipes over time.

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