How to Waterproof the Basement? Interior, Exterior and Drainage

Written By Adam Paul - Waterproofing Expert

The basement should be waterproof in order to protect it from the seeped and leaked water inside the basement. When you waterproof the basement, you should have proper tools and recommended products to have a durable waterproofing membrane.

Basement waterproofing is a combination process of Interior basement wall and floor waterproofing, exterior Basement Wall Waterproofing, and Building Interior and Exterior Basement Drainage System.

The interior basement wall and floor waterproofing is installing an impervious layer in the inside of the basement wall and floor to prevent the waterproofing inside the basement. Exterior basement wall waterproofing is installing a waterproofing membrane outside the basement wall in order to prevent water from entering the basement. Building an interior and exterior drainage system is essential to contrall the seeped water in the basement. Each of these processes has specific steps, methods, products and guidelines you should follow.

You can protect the waterproofed basement by doing regular inspections and maintenance, keeping gutters and downspouts clean, installing window well covers, doing regular maintenance, insulating the water pipes, and Avoiding overwatering the garden. Damproofing the foundation is essential for increasing the basement water protection of a building.

How to Waterproof the Basement?

The basement waterproofing is a combination process of interior basement wall and floor waterproofing, exterior basement wall waterproofing, building interior and exterior drainage system and basement door, window and sprawl space waterproofing. You should waterproof all the above parts of the basement for a completely sealed basement.

How to Waterproof Interior Basement Walls and Floors?

The interior basement wall and floor waterproofing is installing an impervious layer in the inside of the basement wall and floor to prevent the waterproofing inside the basement. Interior basement sealing is the most popular way to stop the water leaking from the basement walls and floor. You should follow the below steps to waterproof the interior leaky basement. 

1. Identify the water-related problem inside the basement

The first step of interior basement waterproofing is to identify the source of the water problem. Check if there any cracks and holes in the basement walls and floor and mark the seeping areas in the basement. You can do this during the rainy season.

2. Clean inside the basement floor and walls

Once you have identified the problem areas on the basement floor and wall, you should clean them thoroughly. If the water leakage is high, you have to stay until the dry season to clean the surface. You should remove any dirt, debris, or loose concrete on the surface when you clean the basement interior. Because waterproof sealants can adhere tightly to the cleaned surface. 

3. Repair cracks Inside the basement floor and walls.

If there are cracks on the basement floor and walls, they must be repaired before applying the waterproofing membrane in the basement. You can use concrete patch products to fill in the cracks. The purpose of this step is to prevent water from seeping through the cracks. 

• Tools and Materials for basement crack repairing: Putty Knife, Concrete Patch Product
• Recommended Products for basement: Dap 37584 Liquid Cement Crack Filler, Quikrete Concrete Crack Seal

4. Apply waterproofing product on the Interior basement floor and walls

After crack repairs, you can start sealing the basement floor and walls by using a suitable waterproofing product. Waterproofing products are available as sealant, coating or paint.

You should follow the manufacturer's instructions and guidelines when you apply the product. After applying the waterproofing membrane, you should keep it for curing. Do not check it for water until it completely dry. 

• Tools and Materials: Waterproofing product, Paint roller, Paintbrush
• Recommended Products: Drylok Waterproofer, RadonSeal Plus Deep-Penetrating Concrete Sealer

5. Install a sump pump in the basement below the floor level

If your basement is tend to heavy water leaking, you should build a durian system along the perimeter of the basement. The drainage system can accumulate the seeped interior basement water in the sump well. The sump pump can pump out the accumulated water in the sump well.

• Tools and Materials: Sump pump, PVC pipes, Check valve, Gravel
• Recommended Products: WAYNE CDU980E Submersible Sump Pump, Zoeller M53 Mighty-mate Submersible Sump Pump

6. Install a Dehumidifier in the basement.

After sump pump is installed, you should control the humidity in the basement because humidity inside the basement can cause to build mold and mildew. Using a dehumidifier, you can reduce the basement interior humidity and prevent the mold growth. You can keep the basement inside always dry condition after this installation.

• Tools and Materials: Dehumidifier
• Recommended Products: hOmeLabs 4,500 Sq. Ft Energy Star Dehumidifier, Vremi 50 Pint 4,500 Sq. Ft. Dehumidifier

How to Waterproof Exterior Basement Walls?

Exterior basement wall waterproofing is installing a waterproofing membrane outside the basement wall in order to prevent water from entering the basement. Exterior basement wall waterproofing is more effective than interior waterproofing systems. You can do exterior basement waterproofing on old and new basements. You should follow the below steps to seal your basement properly.

1. Excavate the basement outside up to the basement floor level - You should excavate the exterior of the basement up to the basement floor outside.
2. Inspect basement exterior and interior damages - When the basement exterior walls are excavated, you can clearly see the cracks and damages on the basement wall that can cause water to seep inside the basement.
3. Repair cracks on the basement wall - After inspecting the process, you should repair cracks on the basement wall. You can do both interior crack repair and exterior crack repair by using waterproof sealants. 
4. Install Exterior waterproofing membrane - After the crack repair process, you can install an exterior waterproofing membrane on the basement walls. You can use sheet membranes such as bituminous, EPDM, or HDPE as the exterior waterproofing membranes. And manufacturer recommended waterproof sealant, coating or paint on the exterior basement walls.
5. Install Exterior Drainage System: After exterior waterproofing is done, you should install an exterior drainage system without damaging the basement waterproofing membrane. Exterior basement drainage system is installed at the base of the wall to carry water away from the foundation. This system usually includes a perforated drain pipe covered with gravel. 
6. Backfill the exterior basement using the excavated - After exterior waterproofing is done and the water channel is built you should backfill the basement outside using the excavated soil. 

How to Install Basement Interior and Exterior Drainage System?

Building an interior and exterior drainage system is essential to contrall the seeped water in the basement. The interior drainage system is essential for the interior basement waterproofing. But exterior drainage system is more important in highr basement walls because higher basement walls crate higher water table. 

Installation steps for Interior drainage system

1. Identify the heavy water-seeped areas inside the basement: First, identify where water is seeping into the interior of the basement. This could be anywhere from the basement to the walls or the roof.
2. Install Interior Footing Drains - This involves cutting a channel around the perimeter of the basement floor, laying down the perforated drain pipe, and covering it with gravel. The drain pipe should be sloped towards the sump pump pit.
3. Install a Sump Pump in the basement below the floor level - The sump pump will pump the water out from the pit and away from the building. Make sure to choose a pump that's the right size for your basement area and accumulated water volume.
4. Seal the basement wall interior cracks - After the sump pump is installed in the basement, you should use a waterproof sealant to seal any cracks or holes in the walls where water might be getting in.
5. Fix and finish the basement floor - Once the drainage system is installed, you can pour new concrete over the floor to cover the system.

Installation steps for exterior drainage system

1. Excavate Around the outside of the basement up to the basement floor.
2. Inspect and Repair the exterior basement Walls
3. Apply a Waterproof Membrane on the exterior basement walls.
4. Install a French Drain around the exterior basement wall parameter 
5. Backfill exterior basement Trench using excavated soil
6. Restor the landscaping. 

What Tools and Materials are Needed for Basement Waterproofing?

When you waterproof the basement, you will need suitable tools and recommended products. Tools are essential for surface preparation and applying the waterproof layer. Waterproof materials are used to create a waterproof layer on the substrate. Hence you should use below tools and materials for your basement waterproofing project.

Essential tools for basement waterproofing

1. PPE equipment - Use Gloves, glasses, and boots, as personal safety equipment.
2. Sump Pump and dehumidifier - Sump Pump is used to remove accumulated water in the basement from the sump well. A dehumidifier is used to control the humidity level in the basement.
3. Caulking Gun - A Caulking Gun is used to apply caulk for sealing joints and small cracks in the basement.
4. Utility Knife - Utility Knife is used to cut the vapour barrier or waterproofing membrane for the basement.
5. Hammer Drill and masonry drill bit - Use a hammer drill and masonry drill bit for drilling the basement when needed.
6. Trowel - Trowel is used to apply concrete mix or hydraulic cement in the basement.
7. Bucket - Bucket is used for cleaning the basement surface before waterproofing.
8. Sponge - Sponge is used for cleaning the basement surface before waterproofing.
9. Paint Roller, brushes and trowel - Used to apply waterproofing paint in the basement.

Essential materials for basement waterproofing

1. Waterproofing Paint - Waterproofing Paint is used to create a seal on the interior basement walls and floor.
2. Concrete Sealer - The concrete sealer is used to fill any cracks or holes in the basement's concrete.
3. French Drain - A French Drain is used to redirect water away from the basement.
4. Vapor Barrier - Vapor Barrier is used to prevent moisture from seeping into the basement.
5. Hydraulic Cement - Hydraulic Cement is used to repair large cracks or holes in the basement.
6. Waterproofing Membrane - Waterproofing Membrane is used to create a waterproof barrier on the exterior of the basement walls.
7. Insulation - Insulation is used to help regulate the temperature in the basement and reduce condensation.
8. Caulk - Caulk is used to seal joints and small cracks in the basement.

How to Protect Basement Waterproofing?

You can protect basement waterproofing by doing regular inspections and maintenance, keeping gutters and downspouts clean, installing window well covers, doing regular maintenance, insulating the water pipes, and Avoiding overwatering the garden.

1. Do regular maintenance on basement waterproofing - Check your basement regularly for signs of water damage, such as damp spots or mold. If you find any, address them immediately to prevent further damage.
2. Keep gutters and downspouts clean around the basement - Clogged gutters can cause water to overflow and accumulate around your foundation, which can damage your waterproofing. Ensure your gutters and downspouts are clean and directing water away from your house.
3. Install window well covers to prevent rainwater accumulation to the basement - If your basement has windows, install window well covers to prevent rainwater from accumulating in the wells and potentially leaking into your basement.
4. Regularly check and maintain your sump pump in the basement - If you have a sump pump, make sure it's in good working order. Test it regularly, especially before periods of heavy rain.
5. Control interior basement humidity - Use dehumidifiers and/or air conditioners to maintain less humidity.
6. Regularly check and repair the exterior basement - Cracks and damage to the exterior foundation can lead to water seeping into your basement. Regular inspections and prompt repairs can help protect your basement waterproofing.
7. Avoid overwatering your garden - Overwatering plants located near the foundation of your home can result in water seeping into your basement.

Should You Waterproof the Foundation?

Yes, you should damp-proof the foundation to protect your home from moisture damage. A waterproof foundation can prevent water from seeping into your basement and causing problems like mold, mildew, and structural damage. You can waterproof the foundation using these 8 step guide to reduce cost and time.