How To Seal Basement Door [Including Bulkhead Doors]

A basement door can only provide optimal protection and security if it has proper sealing. Gaps and other imperfections can cause problems like water leaks and pests to enter the subterranean space. By now you’re wondering, how can you seal your basement door properly? We researched for you and asked industry experts to give you this answer.

The process to seal basement doorways like bulkhead doors might be based on the location of the problems:

  • Apply an epoxy injection system for sealing hairline crack areas on the nearby foundation.
  • Use a rubber sealant to close concerns like gaps and holes on the cellar door.

It might seem like a relatively straightforward job to seal basement doors. But miss a few details and the project can have disastrous results. Keep reading as we tackle the details of sealing cellar doors.

An iron door to the basement, How To Seal Basement Door [Including Bulkhead Doors]

How Do You Seal A Basement Door?

Although basement doors come in different shapes and sizes, many models follow similar sealing methods. However, some variants, such as the ClamDoor clamshell basement door, may already have a pre-existing seal upon purchase. It’s a good idea to check if your basement’s door has a seal to prevent unnecessary purchases.

But if your cellar door doesn’t possess a built-in seal, the first step is to find the causes of concern on and around the doorway. Once found, the next steps depend on the location of the issue:

Open storm cellar door

Cracks in the Foundation

If you see hairline cracks in the foundation near the basement door, you can fix these issues with an epoxy injection system. This product can help seal cracks that are about 1/16 to 1/8-inch wide. Once you apply the substance into the small gaps, your next steps are:

  1. Spread the sealant using a putty knife.
  2. Wait for the product to cure, which may take about 72 hours.
  3. Once cured, use a caulking gun to squeeze the product into the cracks’ depths.
  4. Let the product cure for roughly the same amount of time as before.
  5. Once it dries, use a saw to trim the protruding areas.

Check out this epoxy injection kit on Amazon.

Holes in the Door

Many basement doors generally have metal constructions. If you have a cellar door using that material, follow the steps below to fix small- to medium-sized holes:

  1. Use coarse-grit sandpaper (e.g., 100-grit) to help flatten and level the area around the hole.
  2. Clean the resulting dust around the holes using a brush or vacuum cleaner.
  3. Apply rust remover to any lightly corroded areas.
  4. Mix your preferred metal bonding sealant with a compatible hardener. Make sure to follow the products’ instructions that should be on the label.
  5. Spread the sealant on the hole using a putty knife or other similar flat-headed tool.
  6. Let the filler dry before sanding the area with another course-grit sandpaper.
  7. Use lighter-grit sandpaper to buff out kinks that might appear.
  8. Clean the area with a cloth or rag.

Check out this sealant for metal on Amazon.

Additional Pieces of Information

You may need to contact a specialized technician if the faults are extensive. For example, some bulkhead doors mainly have metal construction, which may corrode or rust over time. Attempting to save these materials without proper knowledge may cause more harm to the door than intended.

Another option is to purchase a cellar door with built-in weather-resisting features. The extra aspects might increase the price of the entryway. But investing in these additional options may provide long-term convenience and peace of mind.

Check out this weathertight basement door on Amazon.

How Do You Prevent Water From Coming Into Your Basement Door?

Hatch trap door for cellar basement storage

You can choose among different products to seal your basement door and reduce the risks of water damage. One option is to use weather stripping.

Take note that weather strips are ideal for keeping rain and snow outside the premises. These products are usable on different doorways, including cellar doors. Choose from different weatherstripping variants on the market, such as:

  • Strengthened felt: Touted as one of the most common types of weather stripping, reinforced models often use materials like cotton and wool. These components are often reasonably inexpensive, making this conventional weather-resisting option ideal for tight budgets.
  • Metal: Weather strips made from this material are usually more expensive than most traditional options. However, metal can generally last for decades, which makes it ideal for long-term use.
  • Plastic: Also called V-strips or tension seals, these strips often have built-in adhesives for fairly convenient installations.
  • Ethylene propylene diene monomer (EPDM) rubber: Commonly used in roofing, this material can lend its weather sealing properties to doors. It’s a gasket that can provide extra heat and sound insulation to homes.
  • Vinyl: Vinyl weather strips may last for at least 5 years. This component might also help improve energy efficiency, leading to lower electricity bills.

Check out this vinyl weather strip on Amazon.

How Do You Mouse-Proof A Bulkhead Door?

The way to tackle mice problems that go through a cellar door is to seal the gaps that are in and around the immediate area. Take note that mice can enter through a bulkhead basement door, which can lead to infestations if left unchecked. One of the reasons is because of a porous bulkhead installation, providing access to the pests.

Before proceeding with the sealing, you should check the areas of concern. Start by closing the bulkhead door from the inside. Make sure to turn lighting fixtures off to see the locations where natural light passes through the doorway. These gaps are going to be the offending areas.

Once you know those places, you can proceed to seal those locations. One way to seal them is by installing a weatherstripping kit. Here are the steps to accomplish this task:

  1. Start by placing the U-shaped weatherstrip on the header flange. Make sure that the feeding is as secure as possible to prevent unnecessary movement.
  2. Cut the excess weatherstrip material with a pair of tin snips.
  3. Move to the vertical side panel flanges and install more of the U-shaped weatherstripping to those areas.
  4. Then, move the center side panel and apply the U-shaped weatherstrip material to that location.
  5. Apply the bulb trim gasket on the bottom flanges to the two door leafs. Again, trim the excess material with the tin snips.
  6. Install the rubber seals at the top and bottom of the door leaf caps.

Additionally, watch the video below to see the steps mentioned above in action:

You can also watch the video below if you’re having trouble looking for the places to work on your bulkhead door:

Check out this product on Amazon.

Should You Close Your Basement Door In Winter?

Cellar stairway in a New York City Street with metal doors

Leaving the basement door open during the winter may invite problems to the adjacent space. For instance, an unfinished basement may cause concrete floors and walls to expand.

Wall insulation and carpet flooring may help mitigate the potential issues caused by winter weather in the basement. But one relatively inexpensive solution to prevent these issues is to keep the basement door closed.

Read this post to know more about the importance of keeping basement doors closed: "Should A Basement Door Be Opened Or Closed In The Summer?"

Are Bilco Doors Insulated?

Certain Bilco doors don’t have insulation. But the entryway that this particular cellar door leads to might have standard batt fiberglass insulation.

On the other hand, Bilco offers basement doors with water-resisting features. Homeowners that acquired other Bilco door models may still enhance the doorways’ insulating capabilities by applying certain DIY techniques.

Check out this Bilco basement door on Amazon.

Does Flex Seal Work For Waterproofing?

Flex Seal is used to waterproof different spaces, including your basement. You can use products like the Flex Shot and Flex Seal Liquid MAX for that purpose.

Use these products by following these steps:

  1. Apply Flex Shot on small gaps and holes. Then, let it cure.
  2. Use a paintbrush or roller dipped in the Flex Seal Liquid Max to cover cracks, crevices, and pinholes.

Watch the quick video below to see how to use these Flex Seal products to waterproof a basement:

Keep in mind that covering gaps and seals with Flex Seal is only one way to waterproof a basement. You can also install the correct flooring material to ensure the subterranean space doesn't contract significant water damage. Read this post to learn more about that topic: "What Is The Best Flooring For A Basement Bathroom?"

Check out this product on Amazon.

Final Words

The way to seal basement doors often depends on the offending locations. You should also use the appropriate tools for the job. Although you can use DIY techniques to fix these concerns, think about hiring professionals if the repair projects seem to be out of your current skillset.

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