How to Seal a Bilco Door

Water seeping into a basement through a bilco door is a homeowner’s worst nightmare. 

Whether you are using it as an extra living space or for storage, this can wreak havoc on your belongings. And depending on the extent of water leakage, it may even start to undermine the integrity of your foundation. 

Thankfully, there are a few things you can do beforehand to ensure that this never happens. One of these is figuring out how to seal a bilco door. 

There are three sealing solutions we recommend: weatherstripping, investing in different types of bulkhead doors and using a concrete sealant. Read on to learn more.

Methods for sealing bilco doors


If you don’t want to find water leaking through the bulkhead door that leads to your basement, consider getting weatherstripping installed. 

What we like about this approach is that you’ll have the freedom to select from different types of weather stripping materials like:

  • Tubular rubber – this constitutes a narrow sponge rubber. While it’s the most expensive option, it’s also the most recommended for a basement door, rightly so. 

This is because it can be cut to different lengths so it fits your doors perfectly without leaving any gaps. Moreover, it provides the best durability compared to foam and felt alternatives. 

  • Felt – this type of weatherstripping is usually sold in rolls. There are two versions of this: a plain one and another that comes reinforced using a pliable metal strip. 

The advantage of this is that it’s incredibly cheap. However, this comes at the expense of durability. Chances are, you will likely have to replace it after just one or two years. 

  • Foam tape – this is right in the middle of the pack. It’s neither too expensive nor too cheap. And while it’s more durable than felt, it doesn’t provide the longevity you get from rubber. 

Bilco doors

If your basement door is damaged beyond repair, consider installing an entirely new entryway. Bilco has been in this space for a while, and it’s built a reputation for itself by producing premium-quality doors. Here’s a list of the main bilco doors available:

  • Classic series – these doors are meant to provide a safe entryway to a living space or storage area. They have ultra-wide openings, making it possible to move big-sized items like games tables and pool supplies.
  • Classic series sloped wall – as implied in the name, these are best suited for entryways with sloped sidewalls, which have been built into your home’s basement. 
  • Ultra series – it’s the most advanced type of bulkhead door, and it’s designed to offer a watertight performance and smooth operation while requiring very little maintenance. 

Constructed using polyethylene, this door is resistant to rust, and rot. And thanks to its simulated wood texture, it doesn’t need to be painted, yet it’s able to blend beautifully with your home’s exterior.

Concrete sealant

If neither of the previous approaches works, another option you can look into is using a concrete sealant.

The idea is to put this product on the cracks in your bulkhead doors; hence, seal them and prevent water from entering. Thus, the first thing you’ll need to do is check the specific spots on the door that contain these gaps. 

Before you start applying the sealant, ensure that the surface is completely dry and free of unnecessary dirt particles. 

Another thing you’ll want to do before applying the concrete sealant is to check the latest weather forecasts. 

The reason for this is that once you’ve applied the sealing material, it will require a few days to dry. If the sealant comes into contact with moisture before adhering properly, it won’t work properly.

And when it’s time to fill those cracks with the concrete sealant, we recommend using at least two coats instead of a single one. This way, the cellar door will have a strong watertight seal that doesn’t allow any moisture to penetrate.

How do I keep water from coming into my bilco door?

Preventing water from coming in through your basement door is actually not as difficult as it appears. Here is a list of things you can do to keep water from penetrating.

Proper grading

Although this approach is quite labor-intensive, it’s unavoidable if you have rainwater pooling around your bulkhead doors and entering into your basement. 

Ideally, the soil ought to slope away from your home as this allows water to flow away from the basement door as well. If this is not the case, you’ll have to undertake a re-grading project to ensure your yard is leveled well. 

So how can you tell whether your backyard needs re-grading? Simply take a walk around your site and check whether there are spots where water has pooled.

You’ll also want to check the direction in which it’s sloping. If it’s sloping towards your foundation, this is the culprit for your basement’s water leaks.

Prune overgrown shrubs

Another thing that can help to prevent these leaks is pruning nearby greenery. 

If you have any overgrown shrubs, plants, or trees, be sure to prune them, keeping their distance to your home to just four feet. Doing so will allow the soil in your yard to dry faster; thus, minimizing its risk of entering through your bulkhead door.

Install a French drain

Have you ever stopped to inspect the type of soil around your home? If you haven’t, now is a good time to do so. If it turns out to be clay soil, then it’s likely the underlying source of the water leaking through the top of your basement’s entrance. 

Here’s the deal, clay has poor drainage. So in the event that it rains, the rainwater drains very slowly. As a result, a significant portion of it pools around your walk out the basement door. 

To resolve this, consider getting a French drain installed. Keep in mind that such an activity will require expert skills and knowledge, meaning you’ll need to enlist the help of a professional. 

The installation process entails digging a trench around the perimeter of your property. This will help to channel water away from the foundation; hence, away from the bulkhead door.

Afterward, a bored hollow pipe is put in the trench, which is then covered with small-sized gravel and soil.  

Repair the cellar door

Another thing you can do to keep water from entering your basement is to inspect the bulkhead door. This will help you identify the specific area that’s allowing water to enter. 

Often, the most likely culprit are cracks either on the top or sides of the door. Thankfully, these are easy to fill using a suitable caulk, which brings us to our next point. 

Best caulk for bilco doors

When it comes to sealing bulkhead doors, you can’t use just any caulk. You ought to look for caulk that can withstand external elements like moisture, the harsh rays of the sun and more. 

In that regard, you’ll have two main options to pick from pure silicone and acrylic caulk. 

  • Pure silicone is the best choice if you’re looking for maximum durability. It’s waterproof capability is better. It’s also more flexible and resists rot better. To top it all off, it hardly ever cracks due to thermal expansion. 
  • Acrylic caulk also has its fair share of perks. For instance, it’s easier to apply compared to pure silicone. It’s also not difficult to correct if you end up making a mistake during the application process. On the downside, it doesn’t provide the best resistance against moisture and it’s susceptible to cracking if exposed to excess heat. 

Wrap Up

Wondering how to seal your bulkhead doors to prevent water from entering your basement? Well, there are three remedies you can use. 

One, you can install weather stripping material around the door. Two, you can buy a concrete sealant to seal any possible cracks or gaps. And if your current door is damaged beyond repair, consider replacing it with a brand new Bilco door. 

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House Unleashed