How to Build and Install a Crawl Space Access Door

As a renter, it's easy to underestimate the importance of keeping a clean and dry crawlspace. When you begin the homeownership adventure, it's harder to ignore the space under your home. Creating a crawl space access door that is safe and secure is essential to your home's overall health and safety.

Your crawl space access door should be secure and help keep pests, rodents, and moisture out of the crawl space, but it doesn't have to be ugly and dull. There are plenty of excellent crawl space door ideas, and most are within the skills of most DIYers.

Why Does Your Crawl Space Need a Door?

You don't have to have a door in your crawl space in the most technical sense. However, to make it accessible when you need to maintain or repair water lines, gas lines, and insulation, a secure door will help you significantly.

Your home may have a crawl space access point inside your home, usually through the floor of a closet or through a hole or door in your basement wall. If you have an exterior crawl space door, it's likely the sidewall of your foundation.

The most significant reason for your crawl space access to have a secure cover is safety. The underbelly of your home isn't somewhere you want kids or pets playing, nor is it a place you should have moisture or pests. A safely latched access door can keep rodents, bugs, and water out if the space is well insulated.

How Large Should a Crawl Space Access Door Be?

First, determine the size of the current access opening, if you have one. The size should easily accommodate an average male, as fairly burly adult men primarily staff the industry. Your door will be a few inches larger than the initial opening to create a lip for the door to rest on the frame.

According to the International Residential Code, the crawl space access door needs to be at least 18 x 24 inches for safe passage into the crawlspace with tools and protective equipment.

Crawl Space Door Installation

While installation or replacement of a crawl space door is something you can hire a contractor for, the process isn't overly complex if you want to tackle it on your own. You'll need to determine where your current entry point is and assess the options.

Materials You Can Use to Build Your Crawl Space Access Door

Most people choose to build their interior access door from sturdy construction-grade wood and then cover it with the flooring treatment used in the surrounding places.

For example, if you have laminate wood floors in your hallway and choose to replace your access door in your coat closet, you can frame it with 2x4s, surface it with a sturdy plank of MDF, and then lay matching wood laminate over the door.

An exterior access door should be framed in the same strong material as an interior door, but the coverage can differ. Some people seal the access door with waterproof paint or epoxy material, and others choose to face it with sidewall planking or concrete veneers.

Building a Crawl Space Door

Building the door is a straightforward process with some essential tools and a basic understanding of your tools.

Build Your Frame

Build your frame by measuring and recording the length and width of the access point to the crawl space. You can choose to reinforce the frame with cross beams or corner brackets for extra safety, but this is not necessary in most cases. If the access door, which may remind you of a trap door, will be in a high traffic area, it may be best to reinforce the door.

Attach Door Face

Cut your door face at least 1 inch larger in all four directions. Secure the front to the frame of the door. Sand any rough edges, and determine your handle option. Choose something that works for you and your family. Some people opt for a simple hole in the door to pull with their finger, while others install an actual cabinet door pull.

Attach Hinges

Attach two solid hinges approximately three inches from the corner of the face of the door and mark placement for the floor surface. Secure the hinge to the floor, ensuring the door opens toward the inside of your house and doesn't catch on the walls or the opening.

Locking Crawl Space Doors

Some homeowners choose to install a lock system to hold the door open when under the house and keep it closed when they don't need access. You can do this with a D-style latch, like on a steamer trunk or other locking box, or with a standard hook and eye system. You can use a carabiner to close the door or install a padlock

Finish Surface

Finish the door with the surface cover of your choice. Some ideas include laminate floor, linoleum, or carpet. Follow the install instructions on your material of choice.

Weather Seal Exterior Doors

Building and installing a crawl space access door is the same for an exterior access point as for the interior, except that you'll need to seal the door against the elements to keep it dry and safe.

Achieving an Air-Tight Seal Against the Elements

An airtight seal isn't essential, but it will help you reduce the chances of barrier damage, leaking, and other costly issues.

You can achieve this airtight closure on your crawl space access door by installing weather strip foam insulation around the edges of the door and using high-quality silicone caulking around any cracks or gaps in the vents or concrete joints.

Ensure that your crawl space has full plastic coverage, especially if the floor is soil or gravel.

How to Avoid Moisture Damage, Mildew, and Mold in Your Crawl Space

Before you replace your crawl space access door and forget it exists until a new crisis arises, ensure you're doing all you can to protect your home from damage caused by moisture under the floor.

It's well known that standing water and water leaks can cause mold and mildew, but excessive moisture can cause cracking in the foundation and footings, rot in your floor joists and other supports, and create a prime space for things like mildew and fungus to thrive.

Mushrooms are good on your pizza, not in your crawl space. Additionally, pooled water under your home can cause infestations of bugs and algae.

Install a Full Moisture Barrier

Once you've dried out as much dampness from your crawl space as you can and adequately insulated the joists and the underside of the ground floor, you can install a full vapor and moisture barrier that seals the area from groundwater leaks.

You can install a basic system, which protects the space from groundwater infiltrating your room, or you can choose to have a professional seal every nook and cranny of your crawl space.

Install a Proper Ventilation or Air Conditioning System

Keeping air movement in the depths of your crawl space is a crucial component of keeping the area dry. You can purchase and install a fan system or dehumidifier system that runs continuously like your furnace, and it will solve many of your moisture-related stressors.

Once you have a solid vapor barrier and a proper airflow system, you can remove and block the vents in your home's foundation and prevent water from leaking into the space. These vents were necessary in the past because the airflow systems were uncommon.

How to Avoid Pest Damage and Infestation

As mentioned above, pests like mosquitos and toxic growth can make themselves at home in standing water under your house. Additionally, rats love looking for food scraps that escape your kitchen disposal pipes, leading to a robust colony of rodents in your crawl space.

Rats and other rodents can chew through plumbing pipes, creating catastrophic failure points and damaging the crawl space insulation and vapor barriers.

Your home will stay relatively pest-free and dry with proper maintenance of your underground utilities and a full wrap vapor barrier. You can add an extra layer of protection by occasionally entering the crawl space and putting down rodent traps.

Avoiding Structural Damage in Your Crawl Space

A proper access cover on your crawl space does more than hide the cavern under your home; it also protects the foundation and joists in your home from structural damage caused by moisture and pests.

By keeping the space sealed from termites, carpenter bees, and other wood damaging insects, you'll have less cause for concern regarding your foundation feet and joists.

Additionally, when you keep your crawl space properly vapor sealed, moisture can't infiltrate your foundation walls and cause cracks from the contraction and expansion of the water in the porous material.

Bonus Benefits of a Solid Crawl Space Access Door

In addition to the primary benefits already discussed, having an adequately insulated crawl space, including the access door, can save you a significant handful of cash on your heating and cooling bills.

You'll also experience less outside noise coming up from your floor and fewer instances of asthma and allergies causing pain and exacerbating health issues.

How Can You Keep the Crawl Space Access Door In Top Condition

During your annual household maintenance inspection, check the health of your crawl space door and crawl space vapor barrier. Watch for the following signs of damage that indicate it's time to replace the door.

Water Damage to the Door Surface

Untreated, unsealed, or damaged wood can warp and begin to delaminate. If you notice these issues, it's a sign of excessive humidity, poor circulation, or a leak.

First, remove the door, and determine the origins of the moisture. Then you can remedy the issue and replace the door with a new, adequately sealed door. You can buy a door kit or build your own following the above directions.

Peeling or Flaking Insulation Around the Door

If your crawl space door uses weatherstrip insulation, its adhesive backing can fail, and the foam can peel away. If this happens, pull out the rest of the old insulation strip, clean the surface, and apply a new weather seal.

If the door uses rigid foam or expanding foam, you'll need to remove the foam, clean and smooth the surface, and re-install a new foam layer. Most commonly, these forms of insulation are damaged by impacts and pests chewing on them.

Mold Forming at the Entrance to the Crawl Space

Mold results from moisture in the floorboards, framework, insulation, or surrounding areas. Mold can cause respiratory issues, trigger allergies and asthma, and even result in more chronic health situations if left untreated.

Spores from mold can spread to other parts of the house and worsen the problem. The best course of action is to figure out the source of the moisture, remedy the issue, and dehumidify the space. You may need to contract with a mold remediation team to ensure it's all gone before sealing the area again.

Foul Smells Coming from the Crawl Space

Foul smells can be anything from rotting food from a broken garbage disposal system to a dead pest that's gotten stuck under the house. Once you've discovered the cause, fix the issue, and seal the crawl space. This is a great chance to inspect all vent openings and fill any gaps in the crawl space that may be contributing to leaks and pest intrusion.

Other Crawl Space Projects

Some frequent crawlspace projects include draining them of water and sealing them with moisture barriers.

If you're up for an even bigger adventure, you may choose to add to your home by digging out a basement or finishing one to create a livable apartment.

Crawl Space Access Door FAQ

What kind of wood do you use for a crawl space door?

Crawl space doors can be made from any number of materials but wood is one popular option. Pressure-treated lumber is a common crawl space door choice because it's resistant to rot and termites.

Does a crawl space door need to be vented?

Mold and mildew grow in dark and damp areas. These growths can actually cause health problems in humans, so you do not want this.

Ventilation will help keep your crawl space dry and prevent fungal growth like this. If your crawl space door is not vented, there needs to be ventilation somewhere else or you will need to find another solution for keeping the crawl space dry.

Should you cover crawl space vents in winter?

Covering crawl space vents will help keep cold air out of the crawl space, which is what you want. Cold air can damage air ducts and pipes in the crawl space by causing them to freeze, which can lead to cracking and breaking that causes bigger problems and leaks.

Is it normal to have a little water in a crawl space?

The last thing you want to see in your crawl space is water. Moisture can cause bacterial growth like mold and mildew, which can cause you to become physically ill and certainly make the crawl space dangerously unpleasant.

Breathing mold spores is not good for you, after all. Water in the crawl space is a sign that you don't have proper drainage or ventilation for this area.

What absorbs moisture in a crawl space?

There are many ways to keep crawl spaces dryer. A dehumidifier or fan will help keep the area dry.

You can also use sandbags to absorb moisture in the space. Make sure the crawl space is ventilated, which usually means there are openings in the door to let air in and out of the space.