Water In Crawl Space

Water In Crawl Space

Water In Crawl Space

Water in the crawl space generates particular situations in the foundation that can make it unsafe, and issues like the deterioration of the air quality and the problems when trying to sell the house with this issue.

If the problem of water in the crawl space appears only when it rains, it can be easier to solve. Here we refer in a complete study, to the solution of serious issues when we detect standing water in the crawl space despite the lack of rain, without leaking water heaters, without flooding due to a sudden rise of the water table, or visible hydrostatic pressure because this pressure occurs in affected walls of the basement and not in a crawlspace.

I will discuss thoroughly all the solutions that can be applied when there is water in the crawl space, some of them involving crawlspace waterproofing, usually by installing a vapor barrier and probably a dehumidifier, but not always all of these solutions at the same time

install a sump pump, a drainage system, and encapsulate the crawlspace.

  1. Gay, Ron. 5 Steps to a Dry Basement or Crawl Space: a Guide for Homeowner & Professional: Also Included, Slab Foundations, All about Gutters, Mold and BacteriaWelkin House, 2013
  2. Chapter 6: Housing StructureCenters for Disease Control and Prevention

Treat and Prevent a Flooded Crawlspace

The crawl space is an area that elevates a house and is situated between the main floor level and the land level. A hollow space up to 4 feet of height, but usually between 2 to 4 feet of height, and unlike basements, cannot be utilized as living quarters.

The soil below that crawl space has absorption capacity for a good part of the standing water according to the soil composition, but the unabsorbed remaining evaporates upwards from the crawlspace surface towards the living quarters.

Ductwork, electrical wiring, and plumbing that run through the crawl space will often be easier to service. Crawl spaces should contain a drainage system. This will route water away from the house and cut dampness within the crawl space

The older the home with an unconditioned crawlspace, the higher likelihood of damage.   A damp or wet crawlspace can also cause hazardous mold and mildew to grow, structural wood damage, ductwork damage restricting your home’s airflow, and even sewer line or septic tank ruptures, depending on the severity. All while you can be breathing in this air from your crawlspace.

Along with creating a musty, unpleasant environment in the crawl space, they can contribute enormously to the allergen level in the living space of your home and lead to potentially serious structural damage to wood floor joists and girders.

Mold, rot, and fungi need three things to survive: organic material for food, temperatures above 40F, and a relative humidity above 60%. A simple, easy way to keep mold from your house is to seal and dehumidify the space.

The greatest defense you have is to prevent moisture damage before it’s too late through crawlspace encapsulation, or a crawlspace vapor barrier.  If you do experience a flooded crawlspace, know what to do to lessen the extent of the damage.

Especially if you have a dirt crawl space, crawl space encapsulation can help you avoid moisture in your crawl space. This process puts a crawl space vapor barrier between the exposed soil and the rest of your crawl space.

Strong, damaging storms with heavy rain can cause water to come into the crawl space. Water in your crawl space can also be the result of a plumbing malfunction. No matter how it got in there, getting it out can be tricky, but it’s crucial to dry out your crawl space to prevent potential mold growth, pest infestations, or water damage to your HVAC system or your home’s foundation. If your house has a flooded crawl space, here’s what you need to do

Step by Step Solution

The general process of controlling water in a crawl space involves setting up a perimeter within the crawl space and capturing any water that tries to infiltrate that perimeter. When water hits this border, it is diverted into gravel-filled channels and fed by gravity to a sump pump pit. The sump pump then pumps the water from the crawl space.

Practice safety first. 

Working under your home can present many hazards. Dust, dried feces, black mold, and asbestos are only a few of the contaminants you might breathe in this space. Wear breathing protection in the crawl space. Electrical wiring may be in your crawl space, so turn off your electricity at the breaker. Keep it off until the water is removed from the space. Remember that your electrical wiring may run through the crawl space. This presents a fire hazard. It also presents the potential to cause electrical shocks and damage if the water reaches an electrical outlet. It’s also advisable to hire a professional at this point because unless you are in the habit of getting under your house, there may be any number of hazards down there that you don’t know exist. Many sharp objects might be in the crawl space since builders sometimes discard nails, utility knife blades, glass, and metal here. Be sure to wear heavy gloves, knee pads, and heavy pants and long-sleeved shirts or coats.

Before you start, make sure that no water is still entering the crawl space.

you will want to check your sump-pump to ensure that it is removing the water from the crawl space. You might want to consider adding more pumps if the crawl space floods to extreme levels. Getting the water out of the crawl space is your top priority at this point. You’ll want to investigate the vapor barrier sheeting to see if the flooding is below the barrier.

Retrieve evidence for FEMA and for the insurance.

Taking photos of the damage for your flooding insurance will also be important. You want to document as much as possible for your insurance agent when you file your claim. Crawl space flooding that is part of a natural disaster may also qualify for FEMA help

Determine the source. 

The next step in remedying a wet crawl space is identifying where and how the water is getting in. As we mentioned previously, the source may be rainwater after a heavy rain or burst pipes. However, rising groundwater or condensation from warm air hitting the cool space below can also be a source of moisture. If you have a poor or no drainage system, the chances of flooding increase significantly.

The way to locate the access opening to your crawl space can be this one that follows. This is sometimes an outside hatchway in the exterior wall around the crawlspace or a hatch in the floor, often located in a closet or utility area. Equipped with a good flashlight, sturdy work clothes, and plastic sheeting to protect your clothes as you crawl about, enter the crawl space and inspect every area—both the ground and the structural members of the house above you. Look for signs of standing, puddling water on the ground, and signs of the discoloration caused by mildew and wood rot on the wooden posts, piers, and overhead structural members of the house.

If you perceive puddles of water, then there is a difficulty that needs to be taken care of. Although you may not be able to see any standing water in the crawl space, an excess of moisture could still pose a serious problem at a later stage.

 If you are unsure of where the issue may be, here are a few questions you should ask yourself to help you figure it out. What is the state of the walls in your crawlspace so we can discard hydrostatic pressure? Are they damp or are they not? If there is any water leakage from hanging pipes, have you heard or seen it before? Make sure you check upstairs. How would you describe the condition of your floors? Do you see any water stains on your carpet or wood after a heavy rain? You should inspect the gutters and downspouts on your home’s exterior. Have they been damaged, missing, or are they defective?  

I recommend that anyone who is concerned about a standing water issue in their crawl space but does not have it, should ask themselves if they smell anything out of the ordinary, it could be a dead animal inside the foundation or that was burrowing inside the concrete. It is possible that there is mildew or mold present if there is a musty smell. In the room, look for wood, and take note of its condition. Is it damp, or is it covered in brown, grey, green, or black coats that look flossy?  

While you may be able to ascertain how the water got in, a trained professional will know how to stop the water at its source. Call a restoration company that can make a service call to immediately assess the situation.

  • If your crawl space already has a plastic vapor barrier, it should be removed, rolled up, and removed through the access door.
  • The job of cleaning a flooded crawl space starts with removing the standing water. If all you have are a few puddles, use a wet-vac to suck up the water and dump it outdoors.
  • For widespread flooding that doesn’t reach more than an inch deep, you can try sweeping the water out with a push broom.

Dig the trench and fil it with gravel:

A trench is dug around the entire interior foundation, using the foundation as a guide. The trench is typically between 8 inches and 24 inches from the foundation. If the trench is any closer to the foundation, it can undermine the foundation and the home itself. The drain pipe is now covered with drain rock filling in the trench. Any remaining soil from digging the trench is now spread evenly around the crawl space.

A french drain is a trench filled with pipe and gravel that helps divert water from your crawl space.

French drains prevent water from collecting and pooling in ares around your foundation and saturating the ground below.

Install a GFCI Outlet:

Either install by yourself or subcontract an electrician to install a ground-fault protected outlet in the crawl space

Install the sump pump,

a portable sump pump is fine here. At the low end of the perimeter trench, you will then install a sump pump which will automatically activate whenever water collects in the trench.

Install a discharge pipe:

A discharge pipe will be routed from the sump pump to some appropriate discharge location outside the crawl space. Place the pump’s suction hose into the flood water and direct the drainage hose outdoors away from the house. The drainage hose should release the water far enough away from the house that it can’t flow back into the crawl space. Switch the pump on and let it run. You may have to re-position the suction hose periodically until all standing water is removed.

While the pump is running, remove all wet materials from the crawl space.

This includes any stored items, soaked insulation, and debris the flood water carried in or knocked loose from the crawl space’s interior. Wet items hold in water and lengthen the time it takes to dry the space. Water-damaged insulation is no longer efficient, so throw it out and replace it rather than trying to dry it.

Remove and discard damp fiberglass insulation.

Most insulated crawl spaces have fiberglass installed in between the floor joists. However, this building technique is becoming increasingly outdated; contractors are now beginning to use a variety of other methods, including spray foam and rigid foam insulation. In a humid environment, fiberglass will become soaked with moisture, which is pulled easily into the porous material. Wet fiberglass tends to compress and immediately loses its value as insulation. Over time, the added weight will pull it from the joists and onto the floor, where it becomes am moldy, useless mess. Do not try to dry it out. A simple rule, if it’s wet, you should remove and discard it. This includes junk, debris and other suspect fiberglass materials.

Dry it out. 

Without adequate airflow, your crawl space will not dry completely. Some homes have crawl space vents to provide airflow, but these will not allow for proper drying. In normal, dry circumstances, the air must move at least one cubic foot per 50 square feet of crawl space area. And even with a little moisture, simply placing a fan at the entrance to your crawl space won’t do the trick. Out of these first steps, calling your local restoration company for this one will likely save you the most time, money and hassles in the long run. The professionals will create a drying plan and bring in state-of-the-art drying equipment to mitigate the water damage and completely dry your crawl space. Your restoration company will also perform regular inspections and keep logs on the moisture level in your crawl space to ensure that the area is drying properly.

Warm, moving air picks up moisture more readily. To speed up the drying process, reconnect the electricity and place a source of low heat, such as a light bulb, inside the crawl space and position one or more electric fans where they’ll blow air across damp surfaces.

When all the standing water is out, you can begin drying the space more thoroughly. This means drying the wood framing, the subflooring above the crawl space, and the crawl space floor.

Once this is done, clean the surfaces inside the crawl space to discourage the spread of mold, which can contaminate your air and your dehumidifier. Check for wiring damage or other issues that would make it unsafe to use the outlets in or near the crawl space. These should be repaired before you bring in electrical equipment to help with drying.

Vacuum To Remove Water

Invest in a wet-dry vacuum. If your wet crawl space is a minor issue, meaning there’s not much water present, use a wet-dry vacuum to remove the water. A hose draws the water into the vacuum compartment to be discarded outside.

Don’t allow your crawl space to air dry after this step. Concrete is much cooler than other materials, so it holds moisture longer, and wood absorbs water almost as easily as sponge. Even if you have the pools of water cleared out, moisture will be left behind.

Use a dehumidifier to quickly dry out the space. This will remove moisture from the air and prevent mold growth. 

Simply cleaning out crawl space water, however, will not prevent any issues from resurfacing in the future. There are some other problem areas to check and possibly fix in order to prevent water in a crawl space.

Lay New Vapor Barrier:

A new 6 mil vapor barrier is laid over the ground of the crawl space to prevent vapor transfer from the ground.

Next, bring in a portable dehumidifier.

A large room dehumidifier is enough for a small crawl space, but for a larger one, you may need to rent a commercial grade model. Set the dehumidifier for between 30 to 45 percent and let it run for several hours, then check on the space. A wet crawl space could take a total of eight to 10 hours to dry. Once you have removed the water from your crawl space, it is essential that you dry out the area thoroughly. Never simply allow the space to air dry. Since wood will soak up moisture at an alarming rate, and cool concrete surfaces retain water much longer than most other materials, a significant amount of moisture will likely remain even after you have removed the puddles of water.
A dehumidifier is extremely effective at removing excess moisture from a damp crawl space. A high-quality machine will eliminate moisture in the air, drastically reducing the chances of mold or mildew development.

Even though you’ve eliminated the standing water in your crawl space, the subfloor overhead, wood framing and crawl space surface itself is still wet and needs to be dried of moisture.The best method is to use a crawl space dehumidifier and add a few fans to encourage airflow. These types of dehumidifers aren’t inexpensive, so unless you have a need to own one you may want to rent a unit or hire a professional to do the job for you.

Install The Ventilation:

Where cross ventilation in the crawl space is inadequate, new vents are installed in the exterior wall of the crawl space. Very large spaces may be equipped with electric ventilation fans to facilitate cross-ventilation within the space.

Seal Remaining Cracks

When cracks emerge in crawl spaces, they provide a passageway for water to seep in. These cracks therefore become one of the major reasons behind the existence of water in crawl spaces.

Go around your crawl space and observe any cracks and identify spots that may become weaker with the passage of time. If you find any vulnerability, apply sealants to seal them.

When you are experiencing a flooded crawlspace, seek help from a reputable professional.  Encapsulating your crawlspace or installing a vapor barrier, installing a drainage system, installing a sump pump, and redirecting your gutters and downspouts to avoid further damage.

The longer the humidity festers in your crawlspace, the greater the risk of contaminates flowing through of your home.  If your crawlspace floods during a natural disaster, you may be eligible for help from FEMA or be covered under your flood insurance.

Equipment And Materials Required

Equipment / Tools

  • Shovel
  • Tape measure
  • Wood stakes and twine
  • Flashlight


  • Bagged drainage rock
  • Sheet plastic or kraft paper rolls
  • Flexible perforated drain pipe
  • Plastic vapor barrier
  • GFCI outlet
  • Sump pump

Identifying The Source

When find standing water on the ground, it is important to identify whether the source of the water is groundwater—water flowing in or seeping up from the ground—or if it is coming from above grade, usually a leak in plumbing fixtures, drain pipes or water supply pipes running in the space below the floor of the house.

If your crawl space becomes flooded when it rains heavily, you could likely be facing drainage issues caused by inadequate guttering or downspouts, improper grading of your property, or defective window wells. It doesn’t matter if your downspouts are pointing away from the foundation if the lawn is sloping toward your home.  Address the lay of your land and make sure all downspouts flow away from the foundation and with the slope of your lawn. Depending on the slope of the property, rainwater may always collect in the same place after every storm.  If this place is near the foundation of your home, your crawlspace may be flooding.

Avoid the Clay bowl effect

When your crawl space was built, a large hole was first excavated in the hard-packed earth. The walls of your crawl space were then built, leaving a gap along the outer edges, which is backfilled with a portion of the excavated soil.

Turns out, that soil is more loosely packed than the hard-packed earth around it. Consequently, it will also be more absorbent of water, which will soak easily into this soil — especially if you have no gutter system or your gutters are clogged with rainwater. This building science phenomenon is known as the “Clay Bowl Effect”.

Insufficient grading that derives into Drainage Issues:

All houses, new or old, with basements or with crawl spaces, should regularly check the landscape grading. We recommend doing this during the Spring after the ground thaws. This is a good time to see if the Winter weather washed away any soil.

Simply walk around the perimeter of your home and look for any areas where the soil has dipped and water is pooling next to the foundation. Although, other signs may not be so obvious, if you see pooling, it’s a clear sign that there’s a problem. 

You might be surprised at how easy this problem is to fix. Simply add some soil to the lower areas and you’ll be able to build them back up to the necessary level.

The solution to a poor sloping grade is to build it up. Make sure you have a slope of at least 6-8 inches away from the foundation walls, extending for the first 6-8 feet. It’s a best practice to check the grade every spring after the ground thaws. You’ll be able to see if the winter has washed away or caused any shifting of the structure. 

The proper slope should be 1-inch for every foot. This will direct the water away from the walls of your foundation. The slope should extend outward for 6 to 8 feet.

If your home doesn’t have proper grading, surface water can be trapped up against the foundation. If this happens during a torrential rainstorm or any kind of flash flooding, the water may get into your crawl space.

In cases like this, if the water gets deep enough, it can even turn the vents of your crawl space into spouts for water to enter. This, in turn, leads to a growing amount of water building up in the crawlspace.

If any debris from water trapped against the foundation causes the vents to be clogged, regular moisture can build up as well. Either way, once water enters your crawl space, you should seek immediate remediation of the problem to prevent structural damage from occurring.

If a sump pump isn’t an option, a crawl space drainage system will also work. The drainage system is installed around the interior perimeter of the crawl space. The drain itself will typically rest against the foundation footing of the house.

If your crawl space has already flooded, then you know that layer of plastic on the floor isn’t going to do much against moisture when a severe storm hits. Crawl space flooding isn’t inevitable, though, and it’s not even particularly difficult to prevent.

Before you consider upgrading your crawl space, address the drainage around your home. Ineffective exterior drainage leads rain runoff toward your home and into your crawl space, instead of draining that water away as it should. Check your gutters and down spouts, as well as the grade of the land surrounding your home.

In the case of torrential rain, another key problem that can develop is an insufficient drainage system. In order to prevent this, you may have a French drain installed or another form of drainage. Sometimes despite our best efforts, the drainage systems around your home are overwhelmed.

When this happens, often due to weather or natural disaster, water begins to back up. This backing up uses the path of least resistance, which can lead it straight into your home. The results of this are as bad as any other form of water damage and will cost up to thousands of dollars to repair.

These changes will not totally eliminate crawlspace flooding but can reduce the severity and frequency.  The best way to protect your crawlspace is to install a sump pump, install a drainage system, and encapsulate it.

Water Entering To The Foundation Below-Grade

Below-grade water problems typically become exaggerated during certain seasons of the year, especially rainy months. If your periodic inspections show that puddling water occurs more during these periods, then it is likely you are dealing with water entering the crawlspace from below grade—either as run-off from rain or from a rising water table.

In many parts of the country, the water table is quite high, and the rainy season can cause water to rise up into standing puddles in low areas of the crawlspace

Defective, Improperly Installed or Misplaced Sump Pump

A missing, defective, improperly installed, or inadequate sump pump can allow rising groundwater to seep into your crawl space.

Sump pumps are a great way to keep water out of your crawl space. Look for a sump pump with an alarm that will alert you to the presence of water in your crawl space. It’s also a good idea to choose a sump pump with a battery back-up, so your pump will keep working in the event of a power failure. Sump pumps with a submersible pump are also a great innovation, as they’re less likely to overheat when they’re working hard.

Not all crawl spaces need one, but in flood-prone areas, these devices provide effective backup when you’re not able to completely stop water from entering.

If you choose to install a sump pump, dig a drainage channel around the edges of the crawl space. This will lead water on the floor toward the sump pump. The floor should be flat enough to prevent puddles from forming. If the floor isn’t flat, level it out.

A sump pump alone can’t keep a crawl space completely dry. If that’s your goal, you’ll need to encapsulate the crawl space. That requires covering the floor with a vapor barrier, installing vent covers, and adding an airtight door. This approach isn’t appropriate for all climates, so before you start work, consult a professional so you don’t inadvertently worsen your home’s moisture problems.

Cracked Foundations

As a house ages, it undergoes a process known as “settling”. While this process is common in all houses, over time, it can cause cracks or damage to the foundation to manifest. If any crack or gap develops, it reduces the ability of your foundation to withstand water.

This can lead to water seeping into your crawl space. If water begins to seep into your crawl space, it all but assures you will have issues with mold and even potential warping of the wood. Mold can be a threat to not just the structure of your home, but also to the health and well being of your family.

If water is allowed to sit against the wood, it can be absorbed by the wood. This causes the wood to expand, which could lead to uneven floors. The worst-case scenario in this regard is that a cracked foundation can lead to rotting of the wood because of water damage. An expensive proposition to repair.

 If the water in your crawl space seems to be coming from nowhere, then there’s a good chance that its seeping up through the ground or through the walls of the foundation.

Even when the proper systems are in place to prevent crawl space flooding, a cracked foundation will still allow water and excess moisture to enter.

Broken or Leaking Pipes

This is a typical above-grade issue and very common as well. If the water in your crawl space appears to be coming from above ground, it’s likely caused by a drain pipe or a leaking water supply pipe. An easy way to check is if you notice the water level increases in the crawl space when your water is running inside the house.

For example, the dishwasher or washing machine is running, a toilet flushes, or someone is taking a shower. If the water level in your crawl space goes up, the problem is most likely caused by your household plumbing.

If you have an unnoticed  broken pipe inside, water will trickle down and eventually find its way to your crawl space. 

If the puddling water does not seem to be affected by seasons or weather, it is possible you are dealing with above-grade sources. This is most likely caused by plumbing problems in drain pipes or water supply pipes running beneath the floor in the crawl space.1

If you notice that the pooling, puddling water is found directly below a tub, shower, toilet or other plumbing fixtures, or beneath drain pipes, you are probably dealing with a plumbing-related water problem. The good news here is that plumbing problems can be corrected by a plumber, which will be less costly than dealing with groundwater issues.

Leaking water lines can cause a flooded crawl space as well. If your home has older pipes, this increases the risk for crawl space flooding significantly. Water lines carry water to various areas throughout your home. Old, worn-out pipes, those that have been exposed to extreme temperatures, and those that were improperly sealed can sometimes fail. When broken or leaking pipes are causing your flooded crawl space, the damage to your home can be extensive, and your utility bill could go through the roof. Have a professional inspect your water lines and repair or replace those that are at risk of failing or are already leaking.

Sewage Overwhelmed And Posterior Backup Effect

Sometimes heavy rains can overwhelm a sewage system. When too much water is trying to get through a sewage system all at once, sewage can sometimes back up through drains. Additionally, clogged sewage pipes can come up through your drains as well. Sewage backup can result in crawl space contamination, extensive water damage, and health problems. If you suspect that your sewage system could be the culprit for a flooded crawl space, it is important to contact a professional for an immediate solution.

Cleaning and Clearing Downspouts and gutters 

You should be cleaning your gutters regularly, especially after a storm.  Downspouts and gutters are specifically designed to direct excess rainwater away from your home. Check to see if your drainage system is clogged, damaged, or not directing water flow in the correct direction. Blockage from leaves or other debris is going to prevent drainage.  Even if you have downspouts that are properly installed and pointing away from your foundation, if they’re not working, where is the water going? Downspouts should extend at least 10’ away from your home’s foundation.

If the gutters are not cleaned regularly the water has nowhere to go . . . other than over the side of the gutter. 

When gutters overflow, large pools of water frequently develops around your house, which can negatively affect the landscape grading that surrounds your foundation. The water can eventually seep into or even cause flooding in your crawl space. Gutters can only perform their intended purpose if they are kept clean and free of debris.

However, even if your gutters are clean and collecting water as they should, improperly placed downspouts can be a major issue. Water should be directed away from your house to prevent pooling.

Cleaning the gutters is a relatively easy task and there are a number of different tools available. The most inexpensive is the “Getter Gutter Scoop”, but you’ll need a ladder and the job itself can be a bit messy. There are also numerous pressure washer attachments such as the “AgiiMan Gutter Cleaning Too”l.

If the problem is your downspouts, you’ll need to assess the situation to determine the best way to redirect the water away from your house. There are plenty of options available such as “Downspout Flexi-Drain Extenders”, “Hinged Downspout Extenders”, and “Splash Blocks”.

Downspouts should be pointed away from the home’s foundation. They should also be accompanied by a 2-foot splash block at the bottom that guides water away. When a home doesn’t have a downspout, or has one that is facing the house, the rain water will eventually wash away the grade of your soil. Over time, the water will be directed towards the foundation and can eventually flood a basement or crawl space.

Subterranean Water Streams And Sewer Line Malfunctions

I have studied the dangers of raw sewage under house in this article, and how this affects the air quality too, where I have also precise information that extends the one you can find in this paragraph. Lime powder is not a very good option, but can be interesting for some homeowners.

Our homes have a tremendous amount of water flowing in and out daily. Except in extreme circumstances, this occurs via the plumbing of the home. Water pipes bring water in from a municipal source of well, and sewer lines take it away.

Hot water heaters are also connected via lines to the municipal water source. If any of these lines, whether they bring freshwater or sewer into the house break or clog water can be allowed in. A broken line can dump a vast amount of water into your house before you even realize something has happened.

Subterranean water issues is when water comes from underground. This problem could be the result of a broken city line. If this is the case, the city municipality will need to come onsite to fix any line problems on their end. In most cases, you won’t be responsible for the break in the line repairs, but you will need to pay for to the damage to your home.

If this occurs with a sewer line, there will be deeper sanitation issues at play. The water damage and health hazard posed by both sewer lines can be daunting. A professional will be needed to repair your lines, but also to clean up and repair the damage caused.

City water lines rupture, torrential storms pass through,  and the ground water table frequently reacts to these and other situations. 

In many cases city municipalities will need to diagnose and resolve the situation. If the flood was caused by a broken pipe, its normally the cities responsibly to fix the pipe if the problem occurred before  your water hook-up. However, if the problem was between the water hook-up and your home, you’ll likely be responsible for it’s repair. 

Subterranean water can be caused by a number of issues:

  • Clogged or damaged underground drains that were designed to carry water away from your house. The underground drains, which are designed to carry the water away from the house, have become damaged, plugged, or have an insufficient slope.
  • The drainage system is overwhelmed by a heavy storm and the overflow water is absorbed by the soil. A rain storm created too much water for your drainage system to handle. This can cause pools of water to form which can seep deep into the soil.
  • Improper drainage can create a situation where the walls of the foundation will not allow the water to pass. The walls can literally create a dam that can prevent the water from properly draining. The foundation walls are creating a dam that’s causing the surface water to seep underground. Eventually the water will find an opening in the foundation.

Depending upon how severe your problem is, you may want to contact a professional to diagnose and repair the underlying issue.

Sprinkler systems improperly arranged and gardening issues:

We all love beautiful landscaping, but unfortunately flowers, flower beds and shrubs need to be watered. Sprinkler systems, forgotten hoses that are left running, and sometimes simply over watering, can cause pooling that can eventually find its way into your crawl space. 

If a hose is left running near the side of the house, or if the shrubs and flowers are over-watered, or a sprinkler head breaks. Any of these scenarios could cause water to pool next to your foundation, with the end result being water seapage into your basement or crawl space. 

In most cases, this issue will be resolved as soon as it’s discovered by simply turning off the water or replacing the sprinkler. Many times when excessive water collects it’ll create a “hole” where it pools. Simply grab a shovel and fill in the area and check that the graded slope allows for the water to be diverted away from your foundation.

Window Wells And Ventilation Wells That Leak

Part of building a house is to waterproof the foundation. This process allows for the home to remain dry in most conditions, barring any catastrophic flooding. Over time weaknesses in that waterproofing can manifest from a variety of reasons.

Most basements and crawl spaces have vents and windows recessed into them. This area is known as the window well, and if any kind of gap or space appears in it, water will be able to seep in. Once that happens, you will have to deal with the aftermath.

Fortunately, if you are able to keep a close eye on your crawl space, you can act before the problem grows out of hand. Having your window wells, and vents, repaired will keep them functioning properly. This is also one reason why encapsulation is popular with crawlspaces as it prevents the problem from even starting.

Lack Of Flood Vents

Flood vents are another way to protect your crawl space and the rest of your house from water damage. A flood vent is a permanent opening in the wall between your crawl space and the outdoors. It’s designed to let water pass through the space freely so that it doesn’t become trapped and create pressure that can damage your walls and foundation.

If your home is built on a flood plain, these vents may be required or recommended by local or national building codes, government agencies or your insurance company. The Federal Emergency Management Administration (FEMA) recommends homes on flood planes have at least two flood vents, each positioned on a different wall. These vents should provide at least 1 inch of open space for every square foot of enclosed crawl space.

The positioning and size of flood vents you’ll need depends on your home’s floor plan and overall design. The standard-size crawl space flood vent is 16 1/4 inch by 8 1/4 inch, the same size as a standard cinder block. Two vents of this size are usually enough to vent a space of 250 square feet or less.

Poor crawl space ventilation compounds the problem by creating a mix of warm and cool air causing surface condensation, further increasing the amount of crawl space moisture under the home. This repeated wetting of building materials day after day provides the perfect environment for mold growth, termites and structural damage under your home.

Inspect The Foundation frequently

You will be required to fix the problem when it comes time to sell the house. A future buyer will be unable to obtain a loan to buy a house with water problems in the crawl space.

Since even small cracks in a foundation can result in water entry and lead to much bigger problems in the future, it’s a good idea to inspect your foundation frequently. But some problems require your attention and are not necessarily addressed by an inspection.  For example, fiberglass insulation under the floor becomes saturated and loses its capacity to resist heat transfer.

Water can sit in the crawl space for months, even years, giving a false impression that everything will be fine as long as you own the house. Over the long term, though, standing water can damage the house’s foundation; wooden beams and joists will begin to rot; various strains of mold can develop.2

Water remediation is a project best handled during dry months. While all of the work is done in protected environments such as in the house or under the house, water can continue to build up under the house and hamper work.

No Vapor Barrier

Installing a vapor barrier, along with a sump pump and drainage system, should eliminate crawlspace flooding further.  A high-quality vapor barrier is one of the most cost-effective ways to prevent health hazards and structural damage.  A vapor barrier is installed across a dirt floor to fight moisture evaporation coming into your home.

Before a crawlspace vapor barrier installation, it’s important to assess the existing damage and complete any repairs.  Our mold treatment and prevention coating kills most mold, mildew, and other biological growth that could be poisoning your home’s airflow.  Always use a qualified and experienced contractor when working on your home.

Crawlspace vapor barrier installation prevents water evaporation from rainfall and melting snow, hazardous mold and mildew growth, foundation damage, and sagging floors. 

The vapor barrier should have at least a 6 mil thickness.

Crawlspace is Very Dirty

Dirt crawl spaces tend to have moisture issues because soil likes to soak up water, whether from rain on the outside or humidity on the inside. Then the water pools at the top of the dirt. When the soil dries, the water on top evaporates and creates humidity.

Concrete Block Foundations

Concrete block foundations are the cheapest types of foundations, and they’re easiest for builders to install. That makes them very popular. However, they’re also very prone to cracks, breaks, and other problems, which create standing water underneath your house.

Leaking Water Heater

Have at least a quick visual inspection to your water heater because leaking occurs frequently in these devices, even in small ones. If you find water in the crawl space near the water heater, check to see if there are issues. Normally in these cases you will have to dispose the unit and simply replace it.

Consequences Of Water In The Crawl Space

Water in your home’s crawl space is more than just an annoyance; it can have devastating consequences for your home’s value. Standing water or even ever-present moisture in the air can create mold problems. At the extreme end, water in a crawlspace can lead to rot and decay that weaken structural members and make major architectural repairs necessary. The presence of moisture can also foster termites, carpenter ants, and other insects that can damage your home. Water under the house attracts animals that you really want to avoid such as rats and raccoons.


Mold loves moisture. And mold loves to eat dead organic materials, like wood, paper, and cardboard. The bad news is most crawl spaces have lots of moisture, as well as wood and other organic materials for mold to grow on.

Mold also likes to eat dead insects and there are usually lots of those in the crawl space too. Vents in the crawl space provide an open invitation for insects and pests. Vents also let in moisture, creating the ideal home for mold.

What’s worse is mold releases airborne spores that eventually make their way upstairs. Mold in your crawl space isn’t good for your health or your property value. Nobody wants to buy a house with mold.

Dust Mites & Pests

Dust mites thrive in humid environments, so they love homes with a dirt crawl space underneath. Dust mites are microscopic parasites that live in your bedding, carpet, and furniture. Dust mite droppings float in the air and can trigger allergies and asthma. Other pests, like termites, spiders, mice, rats, and snakes love damp, dirt crawl spaces too.

FHA Appraisals And Resale Value

Mold can greatly affect the appraisal value of a home. FHA appraisers, for example, are required not only to note if mold is growing in a home, but also the type of mold and its location. If you find that the mold growing in the home is black mold, there are a few things you should know: toxic black mold can cause permanent damage to your health and in extreme cases has even lead to death.

Large overgrowths of mold and mold in unusual locations are especially likely to lower a home’s value. If the FHA appraiser finds that the mold overgrowth is dangerous, you might be required to remove the mold before you can get an FHA loan.

Costs Of Fixing the Issue

Clogged or misdirected gutters and downspouts is the most common reason for crawl space moisture problems. Replacing and redirecting a gutter can cost up to $300. Foundation cracks are one of the most costly problems to fix. This type of repair requires a professional, and can range anywhere from $500-$15,000.

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BY M. Kogan

Hello, I am Marcio. I am an architect and designer, alma mater is Mackenzie. Retired in theory, but an architect never retires completely. Along with architectural projects, I am a filmmaker and have completed some short documentaries. Filmmaking and design are my passions. In HomeQN I write about home decoration and foundations. The goal is to teach homeowners to DYI as much as possible, and when this is not possible, enable them through knowledge, to evaluate service quotations and choose the best service technicians.

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