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A Guide to Crawl Spaces

Whether you’re building a new home or buying an old one, there are plenty of things you have to consider — what sort of square footage do I need, how many rooms and bathrooms do I want, and what type of countertops for the kitchen?

One thing a lot of people overlook is the crawl space, a feature common to many homes and one you may want to consider adding to your design.

If you’ve never given crawl spaces a thought before, take some time to learn about them before beginning your home search or construction project. What is a crawl space and what do you need to know about them?

What is a Crawl Space?

First, what is a crawl space? The specifics will vary depending on the exact design of your home, but in general, a crawl space is defined as a small space below the ground floor of your home — usually unfinished and hollow. It’s a useful place for storing the guts of your HVAC system, as well as ductwork and plumbing.

  • These spaces get their name from the fact that they’re small enough to crawl into — which is the only way to access them.
  • Some may even be small enough that you have to low-crawl on your belly to get to any of the pipes or HVAC equipment that may be installed down there.

Crawl Space Waterproofing

Crawl spaces are ideal for building homes where flooding is a possibility, but in humid environments, water in a crawl space can lead to mold, mildew, pests, and potential damage to a home. Below are some techniques for crawl space waterproofing and preventing moisture buildup:

  • look at the ambient humidity in the outside air

    If you live in an area where the humidity is constantly high, then increasing the ventilation of your crawl space could make the problem worse by bringing in more humid air.

  • Check for moisture sources

    If you live in a dry environment, take some time to inspect your crawl space to see if you can figure out where the humidity is coming from.

    • Are your rain gutters draining into your crawl space?

    • Is there water evaporating into your crawl space from damp soil?

    • Is there some other source of water that is causing moisture buildup?

    Once you address the problem, it should be easier to keep your crawl space dry.

  • Proper exterior drainage

    Make sure everything that generates water or wastewater is draining away from your home. This includes gutters and rain drainage, air conditioner condensate lines, and any other wastewater lines.

  • Sump pump

    Installing a sump pump inside of the crawl space will help remove any standing water and direct it away from the house. Make sure it has a battery backup.

  • Dehumidifier

    There are some professionals who suggest putting a dehumidifier in your crawl space if you’re experiencing high levels of moisture, but make sure you consult with a professional before installing one.

    They are not appropriate for all applications and could actually do more harm than good.

  • VAPOR BARRIER

    If the floor of your crawl space is unfinished consider installing a crawl space vapor barrier. It’s basically sheet plastic that prevents moisture from evaporating from the soil into the enclosed space.

    These need to be installed properly in order to create an ideal seal — consider contracting a professional to have a vapor barrier installed if soil moisture is a problem.

  • Crawl space encapsulation

    Seal off any draft points such as vents, walls, foundation, and piers with crawl space encapsulation to make it a clean and dry part of the house.

    Not only does this make it more pleasant if you have to head down into the crawl space, but it also helps reduce moisture and crawl space mold.

    Consult a professional before encapsulating a crawl space, as not all spaces are well suited for it.

Crawl Space Repair

Since it is so vital to a home’s structural integrity in its position under a home, any crawl space structural repairs need to be addressed as quickly as possible. Examples of some crawl space repairs include support beams that are failing, sagging, or even rotting.

Pests and critters can also get in there and damage things like ducts, wires, and vapor barriers.

Crawl space repair professionals can fix these issues in as little as a couple of days.

The average cost of crawl space repairs is around $6,000 with smaller issues such as minor sinking issues starting around $500 and larger issues like vapor barrier and encapsulation system repairs getting up over $10,000.

Crawl Space Cleaning

Since crawl spaces are often difficult to access, they are often a very neglected area of a house. However, it is important to regularly get down in there and perform inspections as crawl spaces are vulnerable to issues like flooding and pest infestations, which can lead to mold growth, water damage, rotting wood, and unwanted odors.

They can also get bogged down with a lot of dirt, debris, and animal waste, which can limit visibility and cause other issues. Asbestos is common in crawl spaces as well and should be cleaned out for the sake of the health of the people living inside of the home.

Since handling some of the materials that can be found in crawl spaces can be hazardous, it is recommended to call in professionals with appropriate safety gear to perform a crawl space cleaning task.

Depending on the size and scope of the crawl space in need of work,the cost of crawl space cleaning can range between $500 and $4,500.

what are the pros of crawl spaces?

Working on things like your HVAC system, electrical system, plumbing or other areas can be tricky once your home is complete — leaky pipes can require you to knock out walls, and problems with ducting can necessitate a trip into the attic

  • With a crawl space under your home, much of the equipment that might need to be repaired or replaced is much more easily accessible, reducing the amount of damage done during any repair attempts.

  • This accessibility also makes it easier for your pest control service to do termite inspections. It’s much easier for them to inspect the frame of the house if they can access it from beneath.

  • You can also use your crawl space for storage. While they might not provide as much space as a basement could, they’re useful in areas where basements are not possible — such as in Florida, where basements are commonly flooded by the local high water table.

  • They also don’t retain moisture like basements do, because there is no sand or soil around your crawl space that could potentially retain water during rainy months.

    Just make sure your crawl space is well ventilated to ensure no ambient moisture has a chance to collect, especially in humid environments.

  • Crawl spaces tend to be cheaper than constructing a basement. It is estimated that the average cost of a basement can run anywhere from $75,000 to $150,000 on top of the cost of the rest of your new home. A crawl space for the same-size home can be completed for as little as $8,000 to $25,000.

  • They are also recommended for homes in earthquake-prone areas. A crawl space gives your home a lot more flexibility than a solid concrete slab does, which reduces the chances of an earthquake causing irreparable damage to your home.

  • Crawl spaces are also ideal for building on sloped land, or building on land that is prone to flooding. Instead of flooding into the home, the crawl space gives you a bit more security and keeps your home safe in the event of a flood.

what are the Cons of crawl spaces?

While there are a lot of perks to having a crawl space, they’re not the perfect solution for everyone. What are some of the cons of having a crawl space?

  • First, they’re not as energy-efficient as a slab foundation or even a basement. Even if they’re well insulated, crawl spaces can’t hold a candle to the kind of insulation offered by a slab.

  • They’re also not recommended for humid environments. Even if ventilation is up to par, water can accumulate in a crawl space that can contribute to mold or mildew growth.

  • This moisture can also move up into the walls of the home. This is known as the stack effect, and can over time potentially compromise the home’s entire structure, causing cracks in the walls.

    You usually only see this happen in basements or in areas where there are walls that are partially underground. With a crawl space, that effect can be translated upward.

  • In addition to mold and mildew, an unventilated crawl space can also easily become home to pests like termites, mice and rats — just to name a few. These pests love a dark and damp environment, so an unventilated crawl space becomes a haven for them.

  • Crawl spaces also take longer to construct, which can increase your overall construction timetable. This isn’t a huge issue, but if you’re not on a short deadline, this isn’t something you really need to worry about.

  • These spaces also aren’t a good idea for homes inhabited by individuals who are mobility challenged. They raise the house up, making it harder to get into, and the crawl spaces themselves are difficult or impossible to access for someone who has problems with mobility.

Crawl Space Insulation

While crawl spaces can’t offer the kind of insulation that a solid slab foundation does, that doesn’t mean you need to bleed heat or cold. Good insulation in your crawl space is important to help keep your home temperature regulated and reduce your energy costs.

If you’re building a new home with a crawl space, chances are insulation is included in the construction costs — the energy conservation building codes that were finalized in 1990 mean insulation is mandatory.

The Department of Energy recommends an insulation of rating R-9 or higher in floors, so make sure you talk that over with your contractor.

If your home was built before those energy codes were finalized or hasn’t been updated in some time, give your crawl space a thorough inspection. Dangling, deteriorated or missing insulation are all good indicators that it’s time to get some work done.

The type of insulation you need will depend heavily on the area where you live.

Warmer or moderate climates may only need insulation between the floor jousts — located between the supports and the subfloor.

If you’ve got enough ventilation and the overall moisture levels are low, this is more than enough insulation to keep your feet warm in the winter and reduce your energy costs.

For extremely cold climates, spray insulation that seals all the places where cold air could cause heat loss or damage pipes is a popular option.

It’s more expensive than other alternatives, at about $5 per square foot, but it also insulates all the pipes that could potentially be damaged by cold temperatures.

The first time you make it through a freezing winter without any burst pipes, your insulation will have paid for itself.

Should I Buy or Build a Home With a Crawl Space?

When it comes down to it, should you build or buy a home with a crawl space? Ask yourself these questions:

  • Is my home in an area that’s prone to floods or earthquakes? If the answer is yes, consider a home with a crawl space — we’ve already covered how these homes are preferred for areas that are prone to flooding or earthquakes.
  • Is my home in a highly humid or damp environment? If the answer is yes, you could still consider a home with a crawl space if you’re willing to take the time to ensure it’s kept dry. If not, consider a slab home instead — you lose out on some storage space but it keeps your house dryer.
  • Am I looking at buying an older house with a crawl space? Make sure you consider the insulation that’s currently installed, as well as the added cost of installing new insulating in the floor to ensure your energy costs are lower.
  • Do I need additional storage without worrying about an attic or basement? While crawl spaces don’t provide a ton of space, they do give you more storage without worrying about having to keep a basement dry.
  • Am I able to keep up with moisture control in my crawl space? If you’re not able or willing to keep up with the control of water in your crawl space, it might be better to purchase or build a home without one. You can also buy a home that is already designed to keep the moisture levels down.
  • Do I need a crawl space? If you’re purchasing an older home, especially one that might need repairs in the not too distant future, you can definitely use a home with a crawl space. For newer homes, you can take it or leave it.

If you’re building a new home, make sure you talk to your contractors.

They will have the best information available for your locale. Ask them if they think a crawl space is good for your area or would be the best option for your new home. They will have the most up-to-date information, and will let you know whether you should be building a crawl space, a slab, or some combination of the two.

If you live in a wet environment or in areas where you can’t build a basement, a crawl space can be a great alterNative.

Crawl spaces are a fantastic way to keep your home insulated and protected while enjoying some extra storage space in areas where you can’t build a basement or additional underground storage.

They do take some work, especially if you’re inheriting a crawl space in an older house that isn’t insulated or hasn’t been maintained.

But if you’re in an area where crawl spaces can be beneficial, you should consider buying or building a house with one. Take the time to talk to your contractor, a home inspector, or an engineer to determine whether a crawl space is the best choice for your new home.