A barndominium, or “barndo,” is often a renovated barn repurposed into a residential home. However, many owners use a barndo kit.
Your new-build project requires foundations complying with the local building codes to protect the construction against extreme weather, seismic disturbances, and ground subsidence.
This guide asks if barndominiums can have a pier-and-beam foundation, producing a crawl-space between the soil and the suspended wooden floor.
However, before choosing, confirm with your building permit office whether they allow pier-and-beam foundations in your locality.
What Is A Barndominium Crawl-Space?
A crawl-space is precisely what it sounds like. It’s a space where someone can crawl under the barndo’s first floor.
Some people like their home at ground level (grade), so excavate about 3 ft. to provide the crawl-space. In contrast, others raise the barndo above grade and have a ground-level crawl-space. It’s up to you as long as you comply with building codes.
The crawl-space underneath the barndo’s floor allows for better access to plumbing, insulation, ventilation ducts, and electrical cabling. Sometimes, depending on the requirements of your building codes, you may keep the soil uncovered or cover it with a concrete slab.
Generally, you have significant benefits when covering with concrete, and we recommend you do this, even if your codes don’t require it.
Barndominium Crawl-space Benefits
A crawl-space beneath a barndominium has several advantages, but these might not be the best option for your project.
Let’s consider the benefits before deciding.
Enhanced Air Circulation and Ventilation
Ventilation has two main benefits:
- It keeps the barndo cool in the summer.
- It maintains a dry space, reducing dampness, mold, and rot.
Crawl-space Encapsulation
Unfortunately, air circulation from outside also has the potential to make your home cold during the winter. So, if necessary, you’ll need extra insulation and the crawl-space encapsulated.
This process consists of lining the crawl-space with heavy-duty polyethylene sheet, covering all floors, walls, and the underside of the suspended floor above. Ensure all welded joints prevent water ingress, drafts, and pests.
However, encapsulation lasts about 10-15 years or less, depending on the preparation, quality of material, and installation process. So, it needs annual inspections for issues with sealed joints, etc.
Typically, professional encapsulation of a typical American home costs $5,500-$15,000.
However, you can do it yourself. Here’s a beginner’s guide YouTube video from Bay Crawl Space Foundation Repair.
Easier Access to Plumbing and Electrical Systems
Usually, we hide plumbing, electrical, and HVAC services within our homes as they’re generally unsightly.
If we have slab foundations, electrical and HVAC service must run through cavities in the foundation and up the walls. In comparison, we embed plumbing into the concrete slab.
Yes, this protects them from damage. But, if the services need maintenance, we must dig up the concrete floor to reach the problem area.
On the other hand, crawl-spaces allow us to hide these services under the suspended floor and divert them to whichever room is necessary. Doing this gives contractors and technicians easy access to essential repairs and maintenance.
Potential for Additional Storage Space
If your home is anything like ours, there’s never enough storage space. Fortunately, if you take certain precautions, the crawl-space becomes a valuable place to keep those items you need now and again.
To prevent damage to your stored belongings, ensure the crawl-space is free of dampness, mold, and pests.
Uneven Ground
A crawl-space is ideal when building a barndominium on uneven ground, like a shallow slope.
As long as you maintain enough headroom to access the underside of the suspended floor, it doesn’t matter if the concrete slab is sloping or stepped.
Flood Defense
Some locations have occasional floods. An ideal way to prevent floodwater from damaging your home is to place the barndo on raised piers-and-beams and create a crawl-space beneath it.
However, don’t use lumber frames to support the barndo’s floor joists if you do this. Instead, build concrete or masonry piers and protect the floor joists from water damage by incorporating a damp-proofing membrane.
Remember to raise the crawl-space to account for typical flood depths.
Additional Insulation
When using a crawl-space under your barndo, you probably have already laid an insulated concrete slab as its floor.
Furthermore, add a vapor barrier and spray foam insulation to the underside of the suspended wooden floor for extra warmth.
Barndominium Crawl-space vs. Slab Foundation
Slab foundations, or slab-on-grade foundations, are thick concrete slabs providing a barndo’s subfloor. Building codes in most states require the slab to have a thermally insulating layer, protecting against ground temperature fluctuations.
Around the slab’s perimeter and incorporated within it are the footings that support the weight of the barndo’s exterior load-bearing shell.
Then, pour the slab and footing concrete simultaneously so that the concrete is one unbroken unit, often called a monolithic slab. Embed the barndo’s steel posts in the footing concrete.
In contrast, a pier and beam foundation has concrete footing and a slab, like slab-on-grade foundation. But, to create the crawl-space, we build masonry walls from the footings, topped with concrete beams to support the barndo.
Additionally, we pour extra footings across the crawl-space floor, where we build masonry piers supporting the suspended floor. Thus, we reduce the joists’ span, preventing the floor from flexing.
Comparing Your Options
Before deciding whether to use a slab or crawl-space, check with your local building codes; you may not have a choice. Also, remember slab foundations are best used in wet, humid, and hot regions because they suffer less structural damage than other foundation types.
In comparison, crawl-spaces work better in cold, dry locations.
Cost Comparison: Crawl-space vs. Slab
Building a slab foundation is more affordable than providing a crawl-space. Typically, slab foundations cost at least $5.50-$13.50/sq. ft. In contrast, crawl-spaces cost at least $7-$11.50/sq. ft.
Prices vary depending on several factors, such as excavation, footing depth, slab thickness, and concrete strength.
Maintenance for Both Foundations
Whichever foundation you choose, organize regular inspections and maintenance to keep them in good condition.
However, inspection will be significantly easier using a crawl-space as the foundations are more accessible, and cracks, settlement, subsidence, and water damage are more readily discovered.
Slab Foundation
Slab foundations don’t need much maintenance. But, check for water damage to the concrete and underlying soil.
Ensure gutters drain away from the house and check on vines and tree roots, which can find the smallest cracks. Install a root barrier to prevent roots from gaining hold and entering your home.
Also, because the slab contacts your home’s interior, keep a constant indoor temperature so the concrete doesn’t expand and shrink with temperature changes.
Crawl-space Foundation
Crawl-spaces need regular inspections and maintenance. Encapsulation helps prevent moisture problems, but you can’t use the space for storage.
Also, watch for pests, like insects and rodents. They may attack the suspended wood floor above the space.
Generally, keep crawl-spaces clean and tidy to assist inspections, so routinely clean them once or twice a year.
Lifespan and Durability Differences
The lifespan and durability of your foundation depend on the construction standard, thorough inspections, and regular maintenance.
Lifespan
By preventing moisture problems and issues with tree roots, concrete can last for decades, even reaching 100 years or more, if built correctly.
- Slab Foundation – Usually, slab foundations can last as long as the house, if not longer. Do regular inspections and maintenance, such as water management, by diverting rainwater from the foundation. Continual soil flood and drought cycles cause soil subsidence and cracks in the concrete.
- Crawl-space Foundation – Typically, crawl-spaces last up to 50 years, depending on maintenance and keeping them dry. Crawl-spaces also attract insects and animal pests, so inspect regularly for signs of infestation and use pest control.
Durability
Both crawl-spaces and slab foundations are very durable.
Slabs have longer lifespans because they don’t need as much maintenance. In comparison, crawl-spaces are less durable because there’s more chance of potential problems.
- Slab Foundation – Concrete slabs are durable and can last 100 years or more when constructed correctly. However, slabs can crack if the supporting soil moves, shrinks, or you experience an earthquake. They’re also susceptible to tree root damage.
- Crawl-space Foundation – Generally, crawl-spaces are less durable than slabs. However, they withstand earthquake zones because they can handle soil movement better. Furthermore, crawl-spaces suffer from pest and rodent infestation, and you should monitor the area for these nuisances. Sometimes, depending on your location, it may help to add extra insulation or encapsulate the space (or both). Thus keeping moisture out and heat in the house.
Challenges of Installing a Crawl-space
Installing a crawl-space beneath your home can cause several issues, overcome with careful planning.
Ground Moisture
Exposed soil floors cause ground moisture ingress.
Typically, from rainfall soaking into the ground, incorrect landscaping, and minimal drainage. You won’t have an issue if you remove the cause by preventing water ingress.
Alternatively, cover the soil with a vapor barrier and sealed concrete. If you still have problems, consider encapsulation.
Condensation
Condensation occurs when warm, moisture-laden air meets cold air and surfaces. Therefore, when warm, humid air comes in from outside through vents, it loses its moisture on surfaces, causing drips and puddles.
Furthermore, condensation also forms on exposed cold water pipes or HVAC ducts. Condensation also occurs in winter when cold air enters the crawl-space and meets warm moisture-laden air and hot water pipes, with the same result.
To solve this, insulate pipes and air ducts, encapsulate the crawl-space, and, if necessary, use dehumidifiers.
MoldÂ
Mold and mildew spores occur everywhere in nature, and you can’t eliminate them.
However, give them an underground, warm, damp environment, and they’ll grow and multiply. Fungal infestations like these are worse when wood is available, causing dry rot.
The solution is to reduce the moisture levels within the crawl-space, thus keeping the wood moisture content low.
Warping
Crawl-spaces are usually below a wooden floor. Therefore, if they contain humid air, this seeps into the wood and causes warping and cracking.
The solution is to maintain a low humidity level in the crawl-space.
Pests
All kinds of insects and animals like to live in your crawl-space. With holes in the foundations or outside vents, these lodgers will live in the insulation and other cozy places.
Control the moisture levels, reduce access, and make your crawl-space less attractive.
Higher Initial Construction Costs
Crawl-spaces cost more than a slab to build and take additional time, materials, and manpower to finish.
So, think hard about the extra costs at the planning stage.
Slab Foundations
Slab foundations cost at least $5.50-$13.50/sq. ft., depending on several factors. Therefore, a 60 ft. x 40 ft. slab costs $13,200-$32,500 minimum.
Typically, the slab’s thickness and footing depth affect the total.
Crawl-space
This foundation costs at least $7-$11.50/sq. ft., depending on the usual factors. Therefore, a 60 ft. x 40 ft. pier-and-beam foundation costs $16,800-$27,600 minimum.
However, additional costs include:
- Vapor barrier – $0.5/sq. ft.
- Insulation – $1-$5/sq. ft.
- Additional masonry.
Regular Maintenance and Inspections
Inspecting and correctly maintaining your barndo’s foundations is essential to ensure they don’t experience cracking or subsidence. With a slab foundation, you can only examine the visible sections, usually around the edge of the slab and the surrounding soil.
In comparison, a pier-and-beam foundation allows the examination of cracks and gaps by entering the crawl-space.
Inspect both foundation types annually or after a severe drought, flood, ice, extreme weather, or earthquake for damage, movement, and standing water.
8 Best Practices for Barndo Crawl-space Installation
To install the pier-and-beam foundation and crawl-space correctly, use industry-standard best practices:
1. Footings
Ensure the lowest part of the footings is at least 12″ below the frost line. Generally, the local building codes specify the depth.
2. Concrete Strength
Use the correct strength concrete for your size barndo and the locality’s environmental conditions.
Typically, concrete strength should be 2,500psi-4,000psi, depending on a structural engineer’s calculations.
3. Concrete Thickness
Use at least 4″ thick concrete, thicker for footings.
4. Crawl-space Floor
Building codes specify whether to cover the crawl-space floor with concrete.
Even when optional, we recommend sealing the underlying soil with insulation, vapor barrier, and at least 4″ of concrete.
5. Waterproofing and Moisture Control
Crawl-spaces become damp even in dry weather due to groundwater and condensation.
If the available ventilation isn’t enough to dry out the space, the dampness can weaken the barndo’s structure.
6. Ensuring Proper Insulation
Consult the building codes to determine the thickness and R-value of the thermal insulation needed within the crawl-space.
Each climate zone has unique requirements, and you must adhere to them.
7. The Importance of Ventilation
Although thoroughly ventilating the crawl-space is essential in summer. Vents cause heat loss during the winter.
Therefore, install additional insulation, such as spray foam, to the floor joists and, if necessary, consider encapsulating the crawl-space.
8. Look Out for Pest Infestations
Crawl-spaces are safe, sheltered spaces for creatures to live. Keep the crawl-space clean and dry to prevent infestations.
If you notice the beginnings of an infestation, call the pest control contractor immediately.
Frequently Asked Questions
How deep should a barndominium crawl-space be?
The height is often two to three feet tall, providing enough space for a grown person to crawl inside.
If you make it higher, it’ll be a basement.
Is it cheaper to build with a crawl-space or a slab?
Slab foundations are more affordable than pier-and-beam foundations.
Typically, slabs cost at least $5.50-$13.50/sq. ft. In contrast, pier-and-beam foundations cost at least $5.50-$13.50/sq. ft.
However, these prices vary with design complexity, materials, and labor.
How do I protect my barndo crawl-space from pests?
Protect your barndo foundation by keeping the crawl-space clean and prevent standing water from accumulating.
If you see signs of insects or rodents, call the pest control contractor to deal with it.
What Next?
Most barndominiums have slab foundations. However, these tend to crack in icy conditions, and dealing with plumbing problems is challenging when the pipes are buried in concrete. In contrast, pier-and-beam foundations and their crawl-spaces offer room for contractors to run electrical cabling, plumbing, and HVAC ducts with room for maintenance. Furthermore, a crawl-space:
- Allows room for additional thermal insulation to improve your home’s energy efficiency and save on costs.
- Footings extend deeper into the ground, giving additional stability and reduced frost line damage.
However, you may not have a choice of foundation in your locality. Your local building codes may specify the type to use.
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