Barndominiums have taken the housing world by storm, combining rustic charm with modern design and functionality. However, because of their unique structure—often built with metal frames, large open spaces, and concrete slabs—barndominiums are particularly susceptible to moisture problems. If not addressed properly, excess moisture can lead to mold, structural damage, corrosion, poor indoor air quality, and reduced energy efficiency.
Fortunately, with the right construction strategies, design choices, and maintenance practices, moisture issues can be prevented or mitigated. In this guide, we’ll break down everything you need to know about identifying, preventing, and addressing moisture problems in barndominiums.
Why Moisture is a Big Concern for Barndominiums
Unlike traditional wood-framed homes, barndominiums often feature:
- Metal siding and roofing – which can cause condensation when indoor air meets cooler surfaces.
- Concrete slab foundations – which may wick moisture from the ground if not properly sealed.
- Large open floor plans – which can trap humidity in certain areas.
Moisture problems can show up in different ways:
- Water stains on walls or ceilings
- Mold growth on drywall, wood, or carpet
- Condensation on windows or metal surfaces
- Musty odors
- Corrosion of metal framing or siding
- Buckling floors
Left unchecked, these issues can compromise both comfort and structural integrity.
Step 1: Address Moisture at the Foundation Level
The battle against moisture starts long before move-in day—at the foundation.
Proper Site Preparation
- Grading: Ensure the land slopes away from the barndominium so rainwater doesn’t pool around the foundation.
- Drainage Systems: Install French drains or swales if your site is prone to standing water.
Foundation Sealing
- Vapor Barriers: Place a thick plastic vapor barrier (typically 6–15 mil polyethylene) beneath the concrete slab to prevent ground moisture from wicking upward.
- Waterproof Coatings: Apply a concrete sealer on top of the slab to add extra protection.
Consider Raised Foundations
In areas with frequent flooding or high groundwater, building on piers or a raised foundation can reduce moisture risks dramatically.
Step 2: Choose Moisture-Resistant Building Materials
Your choice of materials will directly influence how your barndominium handles moisture.
- Insulation: Use closed-cell spray foam or rigid foam board insulation, both of which resist moisture better than fiberglass batts.
- Wall Materials: Opt for cement board, treated wood, or moisture-resistant drywall in areas prone to dampness (bathrooms, kitchens, basements).
- Flooring: Tile, sealed concrete, and luxury vinyl plank (LVP) perform better than carpet or untreated hardwood in humid conditions.
- Roofing Underlayment: Install a moisture-resistant underlayment beneath the metal roof to prevent condensation drips.
Step 3: Control Indoor Humidity
Even with a dry foundation and good building materials, barndominiums can accumulate excess indoor humidity.
Ventilation Strategies
- Mechanical Ventilation: Use bathroom fans, range hoods, and laundry room exhausts that vent outdoors—not just into the attic.
- Attic Ventilation: Ridge vents and soffit vents help keep roof structures dry.
- Whole-House Ventilation: In high-humidity climates, an ERV (energy recovery ventilator) or HRV (heat recovery ventilator) system can regulate airflow without sacrificing efficiency.
HVAC Systems
- Dehumidifying HVAC Units: Modern HVAC systems can control both temperature and humidity.
- Standalone Dehumidifiers: Useful in basements, garages, or areas with poor airflow.
Everyday Practices
- Run exhaust fans when cooking or showering.
- Avoid drying clothes indoors without proper ventilation.
- Keep indoor humidity between 30–50% to prevent mold growth.
Step 4: Manage Condensation on Metal Surfaces
Since many barndominiums rely on metal siding and roofing, condensation control is critical.
- Insulated Panels: Insulated metal panels help reduce thermal bridging and condensation.
- Proper Insulation: Spray foam insulation applied directly to metal siding can stop warm indoor air from contacting cold metal.
- Thermal Breaks: Use wood or composite furring strips to separate metal surfaces from interior finishes.
- Roof Drip Control: Install a condensation barrier under the roof panels to prevent dripping inside the living space.
Step 5: Waterproof Problem Areas
Some areas of a barndominium are naturally more prone to moisture problems.
Bathrooms & Kitchens
- Install moisture-resistant drywall (“green board”).
- Use high-quality caulking around tubs, sinks, and backsplashes.
- Add waterproof underlayment beneath the bathroom tile.
Laundry Rooms
- Ensure dryers vent directly outside.
- Install a floor drain if possible to catch leaks.
Basements or Crawl Spaces
- Use vapor barriers on walls and floors.
- Install a sump pump in flood-prone areas.
- Keep crawl spaces well-ventilated or encapsulated with a dehumidifier.
Step 6: Regular Maintenance to Prevent Moisture Damage
Even the best-built barndominium needs regular upkeep.
- Inspect the Roof: Check for leaks, rust, or loose fasteners.
- Clean Gutters & Downspouts: Ensure water flows away from the house.
- Seal Gaps & Cracks: Prevent water intrusion around windows, doors, and siding joints.
- Check for Plumbing Leaks: Even small drips can create big moisture issues over time.
- Monitor Indoor Humidity: Use a hygrometer to keep levels in check.
Step 7: Identifying and Fixing Existing Moisture Issues
If your barndominium already has signs of moisture damage, here’s how to tackle them:
- Mold Growth: Use mold-specific cleaners and address the source of moisture immediately. Large infestations may require professional remediation.
- Condensation on Windows: Upgrade to double-pane windows or add storm windows to improve insulation.
- Musty Odors: Increase ventilation, run a dehumidifier, and clean soft surfaces like curtains or carpets.
- Water Stains on Walls/Ceilings: Trace the leak source (roof, plumbing, condensation) and repair it before repainting.
- Rust or Corrosion on Metal Surfaces: Remove rust with wire brushing, apply rust inhibitors, and repaint with a protective coating.
Climate-Specific Moisture Strategies
Moisture issues vary depending on where your barndominium is located:
- Humid Southern States: Focus on HVAC dehumidification and sealed crawl spaces.
- Cold Northern States: Prevent condensation by insulating metal surfaces and controlling indoor humidity.
- Coastal Areas: Use corrosion-resistant fasteners and marine-grade sealants.
- Dry Climates: While less prone to humidity, still watch for condensation on cool metal surfaces in winter.
Final Thoughts
Moisture issues are one of the most common—and potentially costly—challenges faced by barndominium owners. However, by addressing them from the ground up with proper site prep, high-quality building materials, good ventilation, and regular maintenance, you can protect your investment and ensure a comfortable, healthy living environment.
Think of moisture management not as a one-time task but as an ongoing system of prevention, monitoring, and response. With the right strategies in place, your barndominium can remain dry, efficient, and durable for decades to come.