Tiny House Sheathing
Sheathing is a critical component in tiny house construction that provides structural integrity, weather protection, and insulation support. Whether you’re building a tiny house on wheels or a stationary small dwelling, understanding sheathing options and proper installation techniques is essential for a durable and energy-efficient home.
What is Tiny House Sheathing?
Sheathing refers to the material layer that covers the exterior frame of your tiny house. This layer serves multiple purposes:
1. Adds structural rigidity to the frame
2. Creates a base for attaching exterior siding
3. Provides a barrier against moisture and weather
4. Contributes to the overall insulation system
5. Helps distribute loads across the structure
For tiny houses, proper sheathing is particularly important due to the compact nature of the structure and the potential mobility of tiny houses on wheels.
Common Sheathing Materials for Tiny Houses
Plywood Sheathing
Plywood is one of the most common sheathing materials used in tiny house construction. It offers excellent structural support and comes in various thicknesses. For tiny houses, 3/8″ to 1/2″ plywood is typically used for wall sheathing, while roof sheathing may require 1/2″ to 5/8″ for adequate support.
Plywood provides good nail and screw holding power, which is particularly important for tiny houses on wheels that will experience movement and vibration during transport.
OSB (Oriented Strand Board)
OSB is another popular option for tiny house sheathing. It’s generally less expensive than plywood while offering similar structural properties. OSB is made from compressed wood strands and resin, creating a strong panel that resists delamination.
For tiny houses, OSB can be a cost-effective alternative to plywood, though it may be slightly more susceptible to moisture damage if not properly protected.
Specialty Sheathing Products
Some builders opt for specialty sheathing products that combine multiple functions. For example, some products come with house wrap or roof felt already attached, streamlining the construction process. These integrated systems often have interlocking edges or “nubs” that help with alignment and create a tighter seal between panels.
Foam Board Sheathing
Rigid foam insulation boards can also serve as sheathing in tiny houses. These provide the dual benefit of structural support and insulation in one layer, which can be valuable in space-constrained tiny house walls. Common types include:
– Polyisocyanurate (polyiso)
– Extruded polystyrene (XPS)
– Expanded polystyrene (EPS)
When using foam board sheathing, it’s often necessary to use plywood at corners and other key structural points to ensure adequate strength.
Sheathing Installation for Tiny Houses
Wall Sheathing
When installing wall sheathing on a tiny house:
1. Start at a corner and work your way around the structure
2. Ensure panels are oriented correctly (especially important for OSB which has a specific strong direction)
3. Leave a small gap (1/8″) between panels to allow for expansion
4. Stagger joints to increase structural integrity
5. Use appropriate fasteners – typically screws or ring-shank nails
6. For tiny houses on wheels, fasteners should be spaced more closely (4-6″ on center) than in traditional construction to account for road vibration
Roof Sheathing
Roof sheathing requires special attention in tiny houses:
1. Use thicker sheathing material (minimum 1/2″) for adequate support
2. Install from the bottom edge working upward
3. Stagger joints between rows
4. Ensure proper overlap at ridge points
5. Leave appropriate spacing for expansion (typically 1/8″)
6. Use H-clips between panels if specified by your building plans
Fastener Considerations
The choice and placement of fasteners is crucial for tiny house sheathing, especially for mobile builds:
1. Use screws rather than nails when possible for better holding power
2. Space fasteners 4-6″ on center along panel edges
3. Space fasteners 6-12″ on center in the field (middle area) of panels
4. Be careful not to overdrive fasteners, which can reduce holding strength
5. For 3/8″ plywood, use extra care to prevent overdriving
Weather Protection for Tiny House Sheathing
House Wrap and Moisture Barriers
After installing sheathing, applying a proper moisture barrier is critical:
1. Install house wrap over wall sheathing, starting from the bottom and working up
2. Overlap seams by at least 6 inches
3. Tape all seams with appropriate house wrap tape
4. Pay special attention to openings like windows and doors
5. For roofs, use appropriate roofing felt or synthetic underlayment
Some tiny house builders opt to use just house wrap without sheathing in non-structural areas to save weight, but this approach sacrifices structural integrity and is generally not recommended for the entire structure.
Integrated Sheathing Systems
Some modern sheathing products come with integrated weather barriers, which can simplify the construction process. These products typically feature:
1. Pre-attached house wrap or weather-resistant coating
2. Special edge treatments to create tighter seals
3. Printed guidelines for fastener placement
4. Reduced installation time compared to separate systems
Special Considerations for Tiny Houses on Wheels
Tiny houses that will be transported require extra attention to sheathing details:
1. Use slightly thicker sheathing than might be used in stationary construction
2. Install additional fasteners, especially along edges and corners
3. Consider using construction adhesive in addition to mechanical fasteners
4. Pay special attention to sheathing around windows and doors, as these are stress points during transport
5. Consider diagonal metal strapping over sheathing at corners for added strength
Combining Sheathing with Insulation
In tiny houses, where wall thickness is limited, efficient use of space is crucial:
1. Consider using rigid foam sheathing in combination with traditional sheathing for added R-value
2. When using foam board sheathing, ensure structural requirements are still met
3. For traditional sheathing, plan for adequate cavity space for insulation
4. Consider advanced framing techniques that allow for more insulation and less thermal bridging
Conclusion
Proper sheathing is a fundamental aspect of tiny house construction that affects structural integrity, weather resistance, and energy efficiency. Whether you choose plywood, OSB, foam board, or specialty products, ensuring correct installation with appropriate fasteners and weather barriers will result in a durable, comfortable tiny home.
For tiny houses on wheels, the additional considerations of weight and road vibration make sheathing choices and installation methods even more critical. Taking the time to properly research and install your tiny house sheathing will pay dividends in the longevity and performance of your small dwelling.