Insulating Skirting on a Mobile Home
Insulating the skirting around a manufactured or mobile home is one of the most effective winterization projects a homeowner can undertake. Uninsulated crawlspaces allow biting winter winds to sweep underneath the floor, freezing water supply pipes, chilling subfloors, and causing home heating systems to run constantly. Discover how to properly insulate mobile home skirting to lower utility bills and prevent frozen plumbing lines.
Skirting Insulation Materials and Performance
Manufactured homes are elevated on concrete piers or steel chassis, creating a large, open underbelly cavity exposed to freezing outdoor winds. While standard vinyl or aluminum skirting provides a decorative visual barrier and keeps out wildlife, thin hollow panels offer virtually zero thermal R-value against sub-freezing temperatures.
Insulating skirting requires understanding the delicate balance between thermal retention and crawlspace moisture management. Sealing under-home drafts while preventing summer ground moisture condensation ensures your plumbing stays thawed and your subfloor framing remains rot-free.
Compare the primary insulation products used behind mobile home skirting panels:
| Insulation Material | R-Value per Inch | Estimated Cost / Lin Ft | Moisture Resistance | Rodent / Wildlife Resistance |
|---|---|---|---|---|
| Expanded Polystyrene (EPS Foam Board) | R-3.8 to R-4.0 | $1.50 to $2.50 | Good (Moisture resistant; needs ground clearance) | Moderate (Requires protective backing) |
| Extruded Polystyrene (XPS Pink/Blue) | R-5.0 | $2.20 to $3.50 | Exceptional (Can be buried directly in soil) | High (Dense closed-cell structure) |
| Polyisocyanurate (Foil-Faced Polyiso) | R-6.0 to R-6.5 | $3.00 to $4.50 | High (Foil acts as radiant heat reflector) | High (Foil faces deter pests) |
| Insulated Concrete Skirting (K-Rock / Novik) | R-8.0 to R-12.0 | $12.00 to $22.00 | Impervious to rot, water, and weed trimmers | Exceptional (Simulated rock/brick barrier) |
| Fiberglass Batts (NEVER on skirting) | R-3.2 | Low ($0.80) | TERRIBLE (Acts like a sponge, rots, attracts mice) | POOR (Nesting material for rodents) |
Thermal Impact and Winter Energy Savings
The single most effective material for insulating mobile home skirting is rigid Extruded Polystyrene (XPS) foam board, commonly recognizable by its pink or blue color. Unlike fiberglass batts—which must never be placed in a damp ground-level crawlspace where they absorb moisture and attract rodent nesting—XPS foam is an impervious closed-cell material that can be buried directly in the earth to block ground drafts.
Begin by installing a continuous 6-mil polyethylene ground vapor barrier across 100% of the crawlspace soil before insulating the perimeter walls. Earth naturally evaporates gallons of ground water vapor daily into the enclosed space. Covering the soil with heavy plastic, overlapping seams by 12 inches, and weighting the edges down with sandbags stops ground moisture from rising and condensing on wooden subfloor floor joists.
Analyze the temperature and financial benefits of adding insulated rigid foam skirting:
| Crawlspace Configuration | Outdoor Temp: 10°F | Crawlspace Temp Range | Pipe Freeze Risk | Monthly Heating Energy Cost |
|---|---|---|---|---|
| Unskirted / Open Piers | 10°F | 12°F to 15°F | Catastrophic (Pipes burst within hours) | Extremely High ($350 - $450+) |
| Standard Thin Vinyl Skirting | 10°F | 18°F to 24°F | High (Pipes freeze on windy nights) | High ($280 - $350) |
| Vinyl Skirting + 1.5" XPS Foam Board | 10°F | 36°F to 42°F (Above freezing) | Extremely Low (Heat loss from floor warms air) | Moderate ($180 - $240) |
| Engineered Insulated Skirting Panel | 10°F | 40°F to 48°F | Near Zero (Stable thermal envelope) | Optimized ($140 - $190) |
Strategic Guidance and Expert Recommendations
When attaching 1.5-inch or 2-inch XPS foam boards to the interior side of your existing vinyl skirting, dig a shallow four- to six-inch trench along the ground perimeter. Set the bottom edge of the foam boards into the trench and backfill with gravel or soil. This "trenching" stops winter gales from blowing underneath the bottom track of the skirting.
Carefully manage crawlspace ventilation. During harsh winter months, many northern homeowners seal foundation vents to trap radiant floor warmth and prevent pipe freezes. However, you must reopen foundation vents in the spring and summer to allow cross-ventilation, or install temperature-controlled automatic foundation vents that open when temperatures exceed 40°F and close when freezing weather approaches.
How to Insulate Mobile Home Skirting Step by Step
Follow this practical step-by-step guide to install rigid foam board insulation behind mobile home skirting.
Lay a Heavy-Duty Ground Vapor Barrier
Spread 6-mil black polyethylene sheeting across the entire crawlspace dirt floor, overlapping seams by 12 inches and weighting down with bricks or gravel.
Dig a Perimeter Ground Trench Along Skirting
Excavate a shallow trench 4 to 6 inches deep directly behind the bottom channel track of the mobile home skirting.
Cut and Position 1.5-Inch or 2-Inch XPS Foam Boards
Measure the height from the bottom of the home rim joist into the trench; cut rigid foam sheets to size using a utility knife.
Fasten Foam Boards to Wood Framing or Skirting
Secure the foam boards to interior 2x2 wood nailer studs using exterior-rated washer screws, or bond directly to vinyl backing with foam-compatible adhesive.
Seal Seams with Vapor Tape and Backfill Trench
Tape all vertical foam joints with weather-rated foil tape, and backfill the exterior trench with dirt or crushed gravel to lock out drafts.
Frequently Asked Questions (7 Questions Answered)
Q1: Can you use fiberglass insulation behind mobile home skirting?
No, never use fiberglass batts behind skirting; fiberglass absorbs ground moisture like a sponge, loses all insulating value, develops toxic mold, and attracts mice.
Q2: What is the best insulation for mobile home skirting?
Extruded Polystyrene (XPS) rigid foam board (1.5" to 2" thick) is the best choice because it resists moisture, can be buried in dirt, and offers R-5 to R-10 thermal protection.
Q3: Should mobile home skirting vents be closed in winter?
In freezing winter climates, many homeowners close vents to keep the crawlspace above freezing and prevent pipe bursts, but vents must be opened in spring to prevent mold.
Q4: Does insulating skirting really prevent frozen pipes?
Yes, insulated skirting blocks freezing wind drafts and traps natural radiant heat loss from the home floor, keeping the crawlspace 15° to 25° warmer than outdoor temperatures.
Q5: How do you keep rodents from chewing through foam skirting?
Install heavy-gauge 1/4-inch galvanized steel hardware cloth (wire mesh) along the base of the skirting, burying it 6 inches into the earth to block burrowing animals.
Q6: How much does it cost to insulate mobile home skirting?
Insulating an average single-wide or double-wide home with 1.5-inch XPS foam boards typically costs between $400 and $900 in materials for a DIY project.
Q7: Can you put hay bales around mobile home skirting?
While hay bales are a traditional emergency fix, they are a severe fire hazard, decompose rapidly, and attract thousands of mice and insects near your home.
Final Thoughts & Key Takeaways
In conclusion, understanding insulating skirting on a mobile home provides essential clarity, practical strategies, and actionable advice. By incorporating these foundational insights, adhering to verified safety guidelines, and following structured best practices, you ensure reliable, long-term outcomes while preventing common mistakes. Stay informed, consult certified professionals when needed, and maintain consistent quality care.