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The space under a manufactured home is warm, dry, sheltered and lined with insulation. Animals under mobile home floors are not a sign that something is wrong with your house. They are a sign that it is the most attractive real estate on the block.
The fix is exclusion, done in a specific way, at a specific time of year. Everything else on the shelf at the hardware store is a waste of money, and the university extension services have said so repeatedly.
Animals under mobile home floors: what gets in, and what it does
Skunks dig shallow burrows under structures. The smell is the least of it.
Opossums are not strong and do not force entry — they use gaps that already exist. What makes them a manufactured housing problem specifically is where they go next: extension literature documents opossums climbing into the insulation under the floor and moving about the ductwork of mobile homes. That is your crossover duct.
Raccoons actively enlarge openings and need only a 4-inch gap.
Rats and mice chew wiring and insulation, which is the reason exclusion mesh is specified by gauge rather than by eye.
Feral cats shelter and breed in crawl spaces, and are enough of a fixture in manufactured housing communities that there is published guidance written specifically for parks.
Snakes follow the rodents.
The damage list under a manufactured home is worse than under a house, because the systems down there are exposed: the belly wrap, the floor insulation inside it, the crossover duct, and the plumbing.
The mesh, and the apron
Hardware cloth. The sizes come from extension-service wildlife damage literature, and they are specific:
| Target | Mesh | Gauge |
|---|---|---|
| Rats | ½ × ½ inch | 19 |
| Mice | ¼ × ¼ inch | 24 |
| Snakes | ¼ inch | — |
| Skunks and larger | ½ inch weave | — |
The burial detail is the part that matters. For skunks, the wildlife damage management guidance specifies burying the mesh 2 inches below ground and extending it outward, perpendicular to the structure, at least 12 inches — an L-shaped apron rather than a deeper vertical barrier. Montana State Extension’s version buries the lowest foot with the bottom 6 inches bent outward.
For rodents, the barrier should reach 36 inches below grade, or, if that is not practical, carry a horizontal ledge extending outward at least a foot. For snakes, ¼-inch mesh buried about 6 inches, and every gap larger than ¼ inch sealed.
The logic of the outward apron is that a digging animal works down the face of the barrier and hits a horizontal shelf before it can get under. It is worth being straight about this: the extension sources show the apron in their diagrams but none of them presents it as a tested comparison against straight burial. It is the standard detail rather than a proven one.
One gap in the literature: nobody publishes how to fasten hardware cloth to vinyl or metal skirting panels. That is an installer detail, and it will depend on what your skirting is made of.
You cannot just seal everything
This is where manufactured homes differ from houses, and where a lot of well-meaning advice goes wrong.
24 CFR 3285.505 requires ventilation under the home, in a ratio that depends on whether you have a ground vapor barrier: one square foot of net free opening per 150 square feet of floor area, dropping to one per 1,500 if a 6-mil vapor barrier covers the ground. Openings go as high as practicable, on at least two opposite sides.
And then the same section answers the animal question directly. Those openings must have a perforated corrosion- and weather-resistant covering designed to prevent rodent entry.
So the code already tells you the correct approach: the vents stay, and they get screened. Blocking them trades an animal problem for a moisture problem, and the moisture problem rots your floor.
The access opening, incidentally, has a minimum size too — 18 inches wide by 24 inches high, at least 3 square feet.
Get them out before you seal, and mind the month
Sealing the perimeter with an animal underneath produces either a dead animal in your crawl space or a determined one chewing its way out through your belly wrap.
The method is a one-way door: minimum 4 by 4 inches, fitted over the active entrance so the animal can leave and cannot return. Leave it three to five days after activity stops, then seal permanently.
The timing is not optional. Montana State Extension gives the months for skunks: burrows sealed from early May to mid-August may leave young trapped in the den. Older females give birth in May, yearlings in June. Seal in that window and you have sealed in a litter.
What does not work
University extension services have tested the shelf remedies and published the results.
Mothballs are a registered pesticide, and using them outdoors as a repellent is unlawful off-label use. UF/IFAS notes separately that they are far less effective outdoors anyway, because the odour cannot concentrate.
Ultrasonic and vibration repellents are, in UGA Extension’s words, “widely believed to be useless… tested and show no impact on the target species,” and “almost completely useless” for rats, mice and snakes. UF/IFAS files them under control methods not recommended.
Ammonia we could find no university source on, either way.
Before you trap anything
Trapping and relocation is regulated at state level and frequently illegal without a permit.
Purdue Extension’s guidance for Indiana: relocation requires written landowner permission and must happen within the county of capture; furbearers such as raccoons and skunks require a state DNR nuisance control permit outside the hunting season; most migratory birds need a federal permit. California generally requires trapped animals to be released on site.
Call your state wildlife agency before you buy a trap, not after.
What it costs
Hardware cloth runs roughly $0.50 to $1.50 per square foot depending on gauge and mesh. Nobody publishes a turnkey figure for a single-wide perimeter, because it depends on your skirting height and the length of the home.
Professional work is quoted per item rather than per house: sealing gaps around pipes and vents $50 to $200 each, reinforcing crawl space vents $100 to $300 per location, with whole wildlife removal jobs commonly landing between $200 and $1,500.
Common questions
Something is under there now. What first?
Identify it, check the season, fit a one-way door, then exclude. In that order.
Will filling the gap with expanding foam work?
No. Rodents chew through it and larger animals push it out.
Do I need to screen the vents if I install hardware cloth around the skirting?
Yes. The vents are openings in the barrier. The code requires them to be covered with rodent-resistant perforated material regardless.