Mobile Home Skirting: What It Does and How to Get It Right

Mobile home skirting encloses the open space between the bottom of a manufactured home and the ground. Done right, it blocks wind from running under the floor, keeps the belly plumbing out of moving cold air, shuts animals out, and stays vented so ground moisture can leave instead of rotting the floor from below. Done wrong, it traps damp air and buckles the first hard winter.

• Skirting is a wind and pest barrier, not insulation, and not freeze protection on its own.
• Bare ground gives off water vapor all year, so vents and a sealed ground cover both belong in the plan.
• Panels should hang from a top rail and float in a bottom track so frozen ground can lift without cracking anything.
• Every home needs at least one access opening big enough for an adult and a tool bag.
• Grade and downspouts matter as much as the panels; water running toward the home ends up under it.

What does mobile home skirting actually do?

It handles four jobs, and only one of them is appearance. Wind is the one most owners underestimate. An open crawl space lets cold air run across the underside of the floor all winter and pull heat out of the belly wrap and the ductwork, and no furnace wins that fight.

Plumbing protection follows from that. In a manufactured home the supply lines and drains run through the belly rather than interior walls, so they sit in whatever air is under there, and still air is far easier on them than a crosswind at ten degrees. Heat tape and pipe insulation are what keep lines open in a cold snap; skirting keeps the wind from defeating them.

Animals are the quiet job. Skunks, groundhogs, stray cats, and mice all treat an open crawl space as shelter, and mice go straight for the belly wrap. Once it is torn, insulation sags out and the pipes hang in the weather. The fourth job is the one people get backwards: skirting has to manage moisture rather than seal it in.

Why does skirting have to be vented?

Because the ground under the home gives off water vapor every day of the year, and if it cannot get out it lands on the belly wrap, the ductwork, and the underside of the subfloor. Manufactured homes commonly have a particle board or OSB subfloor, which swells and then crumbles under steady humidity. The damage is slow and quiet, so it usually turns up during unrelated mobile home repair or when the floor goes soft by the tub.

Two measures handle it together. The first is a ground cover: sheet polyethylene over the soil, seams lapped, weighted so it stays put. Most of the moisture then never reaches the air. The second is venting, so whatever does get in has a way out. The federal manufactured home installation standard and most sets of manufacturer instructions put the figure at roughly one square foot of net free vent area per 150 square feet of under-floor area, with a large reduction commonly allowed where a proper ground cover is down. Your home's paperwork and the local code official settle what applies to your install.

Placement matters as much as the count. Spread vents around the full perimeter and near the corners so air can cross the space, because vents on one wall and nothing on the other three leave dead air, and dead air is where rot starts. If there is standing water or a cellar smell under the home now, deal with that first. Closing wet framing in turns a skirting job into water damage work.

Which skirting material makes sense?

The choice comes down to how much abuse the panels will take and whether you want insulation at the perimeter.

Insulated panels usually earn their keep in central Pennsylvania, since the perimeter is where cold air gets at the floor. The install still matters more than the material: tidy cement board with no vents and no access panel is worse than plain vinyl done right.

Where should the access panel go?

Near the water shutoff, sized so a grown person can crawl through, and never screwed permanently shut. A long home is easier to service with two openings, one toward each end, so nobody crawls the length of the floor in the dark to reach a leaking fitting. Skip it and somebody will make their own; a plumber at eleven at night will cut a hole rather than admire the panel work. Keep shrubs and the condenser pad clear of it, and if a wheelchair ramp or porch is going in along that wall, locate the access before the framing goes up.

Why does skirting buckle or pop loose in winter?

Frost heave, almost every time. Water in the soil expands as it freezes and lifts the ground with it, over and over from December into March. Skirting fastened rigidly at the top and pinned at the bottom has nowhere to put that movement, so panels bow, seams open, and the top rail gets shoved off the home.

The track system is the fix. Panels hang from a rail fastened to the home and drop into a bottom channel set at grade rather than anchored deep, cut short enough to slide vertically. When the ground rises the panel moves in the channel instead of levering against the wall, and when the soil settles everything drops back. Skirting locked into a poured curb, or buried several inches in soil, fails here for that reason. Anything tied rigidly to both the home and the ground has to reach below frost depth, which commonly runs 36 inches or more in Pennsylvania and varies by region; the local code office has the number.

Drainage is the other half. Water standing along the wall makes the worst heave of all, so grade soil to fall away from the home and run downspouts past the skirting line.

Common questions

Does mobile home skirting have to be vented?

In nearly all cases, yes. Ventilation of the enclosed space is called for in the federal manufactured home installation standard and generally in the instructions that came with the home, and it is a step that often gets skipped on a do-it-yourself install. The local code official has the final say.

Should the vents be closed for winter?

Not as a general practice. Sealing every vent traps the moisture the ground gives off all winter, and the cold months are when that vapor condenses hardest under the floor. A sealed crawl space in February is a wet one in April. For a warmer floor, insulated panels and a sealed ground cover do more than closed vents.

Will skirting keep water lines from freezing?

It helps a great deal, but it is not freeze protection by itself. Skirting stops the wind, which is most of the battle. The lines still want insulation and usually heat tape through a central Pennsylvania winter, and the belly wrap has to be intact.

How do you keep animals from digging under skirting?

Extend a barrier below grade. Galvanized hardware cloth fastened to the bottom rail and either buried a few inches down or bent outward into an L under shallow soil stops most diggers, since an animal digs at the base of a wall and hits the horizontal leg. Keep vents screened.

Does new skirting need a permit?

That depends on the municipality. Skirting alone often falls outside permit requirements, but rules vary by township and borough, and manufactured home communities frequently have standards of their own, so call the local code office before work starts. Contractors doing home improvement work in Pennsylvania are generally required to be registered under the state's Home Improvement Consumer Protection Act, and the PA HIC registration number belongs on the contract. See permit rules in Clinton County for how local approvals tend to work.