wooden house

DIY Mobile Home Skirting

If you own a mobile home, skirting is an important part of your home. More than just decorative, skirting protects the underbelly of your home from critters and weather, both of which can cause damage. At the same time, it can provide valuable storage space for things that you don’t use on a daily basis. While not usually insulated, skirting provides some barrier to extreme temperatures, making it so that the home’s insulation can do a better job.

The skirting and its framework do not provide any additional structural strength to the mobile home. it is supported by their own structure, a pair of I-beams running the length of the trailer and sitting on stacks of blocks, called piers. So all the skirting’s structure needs to do is be strong enough to support the weight of the skirting itself and hold it in place through the weather and the vagrancies of life. Keep in mind though, that children will run into it with toys, so it has to be fairly strong and rigid to withstand day-to-day use.

Skirting, sometimes referred to as “underpinning” is actually a regulatory requirement, although not everyone pays attention to that regulation and it is not always enforced. But if you have purchased a home with a HUD backed loan, you must skirt your mobile home. The basic requirements are:

  • Permanent wall enclosing the foundation
  • Must be self-supporting
  • Must rest on a concrete footing
  • Must have access opening

While important, skirting doesn’t come as part of a new mobile home purchase and may not even come with a used one when you buy it. A variety of companies manufacture skirting or skirting kits, but these are expensive, especially the more attractive ones. You can do much better and save yourself a considerable amount of money by making your own. Usually, that means making them out of wood.

Ground Vapor Barriers

Before skirting a mobile home, it is important to install a ground vapor barrier. This is not the same as a “belly wrap,” which is a plastic barrier attached under the floor of the mobile home. The ground vapor barrier is a heavy plastic barrier, which rests directly on the ground, keeping ground moisture from reaching the under-flooring of the mobile home. At the same time, it serves to help keep weeds from growing, although that shouldn’t be much of a problem, with the skirting blocking out the sunlight.

Properly installed, a ground vapor barrier will extend six inches out from the dimensions of the mobile home, all the way around. This means that your skirting and the structure to support it, will actually sit on top of the ground vapor barrier. That’s good news, as it can also protect that wood from moisture in the ground.

Ventilation

Even with ground vapor barriers, it is important to provide ventilation in your home’s skirting. The basic rule of thumb is one square foot of vent, for every 150 square feet of the mobile home’s floor space. If you have a ground vapor barrier, you can use less vents, installing one square foot for every 300 square feet of floor space.

Ventilation is needed to keep moisture, specifically in the form of humidity, from accumulating underneath your mobile home. Too much humidity can result in mold growth, including forms of mold which can release spores which are harmful to your health.

Vents should be scattered, and are best placed near the corners of the mobile home. This helps ensure that there is airflow throughout the entire area underneath the mobile home and that there are no dead zones where there is no air movement.

Materials for the Skirt

There are a number of different wood products which can be used to make attractive and effective mobile home skirts. Some of the most popular are plywood, OSB (Oriented Strand Board) and T-111. There are a few important considerations when using any of these materials, as moisture can cause them to warp or become damaged.

The most important consideration is sealing the edges of each panel. This can be done with paint, but you will get a more complete seal if you use acrylic painter’s caulk. While a somewhat time-consuming process, rubbing the painter’s caulk into the grain on all the panel edges provides for a much better and thicker seal, which should last for 25 to 30 years.

You also need to paint both sides of the panels. If only the outside is painted, moisture can attack the inner side, causing the panel to warp. By painting the inside as well, you protect both surfaces from moisture. Any paint can be used for the inside, even interior paints, as it will not be exposed to ultraviolet light. However, you do want a couple of heavy coats, not leaving any thin or dry spots.

Framing Your Skirting

Building the skirting is basically a two-step process. First a framework is built and then the skin is applied. While it is possible to build panels which combine the framework and skin, and then install them in place, you will probably not get as good a finish, as invariably there will be fit problems due to unexpected irregularities in the footer or the mobile home.

Since we are making the skirting out of engineered sheet wood products, it will be necessary to provide some framing, otherwise there’s a high probability that the skirting will warp and possibly even cup. This framing should be made of 2”x 4” construction lumber. I would recommend using pressure treated 2”x 4”s for the bottom rail, but it is not necessary to use them for the verticals or the top rail.

Since the materials we are talking about using come in four foot by eight foot sheets, it makes sense to make the frame sections eight feet long. You are essentially framing it as a short wall or “stem wall”. It is not necessary to put the studs every 16 inches, but I wouldn’t put them farther than every 24 inches apart, even though some people do. You also don’t need a double top plate, like is normally used for a framed wall. That double top plate is for you to attach the upper edge of the drywall to, after installing the ceiling. Since there is no ceiling and no drywall, there is no need for the double top plate.

The individual frame sections should be attached together, attached to the underside of the mobile home’s floor framing and attached to the foundation. You don’t need to go to overkill on nailing, as all the structure has to do is stay rigid for the skirting, not provide any additional structural strength. However, you do need to attach it well enough that the wind doesn’t cause it to come loose.

Use screws, rather than nails, to attach the framework, as screws are easier to remove, if you ever end up needing to move your home. Even if you don’t move it, screws allow you to go back at a later time and retighten them, should they start loosening as the wood dries out.

You may want to consider adding a layer of Styrofoam insulation behind your skirting. This is not required and only makes a minimal difference; but as most mobile homes offer little in the way of insulation under the floor, so adding this layer of insulation will help keep the floors from getting quite so cold in the wintertime. The Styrofoam will pay for itself in what it saves you on heating costs.

Finally, the skin panels can be cut and installed. I would recommend staggering the skin pieces, rather than aligning the seams with the framework. In this way, the seams for the skin will be halfway down the length of the frame, adding additional structural strength. However, if you expect to be moving your mobile home at any time, attaching the skin so that it is aligned with the ends of frame sections would make it easier to remove the skirting and transport it to the new site.

Don’t forget to seal all the edges and paint the skirting well, so as to seal it and prevent it from becoming water damaged. A couple of coats with a good acrylic-latex paint will work, but it would be even better if you sealed the skirt with a high-quality sealing primer first.

wooden house
Wooden house, Kevin Poh

Alternative Framing

There is an alternative to framing a stem wall; that’s to install only a bottom rail and use the floor joists of the mobile home as your top rail for installing the wood siding. Some mobile home designs, especially older ones, allow for this, in having the siding set into a Z-rail, four to eight inches above the bottom of the mobile home. The area below the Z-rail can be used as to attach the skirting too. However, you may need to remove a horizontal trim piece to allow this.

In this case, you’ll need to drive stakes into the ground, to attach the bottom rail to. To locate these stakes, use 2”x 4”s, aligning them flush with the side of the mobile home and running all the way down to the ground. The stakes should be set back just far enough from where these 2”x4”s come down, to leave room for a 2”x 4” or 1”x 4” bottom rail.

Keep in mind that this type of framing won’t be as strong. You definitely don’t want to try nailing your skin to the bottom rail. It’s better to use screws. Driving nails into the bottom rail would pull the stakes loose.

Various Wood Designs

What we’ve talked about so far is simple skirting, which is nothing more than plywood or other engineered wood panels. You may want to consider some other options, instead of this style.

One is to use strips of wood, like 1”x 4”s to make rails around the perimeter as your skirt, rather using OSB or T-111 to provide a solid skin. This provides a more rustic look, something like a split-rail fence. These strips can be painted or stained, either to match the mobile home or to accentuate the idea of them looking like a fence.

If you really need to save money, you can make something that looks just about like what I just described, by cutting pallets and attaching them together to form a skirt. The combination of slats and open spaces will give the same effect of being a fence.

Lattice board can make a nice skirt as well. However, you don’t want to use a lattice board by itself. Rather, cut the pieces of lattice board and frame them with 1”x 4”s to make skirt panels. These can then be attached to your framework. Painting the lattice one color, with the 1”x 4” frames another color can add a nice visual effect.

House Skirting Panels

There are a variety of different skirting panels available on the market, many of which are molded plastic, which can provide a different look for your mobile home underpinning. These can vary considerably, from looks like faux stone to vinyl siding.

These plastic panels usually come as part of a kit, with their own installation methods. However, they are considerably weaker than a wood skirt. A compromise installation is possible, where the decorative plastic panels are installed over a wood skirting, made of one of the materials mentioned earlier or just of construction-grade plywood.

Skirting a Shed

The same types of skirting which are used for mobile homes will work just as well for a shed, whether one you have made yourself or a purchased one. Many sheds are made with a post and beam construction, rather than a concrete slab, making them similar in construction to a mobile home. This makes it easy to adapt the skirting materials and techniques used for mobile homes, to these sheds.

If you happen to have both a mobile home and a shed, you can skirt them alike, making them match. In the case of using skirting panels, it is recommended to buy all of them at the same time, so as to ensure that colors and styles match.

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