Manufactured Home Vapor Barrier Options: Are They Necessary?

Moisture issues are hardly uncommon in manufactured homes. Whether it is humidity or crawl space moisture, you will merely like it. Regardless, they do not spell doom for you, as long as you understand how to handle them. That implies that we should first try to understand what each problem presents to us. Here are a few insights.

Crawl space moisture issues involve excess water within your crawl space. It will happen regardless of whether there is enough ventilation or not. Usually, once the air seeps into this space, it cools off, which increases humidity. This humidity could rise to a level where condensation becomes inevitable.

On the other hand, a rise in humidity within the home could also be a problem. It will arise when you do not regulate the internal temperatures of your home correctly. Some of the things that could lead to this change include basics such as cooking, bathing, and other activities that could contribute to steaming. This condensation makes the home vulnerable to molds and stains.

Fortunately, it is at this point that vapor barriers come in. We can all agree that most people are doubtful of whether to install these barriers in their manufactured homes or not. The simple answer to this concern will be, you need to install this vapor barrier. But is it important? How do you install and what are the manufactured home vapor options? Join us as we explore these basics.

Do you need a vapor barrier in your manufactured home?

Vapor barriers are thin, film-like materials that deter the diffusion of water vapor into various surfaces. As mentioned, having a vapor barrier will be one of the best decisions you could ever make for your manufactured home. We could attribute this to the role it will play in maintaining the structural integrity of your home. You will also rely on them in protecting your insulation too.

This barrier will come in handy in ensuring that water drains away from home, and instantly so. You will hardly ignore how it matters in protecting the walls, attics, floors, and ceilings from moisture. They will also help safeguard crawlspaces against water as well.

As long as your home is on the moist ground or standing water, it will be vulnerable to the accumulation of water vapor. As this vapor rises within the house, there will be an increase in molds and stains. Unless you have a credible barrier, this problem will worsen with time.

Mostly, these vapor barriers will be ideal for people within cold climates.

If you live in a freezing place, you will need either Class I or II (which we shall discuss shortly) types of vapor barriers.

You will also need to consider this barrier if you want to add an exterior wall to your manufactured home. That is because these new walls might result in air leakages, which will increase the moisture in the house.

On top of that, the cladding type of your house will always matter. If your home comes with moisture-retaining claddings, you will have to make vapor barriers a priority. Such coatings usually escalate inward vapor, as they release moisture into the structure.

Three Manufactured Home Vapor Barrier Options

Various types of vapor barriers are at your disposal. These barriers could be either Type 1, 2, or Type 3. Your choice will be dependent on your needs, budget, and even preferences. Ideally, the type of barrier you choose depends on the material it is made from. Some of the top choices you will get include the following.

Class I Vapor Barriers

Class 1 vapor barriers will often come with a permeance of less than 0.1. That implies that the amount of moisture allowed through these barriers will hardly go over 0.1 perms.

Some of the materials that offer you this level of reliability will include glass, sheet metal, rubber membrane, and polyethylene sheet.

Class II vapor barriers

These vapor barriers pride themselves on permeance of more than 0.1 but less than one perm. While they might not be as reliable as class I barriers, they assure you of relatively enhanced credibility. Some of the top barriers you might want to consider under this category are like asphalt-backed kraft paper, unfaced expanded polystyrene, and asphalt-coated paper.

Class III vapor barriers

While this third class of vapor barriers might offer the highest permeance, you will still find them reasonably reliable. They assure you of permeance of approximately one but less than ten perms. Materials that provide you with this level of permeance include cellulose insulation, board lumber, fiberglass insulation, and gypsum board.

If you can afford, let Class I barriers be your priority. That is because they will provide you with enhanced durability, least permeance, and value for your money. Their restrictive moisture transmission implies that you will enjoy better structural integrity in the long run.

How to install vapor barriers

Indeed, manufactured homes are exposed to various elements, primarily through their underbelly. For this reason, insulating the house will be ideal. That should be coupled up with a properly installed vapor barrier.

Did you know that if you do not install your vapor barriers properly, you will only make yourself more vulnerable? First, it will be necessary to point out that you have to fix these vapor barriers before you insulate your building. Ensure that you follow the following procedure once you do so.

Lay your barrier down

Ensure that you put a moisture barrier at the belly of your manufactured home before you start insulation. Preferably, let your insulation be a product of plastic sheeting.

Most experts recommend that the plastic be at least six inches up the wall.

This way, you will be confident of no moisture infiltrating your insulation. Besides, it will enhance comfort when crawling.

Take the time to pry off the barrier beneath the manufactured house using the right tools. Remember to leave only one side of this barrier attached to the rim. While at it, you will have to cover all your water pipes with foam insulation.

Inspect seams

Take the time to inspect the layers between the joists and the floor. You will also need to verify the different points at which wires and pipes pass through this floor. Such will be the time to fill any gaps with silicone caulk. While a few holes on these seams might not affect the performance significantly, it will be vital to aim at minimizing them.

While at it, you will need to fill all cavities in the joists that have fiberglass insulation. Paper-backed insulation will always come in handier at this point. Ensure that you staple them together such that there are minimal chances of leakage.


Indeed, every home will often have various hard-to-reach places. Take the time to insulate these spots with polyurethane foam insulation. Ideally, it would be best if you focused on each vulnerable area of your home’s foundation. Preferably, this insulation should be at least one and a half inches thick.

From here, you will move to insulate the rim joists. It will help in reducing air leaks in the long run. Once you are through with that, cap the interior walls with a 6 ml layer of plastic. With this, you will be confident of protecting your home against termite attacks too.

Precautions when installing vapor barriers

Various building experts suggest that you be careful when installing these vapor barriers. This move aims at ensuring that you enjoy the safety and comfort that you so deserve.

Usually, they recommend that you stick by the following principles at all times:

  •  Avoid installing vapor barriers on both sides of your building’s claddings. It is through this that you will be sure of proper drying in at least one side
  •  Shy away from installing vapor barriers that come with a radiant appeal, as they could make your building moldy in the long run
  • If your house is air-conditioned, ensure that you do not install vinyl wall coverings
  •  Only use vapor barriers if vapor retarders cannot assure you of optimal results

Benefits of installing vapor barriers

Various advantages come with having reliable vapor barriers in your manufactured home. Some of the top merits will always include the following.

  • It will increase energy efficiency within your building
  • Vapor barriers cushion you against musty odors and moldy environments
  • It will be easier to maintain an optimal temperature within the house
  • The integrity of the crawl space pipes will remain matchless

Final Verdict

In conclusion, vapor barriers will always be vital for anyone who needs enhanced comfort. As long as you install them accordingly, you will be sure of the best results in the long run. Feel free to consult experts for better results.