Why Do Mobile Home Windows And Walls Sweat?

Of course, water is the ultimate cause of all types of ‘sweat’ manifesting on walls, windows, skirting, etc. in homes.

Mobile homes are slightly more prone to sweating than a traditional home, and it almost always occurs on walls and windows.

But, Why Do Mobile Home Windows And Walls Sweat?

It’s hard to know, considering that causative factors in traditional homes are often different from those in mobile homes.

Phew! HUD looked it up for us

We’re lucky that HUD and Mobile Housing Research Alliance looked into the topic, eventually releasing several eBooks and bound books out there for homeowners to consult 

We’ll draw a few insights from those findings.

So, why do walls and windows sweat?

According to HUD, this problem can arise from:

  • How the home was designed and constructed
  • How it was set up
  • How it’s being operated

1. Design and Construction-related Problems

Moisture prevention starts on the drawing board.

Region-specific factors such as climate can have an impact on how your home deals with moisture.

This probably helps explain why homes in the southeast are prone to moisture penetration (Florida being the worst) than those in the northwest (Washington being the least).

Therefore, during design, both interior and exterior sources of water need to be factored in.

Use Ceiling Penetrators with Care

Be extra careful with ceiling penetrators, especially during the installation of lights, vents, and intricate ceiling designs you may choose to have.

If they don’t seal tightly enough, they may readily permit water into the home than any other part.

Hot air as well – if it’s allowed into the home via the openings in the ceiling, it may thaw the snow and cause moisture to seep into unwanted places.

In warm, humid climates, wall insulation often has two sides – the cool side and the warm side.

It’s recommended that you don’t place your vapor reducer on the cool side.


The moisture moving into wall cavities may settle, ending up trapped there.

Watch Out How You Install Your Insulation

There are two don’ts when adding a layer of insulation –


Otherwise, you will create cold areas in the wall that might be more apparent during the winter, giving rise to mold and mildew.

This is more likely to occur in corners and top plates of the home as well as during the installation of wall electrical outlets.

Reduce The Chances of Air Leakage in Walls

For every penetrator, you use, accompany it with a tight seal.

Also, use the right exterior vapor reducer.

Otherwise, air may find an opportunity to move freely in the wall and mess up its thermal efficiency, create a cold spot, and allow moisture to move around.

Position Your Air Duct Supplies and Return Ducts Appropriately

One of the easiest ways to create cold spots and cause the walls/windows to sweat is to block your air supplies or return registers.

Use the right size of registers and position them away from such obstacles as furniture and drapes.

Also, don’t install them too close to a source of water because, in the event of a leakage, blowing air may distribute moisture into the wall or floor.

Seal Your Ducts Tightly Enough

All ducts, whether they carry conditioned air or water, should be sealed tightly enough.

Badly sealed ducts may leak the condoned air and eject moisture in the wall, causing it to sweat.

2. How The Home Was Set Up

The home leaves the factory as a near-flawless piece, but how you set it up at the site of your choice may impact how it will stand up against moisture.

The installation crew may consist of both professionals and unskilled individuals.

If the crew does a shoddy job, the comfort, moisture resistance, and even energy efficiency will be affected.

State of The Ground

Grade the site properly so that the ground can drain the water. If you install your home on wet ground, the moisture may seep into the home, causing the walls and windows to sweat.

Ensure The Marriage Line Is Sealed Perfectly

Moisture may seep up from the ground past the marriage line into the home unless you seal it well with a water-tight gasket.

Cover The Ground

You can reduce moisture encroachment even further by covering the ground under the crawlspace with polythene paper.

Also, reduce the amount of debris on the ground especially if you feel it might end up coming into contact with the underbelly.

Seal Your AC Ductwork

The ductwork that serves your air conditioner should be sealed properly to prevent the conditioned air from seeping on surfaces and establishing cold spots.

The exhaust ducts serving your dryer should be kept airtight as well.

3. Moisture Issues Arising from Day-to-day Operations

Some of your daily routines may be releasing significant moisture in the air.

If the moisture doesn’t find a way out, it will certainly settle on walls and other surfaces and even cause mold to grow.

Remove or Mitigate the Sources of Condensation

Cooking high moisture foods like rice and broth normally releases a lot of moisture in the air, much of which may end up on walls and windows.

Bathing warm water releases considerable moisture as well. You can install condensation-removing fans or make changes to the way you bathe and cook.

Use The Right Size of Cooling Equipment

Another top causative factor for sweaty walls and windows is cooling equipment running at a higher setting than what your home needs.

Most homeowners tend to think large conditioning equipment means more comfort.

Unfortunately, oversize ACs may create an array of moisture issues that may manifest on walls.

Always adjust your blower to less than 350 ft3/minute to reduce the amount of moisture in the room.

Abandon Your Unvented Heaters

Not only do unvented heaters release pollutants in the air but also moisture.

According to the finds of the HUD, every 1 gal. of kerosene/propane you burn releases a similar amount of vapor into the air which will certainly end up on walls and windows.

By the way, some companies will void the warranty on your home if you install an unvented heater.

Do you live in Florida? Keep the AC thermostat under 75° F

This is not limited to Florida but pretty any other wet hot and humid climate which also includes much of the southwest of the country.

Outdoor dew point tends to be higher in these regions.

If you allow the home to get too cold inside, the vapor in the voids within the wall may condense and create wet spots.

Furthermore, consider consulting your HVAC expert on proper sizing and dehumidification settings.

Identify Symptoms of Moisture Encroachment Early Enough

Sometimes walls end up sweaty because a minor moisture issue was ignored or stayed undiscovered and ended up spreading far and wide.

If you detect a musty smell or discolorations on walls, get to the root of the problem immediately.


To summarize everything, oftentimes, sweaty walls and windows have something to do with moisture seeping into the wrong places.

There are several reasons why water may get in the wrong places.

It can be a result of your day-to-day activities in the home, how your home was set up, or how the home was designed and constructed.