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Why Does My House Have Wet Walls?

Published on Tuesday January 17, 2017

FACT: Your house shouldn’t have wet walls. Sure, we’ve all seen condensation in our bathroom after a long, hot bath or shower — but those droplets should dry by the time you’re done using the hair dryer. There shouldn’t be any marks or mold left behind. And there certainly shouldn’t be any damp patches on walls after heavy rains.


If the walls of your home are consistently wet, sweating, damp or slick, you may have a moisture problem. Here are a few common signs that you have too much moisture in your home:

  • Peeling paint or wallpaper
  • Water marks or staining
  • Wet spots on the wall or ceiling after rain
  • Water running down inside walls
  • Walls that feel damp to the touch
  • Visible mold
  • A musty, stale odor

What causes wet walls?

The science of your walls sweating is simple. Either moisture can’t get out of your home, or there’s moisture is coming in. Condensation, leaks and inadequate drainage are the most common causes of moisture problems in homes.


What causes condensation?

Condensation occurs when hot, moist air hits cold, dry air. This meeting causes water droplets to form on the cold surfaces (like your walls). This kind of moisture is what you’ll find on the bathroom walls after a super-hot shower.

Condensation on internal walls is more common in bathrooms and kitchens, where steam is produced by bathing or cooking, but it can be found in any room, including your bedroom or living room.

Homes are prone to problems with condensation during the colder months of winter.

A large temperature difference between the air outside and the air inside your home encourages condensation on surfaces like walls and windows on the inside of your house.

This can encourage mold growth and drywall stains. The good news?

There are relatively easy solutions to condensation issues and interior walls sweating, such as exhaust systems, dehumidifiers, and ventilation improvements.

  • Exhaust systems. An excellent option for high-moisture areas like kitchens and baths.
  • Dehumidifiers. A DIY solution to wet walls. A dehumidifier collects excess moisture in rooms that don’t have exhaust systems.
  • Ventilation improvements. Adequate roof ventilation controls moisture levels in your home, saving you from a premature roof replacement.


The most obvious cause of leaks are plumbing problems.

Almost every homeowner’s dealt with a leaky bathtub or sink. Also common are issues with water-wielding appliances — washing machines and dishwashers are often the culprit.

What else lets water inside your walls?

Water can sneak through roof penetrations like skylights, vents and chimneys, causing wet walls. Cracked masonry and failing flashing around windows and doors are other potential problem areas.

If you ever find damp patches or spots on walls or see wet spots on your ceilings after rain storms, leaks are likely the culprit. It’s important to act fast when you see a damp wall after heavy rain because they can cause both short- and long-term damage to your home.

Ice dams can be especially troublesome.

Heavy snowfalls, combined with inadequate roof gutters, insulation or ventilation, creates a perfect recipe for ice damming.

What are ice dams? 

Imagine a snowstorm. You get some snow buildup on your roof. Your attic, unfortunately, is not properly insulated or ventilated, so the snow starts to melt. Hey, that’s a good thing, right?

Wrong! It’s still really cold outside. Once that meltwater gets in your gutters, it starts to freeze. Pretty soon, ice is blocking the gutter — hence the term “ice dam” — and that melting snow still needs to go somewhere.

But where? Maybe it spills towards the ground, freezing and dragging your gutters away from your home. That’ll cost some money to fix. Maybe the water will flow back onto your roof, looking for any tiny crack or crevice to sneak through. Now you have wet walls and, potentially, a seriously damaged roof.

Last winter, Allstate reported ice damming in Delaware, Washington, D.C., Maryland, Virginia and West Virginia after severe weather hit the region. The insurance giant warned homeowners of the potential for water from ice dams to leak into homes.

So what can you do if you suspect you have a leak that’s damaging your interior walls?

  • Identify the source of the leak. Don’t mess around — call in a home inspector to help you identify the water source if you can’t find it yourself, especially if you find damp patches on your walls after heavy rain.
  • Repair the problem area. Fixing a leak can be difficult. Damaged pipes, flashing or gutters often require the skills of a plumber or a professional roofer.

Inadequate draining and “damp”

Damp can cause wet walls in a home

Wet walls can also be caused from rising penetration and “damp.”

What is rising damp? 

Rising damp occurs when moisture is pulled upward through porous materials by  capillary action. Set the edge of a paper towel in liquid — the liquid sort of “crawls” up the towel.

Building materials like plaster and drywall can act like that paper towel, bringing moisture into your walls from the ground. Over time, rising damp often leaves mineral deposits and “tide marks” at the base of your walls.

What is penetrating damp?

Penetrating damp is similar to rising damp, except that it doesn’t necessarily rise up a wall — it just comes right in from the source. Leaks can cause penetrating damp in some situations. Porous block and block wall seams of basements are two common areas where you’ll see penetrating damp in homes of the mid-Atlantic region of the United States.

Areas like Virginia, where soil may expand, are more susceptible to bad drainage. Shifting soils create a lot of pressure on basement walls, causing them to bow, buckle or crack. These cracks, combined with wet soil around the foundation, are the perfect entry point for moisture and can easily create damp walls after heavy rain storms.

Look out, Mid-Atlantic: The basement specialists at ValueDry Waterproofing point out that “the vast majority of homes in Maryland, Delaware, Washington, D.C. and Virginia are prone to basement waterproofing issues.”

The most common cause of both rising and penetrating damp is inadequate ground and surface drainage. Excess water from downspouts, runoff or saturated ground can easily penetrate even the tiniest cracks in your foundation, or wick through porous walls.

This moisture can make your walls feel wet as it is prone to causing damp patches on walls after heavy rain. You may even see water flowing onto the floor from the edge of the wall.

Eventually, this moisture can seriously damage your walls or foundation. Mold may even begin to grow, causing a musty smell or — worse — health problems.

The best ways to fix moisture from rising and penetrating damp is through improving surface water drainage, repairing damages, and ventilating the space.

  • Improve surface water drainage. This is the most effective solution for most cases of rising and penetrating dampness. Redirecting water keeps it from coming into contact with the surface in the first place. You may need to do things like redirect downspouts, regrade your property, or install French drains to redirect surface water problems.
  • Repair damages. Once water drainage issues are solved, repair the damaged structures to eliminate mold and prevent further damage.
  • Ventilate the space. Make sure your home has adequate airflow. This allows surfaces to thoroughly dry, preventing future moisture problems.

Is your roof the source of wet walls in your home?

Rain can cause wet walls in the home.

Since missing and damaged shingles can lead to serious issues down the road, it’s best to tackle roof damage at the first sign of trouble. If your home has wet spots on ceilings or walls after rain or damp walls after heavy rain storms, it may be time to replace your roof. Rely on the experts at Long Roofing — we build trust and peace of mind into every LONG roof.

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