A Beginner’s Guide to Fixing and Preventing Water Intrusion

While serious water intrusion is something we hope you never encounter, it’s likely that, sooner or later, you’ll experience it in some way.

This is especially true if you are a home inspector, contractor, building owner, or even a homeowner.

That’s why this article is going to be your go-to guide for water intrusion. It’ll answer questions like:

Let’s start with the basics.

What is water intrusion?

Put simply, water intrusion—also known as moisture intrusion or water incursion—is when water is someplace that it shouldn’t be. And for our purposes, the context is specific to homes and commercial buildings.

Water intrusion can create both minor and major damage, causing anything from a small, fixable water stain to impacting the structural integrity of a given building.

It can also manifest in many different ways: some obvious and some not so obvious.

For example, you can easily identify water intrusion if you see water pooling on the floor, leaking from a pipe, or dripping from the ceiling.

But water damage can also occur slowly over time, which means it can go unnoticed. This is especially dangerous because by the time the damage is noticeable, it’s a much more difficult problem to fix.

Some common, yet surprising, potential sources—and locations—of water leaks are:

  • Around windows
  • Behind siding
  • Near plumbing (both inside and outside)
  • Around gutters

These sources of water intrusion can produce signs of infiltration that are fairly discrete. So let’s go over some of the signs to help you identify water intrusion:


Discoloration is one of the primary signs of water intrusion problems. And discoloration can manifest in many different ways.

If you notice water spots on your ceiling, then there is likely seepage from the floor above or there is a roof leak. It may also be previous water damage that no longer exists, but in this case, you will want to check for mold growth for your safety or the safety of your client.

Discoloration can also look like staining on the floor or wall. Are your wood floors oddly stained near a major appliance, or do your walls have stains on them? How about your siding?

Discoloration can appear in all these—and more—places, so if you ever notice discoloration, it’s probably time to inspect for potential water encroachment.


Warping, like discoloration, can appear in several places. Moisture is one of the main reasons why you would see warping.

Issues like buckling, crowning, and cupping in your wood floors can all be signs of moisture damage.

Warping can also appear on your walls through bowing.

Mold growthA wood floor with mold growing on it

Mold growth is a dangerous sign of water damage. It can cause not only unsightly stains but also health and allergy issues if left untreated.

This sign is a bit more difficult to pinpoint, so how do you identify mold growth?

Firstly, ask yourself if there is any discoloration. Discoloration, such as black or greenish spots, may be indicative of mold growth.

Another sign of mold growth is a musty odor in a given spot.

Have you ever walked into a damp basement or wet shed and noticed a wet, musty smell? This might be a sign that water is causing mold to grow in an unseen spot.

Deteriorating caulk, sealant, or paint

If you begin to notice that the caulk or sealant around your windows is deteriorating, there may be a leak eating away at them. With windows especially, simple things like condensation can cause caulk to deteriorate over time.

This can also appear on tiled surfaces through deteriorating grout and loose tiles.

Lastly, if the paint on your walls is beginning to bubble or peel, it may be hiding water damage.

Standing water

If you walk around the outside of a building and see standing water, it isn’t a for-sure sign of water damage, but it is a sign that water damage is likely or already present.

Standing water that pools near external walls is often a result of a gutter system that doesn’t direct moisture away from the building. If gutter runoff pools, then that water could eventually damage what is around it. It can cause damage to siding, concrete, walls, etc.

No matter what the sign of water intrusion is, it can be a source of considerable stress. You certainly don’t want to leave these signs unattended. Fixing current damage and preventing future damage (our personal preference) is always the answer.

So let’s learn some ways to fix water damage before discussing some ways to prevent it.

How do I deal with water intrusion?

How difficult water damage is to fix depends on the severity of the damage. If you have major structural damage to a building, then remediation may require demolition and rebuilding. If the floors have been damaged to the point of mold growth or flaking, then the floor will have to be torn up and replaced.

However, water intrusion on a smaller scale can be dealt with fairly easily.

With all of these repairs, it’s important to factor in that you must find the source of the intrusion. If you ignore the source of the problem, any of these fixes will simply manage the intrusion issues instead of solving them.

That being said, here are some examples of what a simple intrusion repair looks like.

Patch the leak

If you have just discovered water intrusion from a plumbing leak, then simply patching the leak will solve the problem, especially if it has not caused considerable damage to the surrounding flooring, walls, etc.

Using an epoxy or fiberglass patch kit, or silicone tape, can be great for fixing minor leaks. If your leak comes from a pipe, you may want to check the way that the couplings fit or if they are cracked.

For non-plumbing leaks, such as a leaky roof, inspecting and repairing the shingles is probably the first line of defense.

Reseal deteriorated caulk or sealants

Windows that need caulking to seal them from moisture intrusionIf the caulk around your windows or the seal strip underneath your door is damaged, a simple way to stop water intrusion is to replace the caulk and seal strip.

Re-caulking the windows will help waterproof the windows, keeping your home safe from both water vapor as well as higher volumes of water from rain.

Replacing the seal strip at the bottom of the door makes the door more watertight and can help keep the building cool in the summer and warm in the winter, which is an added bonus.

Use a moisture vapor barrier

If you determine that the water intrusion is coming from groundwater beneath the building’s foundation, then adding a moisture vapor barrier, like a sheet of plastic, in the crawl space can stop the water vapor from seeping up through the flooring.

After adding the vapor barrier, make sure to use a pinless moisture meter to monitor the moisture content (MC) of your floors to ensure that there isn’t another underlying moisture issue.

While these are some helpful repair tips, the best thing to do is to prevent moisture intrusion in the first place.

Let’s talk about how we can prevent moisture encroachment in the next section.

How to prevent moisture intrusion

Like most things in life, an ounce of prevention is worth a pound of cure. Here are some easy ways to prevent moisture intrusion to save you from future headaches and from spending money on serious repairs.1

Annual inspections

Homeowners, you take your car to the dealer every 5,000 miles or so to get a tune-up right? Why, then, wouldn’t you make sure that your house is in great shape too?

An annual roof inspection—or any other inspection for that matter—can help you catch problems before they become real problems.

Direct runoff away from the building

The building gutters should be arranged and built up in such a way that water always flows away from the building. If not, every time it rains, water will pool and the exterior walls will absorb moisture, contributing to mold growth and the deterioration of the siding.

Even if you live in a place with very little rain, water from outdoor faucets or sprinklers can pool around the building. So make sure the gutters and slopes are working in your favor to avoid water intrusion.

Use a water vapor barrier

We’ve discussed vapor barriers as a repair for a problem, but they can also be used as prevention.

A vapor barrier can be placed in a crawl space. This preventative measure is an easy one, but it can make a world of difference.

Use a moisture meter to check for hidden leaks

While this isn’t the primary use of a wood moisture meter, you can use a moisture meter from Bessemeter to detect hidden leaks.


Simply use the moisture content (MC) measurements from the meter comparatively. Measure the MC of a drier area, and then take an MC measurement around cabinets, appliances, faucets, etc. If the MC around appliances or plumbing is higher compared to other spots, then you may have an undetected moisture issue.

This can help you inspect the problem earlier than you would have and prevent it from getting worse than it needs to be.

Be vigilant!

Nearly all of the above preventative measures require you to keep an eye out for growing problems or potential problems.

If you can simply stay vigilant of areas where moisture intrusion is likely—near plumbing, major appliances, around windows/doors, etc.—then you can catch the problem early or prevent it altogether.

Are you interested in other preventative measures like checking the MC of wood floors before installation (or even before purchase)?

If so, you might consider adding a moisture meter to your toolbox or inspection kit.

A pinless moisture meter from Bessemeter is the way to go if you’re looking for good quality at a great value.