Why Moisture Is Such A Big Problem With Finished Basements

The basement of a house reveals the most about it’s condition. And often times,, it tells a story about the house that has been going on for years.

This is why from an inspection perspective, it is the most interesting place to examine.

But in recent years, more and more homeowners are building finished basements for that extra space and even for an income suite.

While there’s totally nothing wrong with wanting more space for storage at home or collecting a recurring rental income to pay towards the mortgage, most homeowners don’t realize what they are getting themselves into.

They explore fun ideas and conceptualize design concepts to incorporate into the basement and then start renovating DIY style or by hiring a contractor.

Things will look great once works are completed. But a year or 2 later, serious problems that do no go away start rearing it’s ugly head.

The problem, as always is…


Moisture is already the eternal enemy of a house. Even at this moment in time, it is trying it’s luck to force itself through those walls from the exterior of the house.

As you might expect, the basement is understandably at the forefront of this war going on between the good and bad. The basement being the fortress and water being the aggressor.

Some say that the roof is the main shelter against water.

But look at it this way.

The roof and basement will be defending the house against water when it rains. But on dry days, the roof gets somewhat of an off day while the basement can’t relax against the moisture trying to force it’s way through.

Finishing a basement unprofessionally only degrades it’s ability to handle the moisture issue efficiently.

Despite being in the business for years, many contractors still do not know proper way to finish a basement. Either that, or they cannot care any less.

DIY? I urge you not to. There are too many variables you don’t know that you don’t know.

Here’s why.

Water all around

The basement’s primary function is to be a buffer between living area and moisture from the ground. Even though these days households use them for various purposes, it does not detract it from it’s main function.

No matter if it’s made of stone, concrete, or cinder block, water is going to find it’s way through in varying amounts.

This situation is made worse by the constant pressure that the basement has to endure from the soil around it trying to push itself in. This pressure can come from all sides and also from below.

This makes the floor and lower sections of the basement walls maintain a temperature that fluctuates with the temperature of the ground around it.

And because the ceiling and upper sections of the basement wall will maintain a temperature will depend on the weather outside, the contrast in temperature between the top and bottom half of the basement will inevitably lead to condensation as long as there is airflow.

This is a certainty.

On top of that, wood that is a material often used extensively for finishing will absorb moisture from the concrete.

This defeats the any purpose insulation within the walls are supposed to play. Simply because the insulation is guaranteed to get wet. Especially during summer months.

Older houses

Take note that the technology to waterproof basements is still considered a recent breakthrough in real estate years.

This means that most old homes do not have basements that are properly setup to do a good job of keeping water out.

Whether or not they might lead to foundation problems is not discussed here.

Investors and flippers buying them thinking that the basement can be converted into an extra income generating room will be in for a surprise. The money needed to keep the area livable will take away all potential profits and more.

Basements that are not up to task are not limited to older houses.

While newer homes will have to follow building codes in constructing basements, the minimum requirements to meet those building standards is not good enough to guarantee a dry basement.

How to tell if a finished basement is as good as finished?

The very first sign of a problem usually comes from your nose.

It doesn’t take very long for moist areas to give off a funky smell. I personally find this scent as unmistakable. I do run into people who are not able to identify it. Some are not even aware of it.

Another clear sign is when you find mold (mildew) in the basement.

They love to make home in corners, near the floor, and hidden spots under furniture.

Wood that has suffered water damage also loses a huge amount of it’s strength. So if you notice nails popping out of wood fixtures, it is a sign that it might be moisturized. It would be even clearer if these nail are rusty.

One of the best definitive methods of evaluating an area like the basement for moisture is with the use of thermal imaging cameras.

These are handheld devices that uses infrared technology to produce a heat map of the room.

It is an expensive piece of equipment. And the odds of a regular homeowner having one is quite low. But if you have a friend who has one, or a friend who has a friend who has one, try to borrow it. Or better yet, invite him over to conduct a scan.

You would of course, prepare some baked cookies or brownies to reward him for his generous time.

If you are simply too lazy to conduct these checks, ask yourself this simple question. When you walk about in the basement, does the floor feel damp to your feet?

Lastly, if you are a buyer, it is well within your rights to request to take a look at the permits for the work done in the basement.

If the seller is unable to produce any, it is a sign that the construction did not follow building standards for basements.

How to finish a basement properly?

In view of the relentless maintenance costs that you could incur from setting up basement the wrong way, getting it done right the first time can save you a lot of troubles and money in the long run.

But what should you expect a contractor to do to do it correctly?

The gist of everything is that the walls have to be properly insulated and offers a strong layer of protection against moisture from the outside. This means that the focus is on a vapor barrier and thermal break inside the walls.

Without going into the specifics, which you would leave to the contractor anyway, you should expect insulation glued directly to the wall with all gaps securely sealed.

The same goes for the floor. And never go for hardwood flooring.

If doors and windows are to be added into the basement, the plan must not disturb the structural integrity of the house itself.

Door and window trims must be workmanshipped to the max. This is because these are areas that are very vulnerable to water seepage.

Further more, if you are increasing floor space, take note of the capacity of the ventilation system. HVAC systems are usually installed after taking into account the amount of space it needs to work for.

An increase in floor space can be too much for the existing system to operate optimally.

If there are plumbing works in the basement, pay particular attention to the venting around that area. These are without doubt, obvious sources of moisture.

On a final note, it is not impossible to setup a finished basement that has a strong shield against moisture. But the task on hand is often much more complicated than you have imagined.

And often times, you have absolutely no idea what the hell is going on down there. A professional would be a good choice.