Hello everyone,

My question is: Can a cold air return vent help my humidity situation in my basement?

I live in Lower Michigan and have a concrete basement I would like to finish as living space. I have some of it partially finished with drywall, area rugs and some furniture. I have a sump pump to pump the water from the curtain drain under the floor of the basement. The basement is water tight but, is always cool and feels damp. It usually stays 60-62 degrees.
I run a dehumidifier 24/7 but I know that's not enough. I can see, from time to time, the start of mold on some furniture we have down there. Because of this I'm not sure how much to spend in finishing off the basement completely.

There are heat/ air conditioning vents in the basement but, no return vents. I've heard about your central air system helping to take moisture out of your basement.

Can it be as simple as cutting a hole in the duct work and add a vent to the return trunk?
Will this effect how the central air system works as a whole? I don't want to cause problems with the way the system currently works?

Any advise or information will help me decide whether it is smart to spend the money to completely finish off this space or not.

Thank you,
Shaun

Unless the basement was originally designed to be finished I would stick with dehumidifiers. The reason is mold and mildew. I would not take the risk of adding a return to the basement when you suspect you might already have mold present. Why take the chance of circulating the mold spores all throughout your home and that is what will happen if you add a return in the basement.

Make sure your sump has a tight lid to keep standing water contained and try a larger or add a additional dehumidifier to keep the humidity down in the basement area.

What do you mean when you say "originally designed to be finished"? Is there something special that needed to be done when the house was built?

In our area a house get some special attention during the construction phase if the basement is to be finished. Instead of a tar sealed applied to the foundation a special rubber/plastic sealer is used along with a heavy plastic wrap. Naturally the drainage is up sized since after a few years most drain tiles become partially restricted with sand/small gravel/dirt and other items from the down spouts. The interior walls are also covered with a special sealer to help hold down the humidity transfer from the concrete. A vapor barrier is applied and then spacers and foam board is applied behind the finished area.

As you have found out a basement can generate a lot of moisture along with moisture related problems.

Quote) There are heat/ air conditioning vents in the basement but, no return vents. I've heard about your central air system helping to take moisture out of your basement.

Are the a/c vents in the basement open? I would think adding a/c to an already damp basement is adding to your problem.
The 60/62 degrees you say the basement stays, is this with or without a/c going into basement?

I keep the vents closed during the summer months but, do open them during winter to get some heat down there.
The 60-62 degrees is without the a/c. That usually is the temp. year round.
I also want to say that we built the house 10 yrs ago and during some bad weather and/or power outages the basement has had water in it (twice) that had come in through the sump pump crock. The starting of mold, that I had mentioned, was around the times of the basement "floods" or soon thereafter. I say this just to clarify the situation more and to say that I don't have a mold continual problem.
So, I don't think the spreading of mold spores would occur.

When you finish a basement wall like with drywall or other covering you will be leaving a area that cannot be inspected for future mold problems. Mold just loves dark and moist areas to grow.

I am not saying you have or do not have a mold problem but just passing along ideas from items I have seen happen over the years.