I have a sewing room in my finished basement but the basement gets damp and smells of mildew. This could potentially ruin alot of material. The concrete walls are covered with wallboard and painted. The floor is still the bare concrete. There are no apparent leaks in the foundation. It is a walkout basement. It is much better in the winter when the woodstove burns all winter but come warmer weather (SW Michigan) it gets cool, damp and mildewy. There are no windows in this room.
Julie Anne ~ Allegan, Michigan
Hi Julie Anne, What you describe is the classic basement odor, luckily you have a walkout basement which can make it easier to remedy the problem. One of the first things I would try is a dehumidifier, they are usually pretty good at removing moisture and potential mildew problems from a basement during the summer months. Whenever I have a basement that has leaked for some reason I always put a dehumidifier down there for a while to help get rid of the musty smell. Just remember that it has to be emptied on a regular basis. I am not sure where Allegan, Michigan is in regard to Lake Michigan, but I'm sure there is a lot of humidity in that entire area during the summer.
You don't mention if you have air conditioning in your finished basement. If you do, I would keep the basement windows and doors closed on humid days and use the air conditioning. On days when the exterior air feels less humid open up the windows to your basement, hopefully you have screens, and keep the door to your sewing room open, too. If you like to keep your sewing room door closed, it is possible to install a ventilation grate in it to help circulate fresh air. That should help with any dampness you feel.
Lastly, and I have nothing to base this on other than my personal experience, I don't think you will ever completely rid your basement of that musty smell until you install carpet in the basement's finished rooms. Several years ago I was building high end homes with optional finished basements. The basements were walkouts, and the basements that were not finished smelled like basements. The units that had most of the basement finished with sheetrock, insulation, HVAC, and carpet felt and had the odor of the rest of the house, but as soon as you walked through the door into the unfinished mechanical or utility room it smelled like a basement again. The carpet and padding seemed to help contain the odor of moisture which came through the concrete slab even though there was no leak there. You might want to try that if the other suggestions don't work.