Answers to Basement Questions

Our in-house expert answers questions on basement insulation and moisture prevention.

Q. Which basement is better: a poured wall, Styrofoam poured, or block? What is the best way to heat the basement?

A. Poured concrete, insulated concrete forms, and concrete block walls will all perform the same if they are built according to code and engineering standards. So the answer is none is "better" unless you have a specific issue you need to address. Basements are to be insulated and compensated for energy loss depending upon the location, type of basement exposure, local heating requirements calculated by Degree Heating days, and other issues. How one chooses to heat or cool depends upon many factors.

Q. We are finishing our basement and are almost done with the framing of all the interior walls and drywall ceiling. I've talked to the city building department about fire blocking and still am not clear on how this is done. One stud wall is about 4-inches from the cement wall. Do I try to get behind the top plate and nail/screw another piece of wood in there?

Will insulation work, and if so, does it have to be secured somehow? The finished space will be five rooms and cover about 1,000 square feet. I know I'm probably making this more difficult than it has to be, I just can't picture how we're going to get up, in, and back behind there. I hear that the smaller gaps can be filled with "great stuff." Will this "stuff" adhere to both the cement and the lumber?

A. Fire blocking should be installed between the joists and above the top plate of the framed wall in the form of 2x10-inch boards, or whatever of the dimensions of your floor joists are. In other words, you will need to cut individual blocks out of 2x10-inch boards at 14.5-inches long and fasten them between each floor joist over the framed walls.
Where the framed walls run parallel to the floor joists, you can fasten a plate to the top of the framed wall and to the side of the nearest living space joist, so that any fire which erupts behind a framed wall will be contained.

Alternately, you can use fiberglass insulation spray stuffed between floor joists in any location above the framed wall. Some spray foam insulations come in a can. Those manufactured after January 2003 are generally fireproof and will work for smaller areas. Read the fireproofing characteristics on the can before using it.

Q. I'm trying to spruce up my basement a bit. It is unfinished with a cement floor that has lots of cracks in it. Is there a way to make the floor look nicer without actually putting real flooring down?

A. Fill the cracks, etch, clean, and seal them with any number of products available from paint vendors.

Q. My family is finally finishing the unfinished half of our basement for my bedroom. The basement bedroom is directly under the master bedroom. When you are downstairs, you can hear everything that goes on upstairs. What is the best way to soundproof the ceiling so that my wonderful parents won't be woken up when I have friends over and I won't be woken up when they get up at the crack of dawn?

A. The thicker the walls the better. For your ceiling and walls, after you frame them, be sure to apply insulation. Although insulation is not the best sound barrier, be sure to add 2 layers of 5/8-inch drywall. The more rock you have, the better the barrier will be. That is the cheapest way of doing it.

Q. I finished my basement a few years ago. I replaced windows, installed a vapor barrier, seal, and patched walls. I did everything I thought I was supposed to do. We have had a lot of rain lately and noticed a small puddle on the floor by one wall.

I thought that maybe the window was the problem. I pulled off the windowsill and noticed that some plasterboard had black mold. I didn't see water, but I did smell mold. How can I tell if the rest of the plasterboard got wet or has mold? Should I rip the rock down and put up paneling on the exterior walls?

A. It might be best to remove a strip of the drywall about 2-feet above the floor and see what you have. It's best to sample an area to determine to what extent, and how high up, you should replace drywall.