So here’s the story…
I recently built a home theater and wet bar in our basement. I started with a completely unfinished basement; nothing but concrete walls and concrete floor.
Even though I was planning on hiring a contractor to do most of the work involved with installing the walls and flooring, I wanted to make sure everything was “done right.” I first bought a book called Complete Basements by Stanley. I did not like the approach used in the book, so I did my own research - mainly on the Internet - and came up with an approach I believed was much better. I provided this information to my contractor, and made myself responsible for acquiring all the materials. He did all the construction type work (framing, drywall, flooring, etc.) while I did everything else (electric, plumbing, HVAC, insulation, ceiling, etc.). It worked out well.
Below is the approach I used for installing walls and flooring in our basement. The approach I used was not to try and stop water vapor from entering the basement; trying to stop water vapor from entering your basement (using coatings and thin vapor barriers) is basically a losing proposition, and can actually do more harm than good in the long run. The approach described below allows water vapor coming up through the concrete floor to be routed to the edges of the room, wherein it finds its way out and gets sucked up by the dehumidifier. I also chose materials that were minimally affected by moisture and did not promote mold growth.
These are just recommendations, and your mileage may vary depending on your circumstances. I also don’t have a stake in any of the products I used, so feel free to check out substitute materials. We live in Ohio, BTW:
1. If there are any water problems in your basement, fix those before installing walls and floors. This is very important. Do not cover up the problem or use “quick fix” techniques to try and fix it. We were fortunate in that there were no water problems in our basement.
2. Do not apply any kind of coating to the concrete walls or concrete floor. At best, a coating will do no good, and simply waste your money. At worst, a coating can create enough hydraulic pressure to crack the concrete. If a coating is already on the walls, don’t worry about it; just leave it there.
3. Vacuum the walls and floor. Apply caulk to cracks and crevices.
4. Install the subfloor first. The subfloor should go right up to the concrete walls, but you should leave a 1/8" gap between the flooring and concrete walls. Lay down the following, in order: a) Good quality landscaping material. b) DELTA®-FL plastic subfloor. c) ¾" AdvanTech® sheathing. d) Final floor material. Tape the seams in the DELTA®-FL using a tape approved by Cosella-Dörken. The “sandwich” created by the landscaping material, DELTA®-FL, and AdvanTech® should be secured to the concrete floor using flathead 1/4" X 2-1/4" Tapcon screws. Use approximately fifteen screws per 4’ X 8’ sheet of AdvanTech. You need to pre-drill the holes for each Tapcon using the correct masonry bit and a good hammer drill. (Have five or six masonry bits on hand, as they dull quickly.) At first I was using a cheap B&D hammer drill, and it was very difficult to drill the holes through the concrete. My contractor gave me a DeWalt to use, and it was a breeze. For best results, dip the threads of each Tapcon screw in caulk before driving it in.
5. For the walls, glue T&G sheets of extruded polystyrene insulation (a.k.a. “XPS” and DOW “Blue Board”) directly to the concrete walls. I would recommend using a thickness between 1 and 2 inches. Thicker insulation is better, obviously, but it also decreases your living space. We have a small basement, so I just went with 1-inch extruded polystyrene insulation. Make sure you use adhesive that is designed for polystyrene. And then you frame the walls with 2X4s. The 2X4s should go right up against the insulation. Install electric, plumbing, and 3.5" unfaced (i.e. no vapor barrier) insulation between the 2X4s. And then screw ½" DensArmor gypsum boards to the 2X4s. I went the extra step of screwing and gluing the DensArmor to the 2X4s. And then mud, primer and paint the walls. I used Sherwin-Williams products exclusively.
6. Install the final flooring material after the walls are completely finished. You can put down just about anything you want (carpet, tile, engineered hardwood, melamine laminate, etc.). In a basement, the only thing you should not put down is solid wood, e.g. ¾" oak. I put down an engineered hardwood floor. Each plank was 9/16" X 5". It looks great. This type of flooring is constructed with multiple plies of wood, with a top layer made of solid hardwood. The top layer is called the “wear layer.” If you go with this option, the most important variable is the thickness of the wear layer; the thicker the better, obviously. Most engineered hardwood floors have a 1 mm (or less) wear layer. I installed flooring that had a 4 mm wear layer. I found it on the Internet, and it was actually cheaper than flooring sold by Lowe’s w/ a 1 mm wear layer. If you install an engineered hardwood floor, make SURE you use the correct staples and staple gun. (Most staple guns are too big for engineered hardwood floors, and they end up splitting the wood. My contractor did not have the correct staple gun, so I ended up buying a staple gun from the online flooring retailer from whom I purchased the engineered hardwood floor.)
As mentioned, I hired out some of the work that I felt I was not capable of doing. I did the electric, plumbing, and HVAC, while I had a contractor do the floors and walls. He was a good guy, but like most contractors was “old school.” I did the research, and told him the way I wanted it done.