Redoing basement bathroom - need advice

11 years ago

I'm redoing a basement bathroom, and I had some thoughts and need some advice. First let me tell you about the bathroom. It has manufactured wood flooring, which is deteriorating in the bathroom from water exposure. I want to tile instead of wood, and since it is concrete under the wood flooring, should be minimal problems. However, on the walls the bath has some of that old, nasty, coated particle board that used to be common enough. But now looks ugly ugly ugly. My wife wants to redo more than just the floor while we are at it, and I agree, but I have to make some decisions. I also don't want to make my life complicated, as I am doing all the work myself.

Now you need some detail. I bought the house a few years ago. It was built in the early 70's, wood frame. The house is on a slope, and the basement is about half below grade. Poured concrete foundation. So on the back wall, where the bath is, the soil ends about 4-5 feet above floor level. The bath has a typical cellar window, about 14x28 or 30, something like that. Pretty standard - I replaced a couple of the 1974 originals when the glass broke, and it was a HD standard offering size. The basement was "finished", about 80%, probably about the same time the house was built. By finished, I mean it has wood framing against the concrete foundation inside, finished with sheetrock. There are two functional rooms and a "cellar" area where the furnace is.

I am in the northeast, so freezing winters are normal. When I bought the house, I thought the finished basement was great - and there are no known water problems. However, I have since learned that covering up a concrete foundation like this can lead to moisture buildup BEHIND the sheetrock - and mold. I've seen slight evidence of mold in the cellar area, but I keep a dehumidifier down there, and there are some holes punched in the sheetrock, high and low, which may have been done intentionally to increase the air circulation behind the sheetrock. So we haven't seen anything develop since we have been here.

I planned to tile around the tub area, which is next to the outside wall (and foundation), and under the window. I was thinking of using a concrete board to provide a good foundation for the tile - and I had an idea. What if I just knocked out the wall next to the foundation, and tiled directly on the foundation? It is concrete, after all. I realize it would be a little colder in the winter, but we aren't talking a very big area - the bathroom is exactly as wide as the tub.

Am I thinking I'm simplifying when I am actually making things more complicated? Will there be some drastic consequence I have not thought of? Is there something I should consider before I do this?

Comments (3)

fnmroberts
11 years ago
Floor tile is a great idea. Wood on a basement floor, and especially in the bathroom, is a recipe for problems.

I wouldn't tile directly against the foundation wall. Since you are in a climate with freezing winters, I really believe your concrete should be insulated plus a vapor barrier behind concrete board/tile. My intuition suggests that moisture from the bathroom would be a significant cause of any existing mold brought on by condensation. If you remove the existing drywall, it might be better to have foam insulation pumped between the existing studs. I know you want to DIY but some things are too specialized.

An exhaust fan needs to be present and used too.

Any existing mold MUST be dealt with or it will return.

Make certain the soil is graded away from your foundation.

Don't want to be discouraging but preparation for any project is always where the work is. The reward is knowing it is done correctly. Good luck.
hiero
Original Author
11 years ago
Ok, then! I won't remove the framing when I get in to it. I have not the faintest idea if they installed a vapor barrier when they originally installed all this stuff - but, since the mold/mildew I saw was in a fairly small area, I think they may have, and whatever moisture problem I had in that area is from a different cause.

I found an excellent article about mold and mildew problems, but I neglected to save the link. It taught me a lot tho. I am aware that whatever it was will never truly go away, but I don't think it is currently active. I also don't think it was from the bathroom moisture, because it is about 6-10 feet farther down the wall, in the "cellar" section - separated by a stud wall and all that distance. Of course, it COULD be, no doubt, but I also believe in KISS, and that would tell me that a different problem was the cause - like perhaps the washer exhaust repeatedly backing up into the cellar area.

We have an existing exhaust fan - but I've realized, reading here, that we should be more rigorous about using it.

So I'm back to the original concept - 1/2" concrete board for the wall tiling! I will guess the current insulation behind whatever is there now is fiberglass - most of the house insulation is, and I know other areas of the wall inside the foundation are fiberglass. Foam could be arranged, I suppose. You are thinking of urethane foam?

Thanks!
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fnmroberts
11 years ago
Unfortunately you won't know what is there until de-construction begins. I'm not a fan of fibreglass insulation for basements becasue in the event of water (or condensation) the insulation remains damp behind the wall. Yes, urethane foam would be the best security going forward as it is non-absorbant and fills voids.

Humidity, be it from the bathroom, laundry or nature, will condense on the coolest location. Distance from the bathroom is not a factor. Year around use of a dehumidifier in a basement is a good idea becasue humidity from throughout the house will always appear in a cool basement.

When you see the existing framing you'll know if it is moldy. These walls are not structural so you can remove and replace if necessary. Dependant on the on-center of your studs, 3/8" concrete board (Hardiboard) should be fine for walls.