Replies

1. 
   Amish Electrician | Aug 15, 2010 08:32am | #1

   Putting a wood floor in a basement .... despite at least three FH articles that addressed the topic, the more I think about it, the more I think you'd have more luck getting a Unicorn to wear a hat.

   First of all, it's only fair that I explain that my passion on the topic is the result of a mino flood in a customers' basement last Fall. The completely finished basement had but an inch or so of water in it, yet the cost of repairs was staggering; moreover, it took almos exactly 36 hours for one area the vacuum missed to become fragrant as the mold bloomed. The experience did a lot to challenge my beliefs ... and one of the first casualties was the often-recommended layer of plastic.

   IMO, the first, and biggest, challenge to covering a basement floor is the floor itself. We imagine the floor to be as flat as a foundation slab or driveway, and that is almost never the case. The 1" of water in that flooded basement was nowhere near enough to let it get anywhere near the sump, and various 'ripples' in the concrete made numerous pockets where the water could accumulate. Mind you, this is a floor that looks perfectly flat, and feels smooth even barefoot; yet, put a level on it, and you can see the ripples. Installing the baseboard was a real challenge.

   So, your first step is to get that floor leveled. While you're at it, make sure the entry to the sump is the lowest point. I know nothing of the company you mention, but if they have a product that is intended to be used atop cut-back adhesive, I'd give it a try.

   I say that because dealing with old cut-back adhesive is a real PITA. Indeed, my best approach (so far) has been to paint it with an OIL based paint like Rustoleum, then let it dry. Be advised that it will take at least a week to dry, as the solvents in the paint will be absorbed into the adhesive, and for at least a week the adhesive will become fluid, and 'self level' itself under the paint.

   Even thopugh I've had good results with the paint, the next time I encounter this awful stuff, I plan to try soaking it with one of the citrus strippers, laying a sheet of plastic over it for the night, then see how much can be scraped / mopped up the next day. One reason is that I do have worries about paint solvents possible being ignited by something like the water heater pilot light.

   Now ...  about that plastic sheeting ....

   I have some real problems with the idea. I see it as an attempt to keep moisture out, but an attempt that will fail. At some point there's sure to be some sort of hole in the plastic, so water will get in, but not be able to get out once it's trapped in those little ripples in the floor.

   Concrete is porous, so it is capable of letting minor amounts of moisture drain out. Unfortunately, it will also let ground moisture enter the house.

   Is a vapor barier (like the plastic sheet) the solution? I don't think so. Where does basement moisture come from? Well, I think that the bulk of it comes from the air in the basement, rather than from the ground under it. I believe that the cool earth causes moisture to condense out of the warmer air. There's also the matter of spliis and mop water. A plastic vapor barrier will only trap this moisture against the underside of the wood, leading to problems.

   Instead, I think the solution is to prevent the air from being cooled in the first place. I believe that you can accomplishe this with a layer of foam insulation under the floor (and cover the foam with a layer of paperless drywall). Now instal the flooring.

   Sure, the foam will most certainly act as a vapor barrier; that can't be avoided; we don't want an insulation that will soak up water itself. The difference between the foam and the plastic sheeting is that the 'line' where airborne moisture will want to condense will be somewhere inside the foam, rather than right on the top surface of the film. If the air can't reach that cool layer, it can't be cooled, and thus the moisture won't condense out.

   Why do I want to lay paperless drywall on top of the foam? I say 'paperless' because of mold / termite issues. I do want a layer of drywall, or tile backer board, for fire protection. Especially when laid flat, ALL foams need such a shield.

   This layered approach might not be the only solution. I can also imagine a floor that has an air space under it. With enough airflow under the floorbaords, I believe that the moisture issue would also be solved. As I see it, the trick is making sure there's enough airflow, to all the spaces under the floor.

   Which, IMO, brings us to the REAL issue with basement floors: ventilation. We simply do not pay enough attention to getting fresh air into basements. Think of those fans and windows as 'pumping' moist air out.

1. 
   Lightweight | Aug 15, 2010 05:26pm | #2

   Some new finds and possible solutions.

   I started a reply and lost it so if I am repeating myself I apologize.

   Thank you to Amish Electrician for the great response.

   I am continually amazed at how many different paths there are when one searches for answers, be it online or elsewhere especially when the search criteria are essentially identical.

   But here are some new finds:

   1.) Franmar makes a soybean oil product that seems to do a remarkable job at removing asbestos mastic adhesive - it's called Bean-a-doo Mastic Remover. It appears to be highly effective and safe. They have a video on their website showing its application.

   2.) There is also a subfloor product called Delta-FL which is a roll of hard plastic that has something like soccer cleats molded into it. It is made by Cosella-Dorken (umlaut over the "o" in Dorken)

   I will be ordering the Bean-a-doo tomorrow.

   The foam method that you suggested might still be a warmer and more effective solution. The last point that you made in regard to ventilation I believe ties in with a larger issue I have - and that is with design, both functional and aesthetic.

   It speaks to the question of how homes are used and lived in and how that space makes you feel. A simple point being something like ceiling heights; you could probably compensate the cost for a higher ceiling by decreasing the square footage and still have a space that is more pleasing than a larger square footage space with low ceilings. I read recently in a design book that higher ceilings inspire creativity.

   Many thanks,

   Andreas.