Homasote for concrete floors under carpeting?

[sleepy hollow]

I saw this product briefly on an episode of Ask TOH. I am finishing my basement and wondering how to "soften" the concrete slab. Supposedly Homasote is something that can be put down directly on top of the concrete, and under the carpet and padding. I believe it is 1/2" thick so there would be minimal loss of height.

I wondered if anyone has any experience with this product or whether there are any suggested ways to address a slab floor to try to mimic a wood floor?

Here is the web site I found:

http://www.homasote.com/comfort.html

Thanks.

[Cole]

I have never used it but it looks pretty good.

The real big question.

How much is it?

[Tom R]

The Homasote plant is not too far from my house, - - it's pretty good stuff for certain applications, - - the thing I used to use it for the most is floor protection during construction, - - yeah, it comes in 4 X 8 sheets, 1/2" thick, - - it's fairly rigid, - - usually gray-colored sheets, - - best I can explain it is it's kind of like half way between a mixture of cardboard and felt, recycled together, - - it is popular for underlay of carpets, - - makes for very comfortable walking, - - one thing is, - - it is somewhat absorbent, - - if you have pets, - - or if it's in a 'spill' area, - - lay plastic in between.

[Cole]

How much is it, Tom?

[Tom R]

Been years since I bought it, - - but I'll take a guess and say around $15 -$20 a sheet.

[sleepy hollow]

I found a price discussion on the web site that indicates it is $15-25 per sheet depending on shipping costs. Reasonable considering the cost of 3/4" TIG plywood is creeping up above $30 per sheet.

I think I saw that the plant is in NJ, yes TomR? I live in VA outside DC, so I am hopeful I can find it somewhere here for a reasonable cost.

Looks like they also recommend using roofing felt under the Homasote on top of the slab.

Not sure whether putting a vapor barrier on top of the suff would be good or bad. But it certainly looks like it is absorbent.

[Sweep]

I have used this stuff for 40 years. On a wall it is the best pin-up surface ever made. Drafting room walls are covered with it. It can even look good when painted or wrapped with fabric if the edges are trimmed well.

But on a basement floor I would be concerned with moisture from the slab. It has always been my understanding that homasote was for above grade installations. I doubt that adding grooves in the bottom serves much purpose other than to reduce warping.

Before using homasote, put down a sheet of polyethylene and tape the perimeter continuously to the slab. See if the slab is damp after a week or even a day. Everything depends on your ground water and soil conditions and if your slab had a moisture barrier placed below it when it was built. Perhaps placing a sheet of 6 mil polyethylene under the homasote would be sufficient to keep it dry but I would not put much trust in building paper.

Another method is DELTA-FL which only adds another half inch or less in height.
http://www.cosella-doerken.com/deltafl/index.html
It is a 1/2" thick waffled plastic underlayment that is advertised for use under plywood or OSB for a finish floor of carpet or wood or directly under a thin T&G laminate floor system on a foam sheet. If you place the wall furring/studs over the DELTA-FL, moisture vapor might actually travel to the walls where it presumably would dissipate without causing trouble (especially if there is no wall vapor barrier.) I would expect it to provide a very comfortable floor.

I have never seen it installed but you would be a great test case.

This would be a good time to test for radon gas under your slab.

[sleepy hollow]

Thanks for the suggestion. I'll definitely investigate the link/product you provided. The Homasote moisture issue is certainly one I do not wish to explore. Living in Virginia means dealing with very high humidity throughout the warmer months of the year.

By the way, there is a plastic vapor barrier beneath my slab. I know this because I have had to break through the slab to install a sewage ejector pump/basin for the full bathroom I am installing. It is dry as a bone down there, with plenty of gravel covered by plastic sheeting. Looks very well done.

I also have a Radon mitigation system installed in the basement with a 6" PVC pipe through the slab venting through the roof. I personally do not subscribe to the faddish concerns about radon. I do not know anyone who has become ill due to radon, and I don't know anyone who knows anyone who has been affected by radon. Mostly radon poisoning is a statistician's hypothesis. But that is just my peculiar opinion.

I do know companies who have made money selling radon testing and mitigation systems however.

Thanks again for the suggestion.

[Sweep]

Although this is a subject far off topic, I think something has to be said in response to such strong cynical remarks about radon "poisoning".

There can be no controversy regarding the existence of radon or that it is known to cause bronchogenic lung cancers and other respiratory problems such as emphysema, pulmonary fibrosis, chronic interstitial pneumonia, silicosis, and respiratory lesions.

The radon controversy is regarding the amount of radiation exposure that is acceptable for children and others who might spend a lot of time at home especially in poorly ventilated remodeled basements. The controversy is complicated by a large variation in the amount of radon found in different parts of the US and the fact that the exposure time required for health symptoms to appear is so much greater than the average cycle of homeownership and the lack of direct proof of which environmental condition caused a particular lung cancer or emphysema.

You will probably never know of someone to die of lung cancer or emphysema attributable to radon but if you live long enough you will probably know of people to die from lung cancer that cannot be attributed to smoking or anything else in particular. Right now all that science can tell us is that, statistically speaking, one out of four of those cancers was probably caused by radon.

Radon may not be considered a serious health problem nationally, but it is a health problem to be taken seriously by individual homeowners because many basement dwellers are our children.