Hardwood Floor Underlayment? Yes or No

NOTE: this is Not a discussion of underlay required for "floating floors" but rather only in reference to installing nail down solid hardwood flooring!

Do I need to put tar paper or wax paper over my subfloor before traditional installation of hardwood flooring? The answer is NO! At least not under normal conditions.

This is probably a question I get asked every week by various home owners that are interesting in installing their own hardwood flooring. Let me suggest first and foremost that felt paper does NOT stop squeaks! It seems to me that this is the most common consumer understanding on why paper is used when installing hardwood flooring, but I'll discuss that a little more, further down the article.

So then the obvious question, considering that we KNOW installers have been using felt paper under hardwood flooring for many years, is why did they do it? Well, I have asked every installer I have come in contact with for the last 20 years and here's their most logical answers...

1. the tar paper prevents moisture migrating from a damp basement up into the underside of hardwood flooring... but how many people have a damp basement today?
   
   In older days, the basement was an infrequently used crawl space with only a earth base, so moisture was an issue... today the basement is usually a fully finished living space with the same environmental conditions as the rest of the house... sooo there is no moisture to keep out of the flooring

If you are installing flooring above a damp crawl space then certainly using tar paper as a moisture barrier is a great idea. But maybe a better idea is to consider other flooring options that are more able to deal with high moisture conditions.


2. In the old days subfloors were traditionally made of rough lumber. Installation of hardwood flooring using wax paper was common, to prevent the slivers from the rough lumber getting caught between the tongue and groove connection of the neighbourhood boards of hardwood flooring. If a sliver of wood got caught between the boards then it would leave cracks and make wood floor installation more difficult.
   
   Today we always use oriented strand board (OSB) or plywood as the subfloor so dealing with the fibers of rough lumber is rarely an issue... and NOT a reason to use a hardwood floor underlayment or wax paper.

As pointed out earlier, many suggest that we should install felt paper to stop squeaks--- Felt Paper does not stop squeaks--- usually squeaks are caused by

1. subfloor (plywood) movement against floor joists (especially in cases where bracing has been removed to install air ducting)

2. strips of hardwood flooring moving against each other, particularly when nails have been spaced too far apart or tongues broken during installation.

Felt paper will NOT help either of these conditions.

Thus make a decision that makes sense given your particular job site issues and don't work under the illusion that underlay paper is an easy solution to moisture migration or squeaking in hardwood flooring installation. If you want to use it, go for it. Its not expensive. But deal with squeaking and moisture as separate issues.

As a last point, I really don't like using tar paper as a hardwood floor underlayment under any conditions as my personal hangup is that it adds toxins to the home environment that I don't want to breath. If its not necessary then why expose your body to this element!

Further Information:
Hardwood Floor Installation