Does roofing felt serve an additional function when laid under a
hardwood floor besides being a moisture barrier?
I'm installing 3/4" plank in an upstairs room over a plywood
Do I need felt underneath?
I don't get it. What is with the 'do I need felt' questions this year.
The cost of the felt is such a miniscule amount compared to the other
material why the hell not use it when it is recommended?
I can't speak for the other "'do I need felt' questions this year" but
in my case the cost did not motivate my question.
My question was about the need for a moisture barrier in a situation
where moisture is not an issue.
I asked if roofing felt served an additional function besides that of
a moisture barrier.
I don't get it. What is with the "I don't know the answer but I'll
give the guy a hard time for asking" posts this year.
Thanks a bunch, Harry.
Let me start by saying that I personally use felt on every job. It
takes only a few minutes to put down, costs a few bucks and you have a
nice clean floor to work off of.
When I pull up old strip floors there's always paper between the finish
flooring and the diagonally-sheathed 1xwhatever subfloor. The paper,
any paper, acts as a barrier in such floors. It keeps dust and dirt
from percolating down through the subfloor. Usually the paper I find
is red rosin paper and not building felt. Possibly the use of felt is
just a holdover from the old 1x subfloor days.
I don't think felt's moisture barrier qualities are its main function
in a floor that's over conditioned space. Over a crawl space it's
The subfloor and strip flooring do expand and contract at different
rates, so there is slidng of one on the other. Having paper
facilitates that sliding, but to what degree I can't tell you - never
seen a study on it.
"My question was about the need for a moisture barrier" [underneath
hardwood floor] "in a situation where moisture is not an issue. I
asked if roofing felt served an additional function besides that of a
I have heard that felt between a hardwood floor and the subfloor is
also useful to separate the possibly different directions of expansion
and contraction of the two materials. Less friction between hardwood
and felt than between hardwood and subfloor? I'm not so clear on the
Actually, the felt would tend to hold water against the bottom fo the
strip flooring and keep it wet instead of letting it soak into the
subfloor and escaping that way. Pretty much exactly the opposite of
what you'd want to do.
HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.