On Oct 15, 10:49*am, Joe wrote:
On Oct 15, 5:52*am, Jim Elbrecht wrote:
"Colbyt" wrote:

First of all I don't consider 5/8" over 1/2" to be under-layment at all.
That is called a floor. *Half inch is nothing.

Under-layment is something you put down to provide a smooth clean surface
for tile or vinyl and can be run either way. Usually it 1/4" and added to at
least a 3/4" sub-floor.

I would install it *with the 8' running across *the joist and try my darnest
to hit the joists. *I would stagger the seams so that the new does not line
up with the old on either direction. I would use a minimum of 8D sinkers to
secure it. Now you have a floor.

To minimize potential squeaks I would use a single layer of 30# *felt or a
double layer of 15# felt. Alternately you can use liquid nails or the like
in lieu of the felt.

Squeaks come from the wood sliding against the nails, not from the
underlayment sliding against the subfloor.

What he said. * * Though he didn't make clear that all those 8D nails
go into joists.

*THEN* you put your 1/4 subfloor in if you need it and use the short
ring nails.

Jim

I already have a subfloor. The subfloor goes on the joists.
Underlayment goes on top of the subfloor.

Thanks for the definitions. He used the wrong word, so stop being a
smartass and learn something.

"Screws are just plain out of the question"...? Why? It's a superior
installation, doesn't cost a hell of a lot more, and unless you're
doing an entire house won't take all that much more time. Even if you
are doing a whole house, the superior installation is worth the time
and money. Rent an autofeed screwgun if you're worried about the
time.

If you are going to use nails, you should know what nails do, and how
they are supposed to work. Underlayment nails, and roofing nails, are
designed to penetrate completely through the wood sheathing. They
hold much better that way and are far less likely to back out over
time. If you are concerned about the appearance from below (you like
the look of exposed 1/2" CDX???), then you should look into nailing
just at the joists, glue the underlayment down and weight it so there
are no gaps between the two layers.

R