I I shouldn’t have to ask but HD was no help

I’m putting 1/4” underpayment over 3/4” plywood. What fasteners? 7/8” narrow crown staples were used in the old underpayment for the most part but some ring shank nails were used around the seams. HD was of no help

Glue it and screw it.

That's what she said!

Is that how that works? I'm not good at this game. I'm also no use at answering the real question. carry on.

Uh, that sounds like the makings of the all time most embarassing 911 call 

Edit: I shouldn’t post when I’m waiting on a pizza..

what I was questioning is whether I can use the Staples alone.. The old flooring had a layer of vinyl flooring in between the underpayment and plywood which has been removed and there wasn’t any issues with the old flooring. The nails were used near a few seems but not all for some reason.

2nd for glue and screw.

Find all of your squeaks first, screw them down tight then glue and screw the underlayment down.

I'd use a maximum spacing of 12" in every direction. 8" would be better.

I've done this a few times.

+100 for screws and glue, my floors squeak all over the place,  when it is time to replace the carpets the floors are getting screwed. 

In reply to Woody :

(to be read with a Canadian accent so you know what it's aboot)

The entrepreneurial prostitute

Put glue where clients put their hoot

She said with a grin

They'll pay to get in

And then they'll pay double to get oot!

Ok. But how long should screws be to secure 1/4” to plywood below. The 3/4” plywood is already secured from previous work. 

Before deck or construction screws were a common thing, I put down a layer of 7/16 plywood to bring my living room floor up to the level of the rest of the house.  1 1/2" ring shank nails are still doing the job quite nicely, 30 + years later.

when I pulled up the 1/4" underlayment to lay down bamboo flooring, it was held down by ring shank nails every six inches.  I had to cut the underlayment into 1 foot squares and drive a wedge under each square to get them up.

In reply to rustybugkiller :

1" screws would be sufficient. Shorter, like 3/4" are harder to hold and get started with my old, fat fingers.

I used to use ring shank nails, as others have mentioned, They used to be the standard before screw guns became so prevalent. I prefer screws, they aren't going to back out and I'm a lot older now, they're easier to drive than nails for me.

Staples or screws are your choice.  Don’t worry about the next guy removing it, it’s not your job to make it easier for future removal unless you anticipate that being you.  I blew the trigger seal out on my narrow crown stapler at the beginning of the last floor underlayment install but we had a 25 pound bucket of drywall screws.  Then all the heads got filled with skimming mortar.  Next guy is going to curse me.  

If you have access to a roofing nailer you could do ring shank roofing nails. It would go really fast.

I removed a 1/4" underlayment that had been secured with staples. That stapler must have been the installers fancy new toy because he used hundreds of them. I was yanking staples with channel locks for weeks as the underlayment would splinter to pieces as I pulled it up leaving about half the staples in the sub floor.  After thinking I'd pulled up all of them, I'd inevitably kneel onto the floor working on something and "find" one I'd missed.  

Berk you, Patrick. Berk you. 

Your best bet is to read what the manufacturer recommends. For example (if you're buying patriot timber underlayment):

http://www.patriottimber.com/sureply-installation-guide/

They say:

No glue

Use a narrow-crown chisel-tipped galvanized staple driven by a pneumatic gun (or screws, but screws will be a PAIN).

Use LOTS of fasteners. Every 2" around the perimeter and every 4" in the field.

They built the wood, they know how to put it down so that you'll never call them up to complain.

Ian F said:

I removed a 1/4" underlayment that had been secured with staples. That stapler must have been the installers fancy new toy because he used hundreds of them. I was yanking staples with channel locks for weeks as the underlayment would splinter to pieces as I pulled it up leaving about half the staples in the sub floor.  After thinking I'd pulled up all of them, I'd inevitably kneel onto the floor working on something and "find" one I'd missed.  

Berk you, Patrick. Berk you. 

Next time you have to do this, use a floor scraper. Should shear the staples off level with the subfloor, or pull them right out. WAY easier than using channel locks or vice grips to pull each one on your knees. After you get the bulk of them out/off, the stubs can be pounded down under the top using a hammer and move on with life. Glue will make all of this impossible.

Why are you looking for fasteners at Harley Davidson? Is it because they naturally shake off parts?

I used this to pull the staples out. Still have to get on your knees but faster than vice grips. 

In reply to the_machina :

We did use a scraper.  Or tried to.  The flooring and staples laughed at it.

You assume the subfloor is a smooth surface to scrap against.  In a 120 year old house that has already been remodeled who knows how many times, nothing is flat, smooth or square.

In reply to rustybugkiller :

I have one of those.  Actually found channel locks to work better.  The usually longer handles give better leverage and less effort.  Grab the staple with the jaws and then roll it out of the floor.