Here's a site to check:

vinyl floor sheeting and OSB board - Flooring Forum - GardenWeb

Maybe you have been here already.

Good luck

Ha, a very pertinent thread as I may be putting some vinyl down shortly.
Previoulsy I've use hardboard which has been fine, and is about the cheapest quickest way to get a nice flat finish.
I don't know if there is anyway to avoid a decent hard underlay over floorboards.
_{(I've got to put some down in the Mother in Law's bathroom...<groan>, but I'd rather have a job to do than sit like a zombie listening to stories I've heard n+1 times before)}
Del

Thank you....I got much more than I bargained for but am very appreciative of you input...the task sounds like I may consider an expert in the field to do it...not sure we can handle all of that...

Thank you again...

missjoan

I am in agreement with timetraveler from my experiences.

I do not regard OSB as a proper underlayment.

Advantac at 3/4 inch is an underlayment, or even 3/4 inch tongue and groove plywood is an underlayment.

I myself in more than ten years of renovations and construction work have not come across 1/4 inch OSB either.

From my experience and reading what timetraveler had to say, I'd say he knows what he is talking about, and recommend you take his suggestions seriously, even over anything I might have to offer.

Advantech is a good flooring. I have not used it but have heard good things.

In the 80s-90s we would lay right over well patched 3/4 tongue and groove interior grade plywood, the chance for plywood seam photographing was an acceptable part of the job, we knew and the customer knew it. At some point in the late 80s the vinyl manufactures started advising an underlayment over the plywood to control this issue.

The first was luann it worked well for a few years until high demand started to bring quality control issues hence the voids I explained above. Then the exterior grade worked fine but as the glues were modified they drew the yellow pigmentation from the moisture repellants into the vinyl if you have seen a yellowing vinyl floor this may be why. If it is on concrete they blamed the yellow glue so the glues started coming in white or an almond color.

There was a time when the install specs would change from week to week with vinyls. one of these was Mannington Gold, this was the first resilient Interflex ( perimeter) vinyl introduced and it was very unstable.Domco, Armstrong and others followed suite with the lessons learned by Mannington, but the product as a whole had many problems and was regulated to the racks at the back on many shops. Some dealers stopped selling them all together.

One week the install spec would say pull your 4" trowel parallel to the wall the next week it would say pull the trowel line toward the vinyl center to allow air to escape while the floor contracted but in the same directions it would say if you could still see trowel marks you had let the glue tack too long, this was an oxymoron, if you had to allow for air to get out it would need to feed between the trowel ridges if you had trowel ridges..... you get the point.

An accepted method for controling bubbles that would form in the interflex styles was apply heat to the bubble then set a block of ice on it.This worked quite well for more than just interflex styles.

I suppose a lot depends on the size of the room.
A small bathroom in the UK is much much smaller than a BIG kitchen in the US,( where you probably need a car to drive from on end to the other)
I've had no problem with hardboard for small areas, and no adhesive/tape etc needed at all when using good quality thick vinyl.
Biggest tip is to get it loose laid and let it settle flat before cutting.(Oh and remove cat from underneath)
Del

Thanks for the tip....and hmmm didn't know we English had a sense of humor...I have always blamed my lack of it on my English heritage......guess I was wrong...

My kitchen is relatively small...10 1/2 by 14 1/2...

And in my case...I'd have to remove the "dog" !

missjoan

For the most part you're supposed to use underlayment grade plywood. No less than 1/4" and no more than 5/8". When you start getting into larger thicknesses, the smoothness of the underlayment starts to become compromised.

My advise, spend the extra few dollars and make sure it's done correctly, especially if you're planning on floating it without an adhesive. The difference between oriented strand board and plywood is fairly minimal.