After doing a bit of exploring last night to answer some questions in another thread of mine, I poked a bit at the laminate flooring on my second floor to confirm if I was correct about there being 1950-1960's laminate on top of original 1930's Hardwood.
The easiest place to access the answers was the metal bracket that covers the corner of the top stair tread. I removed the 4 screws (standard head, aka flat head screws) and the bracket was off.

Here is what I found;



There is original hardwood (not visable in the photos) the stair tread (huge 1 3/4" thick), 1/2" plywood subfloor, then laminate. The laminate is glued to the subfloor, but I cannot figure out how the subfloor is attached to the hardwood (glue or nails). I can confirm the laminate flooring is from the late 50's or early 60's as it is the exact same flooring and pattern my grandparents had in their home which was built (flooring installed) in 1959 or 1960.

So my questions are;
What would be the easiest way to figure out how this was attached? I can't pick at it where I looked as it's a very high traffic area (top of the stairs).
What are the odds it's glued instead of nailed?
If it's glued, suggestions on how to remove the subfloor with minimal damage to the hardwood under it?

Any thoughts or suggestions?

This is not a rush project, but I would be looking to complete within the next 3yrs (alone with a few other projects).

I'll be removing the carpet and restoring the stairs as well. Hate the carpet and the stairs look amazing already, recoving the wood treads would bring them up that much more. That will be another thread.

 

I'm afraid you won't be able to find out until you actually start pulling the plywood up.

 

I don't know of an easy way to tell other than to start tearing it up and see what you've got. I'm thinking there must have been a problem with the original floor for them to put down 1/2" plywood before the sheet vinyl. If the wood underneath where good I assume they would have just put the vinyl down on the hardwood.

 

If I had to guess, I would say it was to reduce bounce in the floor, and subsiquently the noise of the floor. The main floor is the exact same floor (sub and hardwood) with the same 24" OC and you can hear the floor creak as you walk on it. Reminds you it's over 75yrs old.
Again, this is just a guess.
I think I'll have to make sure I have a backup plan if I start pulling this up and find something I didn't expect.

In the end, I'm hoping the flooring was done for the same reason people put shag rug on nice hardwood floor.

 

I can certainly see the logic in your hypothesis, 24" OC structure is not going to make for a solid feeling floor. As said, I think you have to decide whether you're in for this and, if so, just start tearing up the plywood and then planning your attack from there.

 

That is pretty much the plan. Will make sure to budget for a subfloor and tile replacement should there be something totally out there wrong with the hardwood.

If the subfloor is glued down, and suggestions for removal besides pry and lift?
Would there be any sort of light solvant I could use to help release the glue (guess that would mean knowing what type of glue would have been used and from what decade)?

 

I don't know of any solvent that you could use to get the plywood up. It will be almost impossible to physically get the solvent to the glue until the plywood is up. I would not even use solvent to remove any residue. Instead I'd go for really coarse sanding like 20 grit. Hopefully though you will find that it was just nailed down. Hopefully they did not use tar (I've seen that once).

 

It's really hard to say if they nailed or glued it. I would assume nails given the age, but the flooring was glued down to the subfloor, so who knows.
I'll try to find a corner where I can explore without working in a high traffic area.