"....it's only 16 years old". Hmmmm. Is this sheet vinyl, vinyl tiles or first generation vinyl planks?

At 16 years old, I would say your floor has hit the end of the road. Certain situations in the home environment will reduce the longevity of a floor. Some of it has to do with environmental controls. Some of it has to do with the material chosen. Some of it has to do with the type of install (full spread glue down vs. perimeter glue down). And some of it has to do with the subfloor....other issues might have to do with maintenance (cleaning schedule and materials used).

If you add up all the "little" things that reduce the life of a floor, you can achieve a floor that has "died" 10 years before it "should". Many floors have a 20 - 25 year life span. Some vinyls used to have a 15 - 20 year life span. It all depends on what you started out with.

I would say it is time to have it all dealt with...right now. If you want to keep the bathroom and the cupboards to save yourself $200 - $500, then feel free to keep 16 year old vinyl that will fail in the next 5-10 years.

As for floor heights regarding the carpet, only you can decide what you want to do. It sounds like the vinyl was raised so that it sat at the same height as the carpet. This is common - carpet is often 1/2" or higher where as lino and vinyl are 3mm (1/8") at best.

I would say it is time to look at dealing with everything. The product is most likely beyond repair. Even if you repaired it, you would pay several hundreds of dollars just to get another 3-5 years out of it. Those hundreds of dollars would go a LONG way in purchasing and installing new flooring.

Post photos if you can.

Yeah, good idea, here are a couple of photos and I could post more photos if necessary. I don't know what kind of vinyl flooring the previous owner installed, but it looks like sheet vinyl to me, see first photo below. Is there a way I can see whether it is full spread glue down or perimeter glue down? The crack you see is on a plywood subfloor, but part of the vinyl flooring is on boards that are made of wood chips (don't know what the name of that material is) at least that is how the subfloor looks like from the basement (the house has an addition to the back, hence the different subfloor materials) My wife cleans daily, mops weekly with normal household cleaners like diluted Lysol, don't know about the previous owner, but probably not much different.

One of my first thoughts about a new floor was a laminate with a (light colored) wood pattern. I can't quite imagine a bathroom with a (faux) wood floor, hence the thought about keeping the existing floor, and hence the worry about the seams between the existing and the new floor.

Yeah, agree that something needs to be done soon, keep the advice coming!

I would go ahead and work with a laminate or a vinyl plank. Remove the old vinyl (it is done....the seams have been disturbed many times - they are shouldn't be repaired). If you want it in the kitchen, you should be looking at vinyl planks. Laminate doesn't like kitchens.

If this is nice and you like the colour in the bathroom, you can leave it. Closets should be changed out to the new flooring. It all comes down to how level/even those subfloors are. The term you are looking for is "fibre board". That is VERY common, low-grade underlay for carpet and old vinyl.

The seam that is pulling up will help determine "full spread glue" vs. "perimeter". Go ahead and lift up that seam. If it pulls away easily = perimeter glue. If it is REALLY STUCK within 1/2" of the seam, you are probably looking at a full spread. Full spread glue down sheet vinyl is not so easy to pull up. Often times the SUBFLOOR is cut and pulled up WITH IT. Making everything a little easier to remove. A professional flooring installer can handle pulling up this vinyl without any problem. A homeowner might not have the tools to remove full spread adhesive vinyl sheet. Getting the fibre board to pull up with the old floor has a few tricks to it.

It sounds more expensive to do it this way...but it removes the PAIN and the HASSLE of that stupid fibre board. Very few floors are allowed over top of that stuff...which is why getting rid of it is not a bad idea.

I went to the basement to shoot the pictures below of the two different subfloors. The first subfloor is apparently plywood, although I am surprised that an exterior plywood material is used for an interior subfloor. The second subfloor has a stamp 'WAFERWELD SUBFLOOR T&G', not sure what material it is, waferboard? There is both carpet and sheet vinyl flooring on the two different subfloors.

I could pull-up the seam rather easily, hence it appears to be perimeter glue which makes it easy to remove the sheet vinyl floor without pulling up the subfloor. I would nonetheless hire a professional though, I am not very handy.

Is vinyl plank more expensive than sheet vinyl or laminate? One of the things I do like with the existing sheet vinyl flooring is that it forms a big expanse from front door to almost the back of the house, which provides a spacious and interconnected feel at the same time. Hence, I like to use the same material for the kitchen as for the rest of the flooring (except for the carpeted rooms) if it is not too expensive.

What you see from below, will not be what you see from above. A subfloor is made of two layers. The bottom layer is attached to the joists (and visible from below) and the top layer (known as the underlayment....because it lays UNDER the floor) is going to be another type of material. You won't know what that top layer is until you remove the vinyl or you can find a floor heat vent where you can view the cross sections of the floor.

If you like sheet material, then go for it. There are some very handsome sheet vinyl or sheet lino out there. If you work with a sheet product, you might want to replace everything that is covered in the original stuff.

Good news from looking at floor heat vents, although the bottom layers of the subfloor are different, the top layer appears to be plywood throughout.

I am still exploring my options, sheet or otherwise. I like the uniform look of my present flooring over a large area and whatever the replacement is (sheet or otherwise) it has to have the uniform look, it does not necessarily have to be sheet. You said vinyl planks for the kitchen, if so then it should be vinyl planks throughout the large area (except may be for the bathroom and closet that are closed off with doors)

I have clothes washer and dryer on the ground floor. Do they like vinyl planks too?

Thanks for the patience!

Vinyl planks are vinyl. Vinyl is allowed in bathrooms, laundry rooms, closets, etc. If you like sheet, go with sheet. If you like vinyl planks, go with planks. Vinyl is water proof and that's what you need for laundry, bath and kitchen. Whoever you get to that "water proof" is up to you (ie. sheet vs. vinyl plank).

You appear to be driven by aesthetics. The look of a continuous floor is very important to you. So go ahead and start shopping for vinyl or lino that will get you that look. Laminates are not allowed in kitchens nor laundry rooms. That means you lose the continuous flooring if you look at laminate. That means we are down to vinyl - whether in sheets, planks or tiles - the choice is ultimately yours. You want continuous....so why leave old stuff in place that damages the "continuous look"? That is the ultimate question.

Yes, we
are driven by aesthetics, the boss in the house even more so than I am. It
looks like we are down to vinyl planks with light colored wood look for the large area including hallway, kitchen, and laundry room. As I
understand it, vinyl planks do not involve glue, whereas sheet and tile do.

We still
like to keep the existing sheet vinyl in the bathroom if possible. Can the seam
with vinyl planks be nicely done, durable and good looking? I trust that the
transition from vinyl planks to carpet is routine workmanship?

There won't be a "seam" if you use vinyl planks. There will be a TRANSITION (a little plastic hump between the two floors) even with the vinyl floors.

And vinyl planks come in "loose lay", "Click together" and "glue down"....so there are many ways to get this done.

Even if you went with a sheet material (again) you would NOT use a chemical/heat seam between the two products. You would still use a transition. You do not heat weld/chemical seam two different products together like that...especially when there is more than a decade of time between the manufacturing dates.

If you want to leave the existing sheet in a few places, you will have to learn to like transitions. Have fun. Please go shopping at a local flooring store for more suggestions. You won't know what is out there until you go out and visit some stores.