We have a 80yr old house with original oak flooring nailed to the old floor boards.

ARE ANY OF THESES METHODS GOING TO WORK?:

1. rip up old flooring and screw down 5/8" sub floor and then lay new floors (not wanting to do, too much time and $)
2. lay 1/2" subfloor overtop of existing floors and then lay new floors on top.
3. lay new hardwood over old hardwood (keeping in mind that the old hardwood is on floorboards)

We dont care about squeaks and such, just as long as it stays put.

Also if laying over top of old floors, do you have to lay it in the opposite direction of the current boards? Cause we want to keep it in the same direction.

If you go directly over the existing, the new must run the opposite direction of the existing.

I like your option one the best, but if original sub-floor is reasonably sound, then I would substitute 3/8th inch plywood as a means to reduce costs somewhat.
Option two would work, but you would be un-neccessarily raising the floor a great deal and would involve a lot of door adjustments, etc.
Option three makes my queasy, never liked the idea of overlaying new hardwood directly over old, so am not going to endorse that one.

Actually we only have two doors to raise and cut. And I've also looking into these undercut saws which would make raising baseboards and moulding a snap (or at least I think).

So option # 2 would work??? what if we used 3/8" or 1/4" plywood over top of old floors to lower the height a bit more? The only reason I would lay the plywood over top of the exisiting floor is to run the wood the same direction as the old floor. I know hardwood over hardwood is bad if it runs in the same direction.

We really really don't want to go through the hassel of ripping up the old floor. it would mean removing kitchen cabnets, radiators, and be super messy and would have to rent a disposal bin.

I have considered all of your reasons for leaving the old hardwood in place. However, I have found when nailing through old existing hardwood, even if new plywood is installed over it, the old dry boards split and cause massive squeaking which cannot be remedied.

Ok, so get this. I just got a quote to remove the radiators (8 of them) on our main floor and the guy quoted me $250 per rad to take out and $250 per rad to put back in! That's $500 per rad x 8. $4000! does that seem reasonable? One thing to note is that we have the old cast iron rads that only have 1 shot off valve, so they would have to drain the system and cut the pipes, refit with a 2nd valve.

And this is why I dont want to remove the floors! hahha.

so is there any clean way of cutting around the rads? I've been trying to look for pictures online that showed nicely worked around radiators but couldnt find anything.

Cut the floor out around the rads, build three sided covers that sit near the edge of the new floor, paint to match your trim, or finish to match your floor. These will look better than the rads, even at the worst of times. Wood framed, ventilation access, many styles.

Great idea. For some reason I never even thought of rad covers. They would hide it all and look nice.

So once last question. You mentioned that the old boards underneath will create massive squeaking if going the route of laying 1/2" plywood over top of old floors. I dont mind a bit of squeaking, i'm just more concerned that the new floors will stay down for good. I dont want anything poping up or gapping. Would this be an issue?

The floor will not come up for any installation issue caused by the existance of the old flooring under there.
Should last as long as the old floor did.

Ok, well I think my questions have been addressed. thanks again. I think I may try and keep the exisitng floor and layover top of it with 1/2" plywood. The house is close to 100yrs old so a bunch of squeaks is probably suited for the house. lol. Squeaking is really a non issue for me. And we will be sure to use rad covers. that will be a cost saver for sure!

Another option would be to use a 3/8 or 1/2 plywood underlayment and go with a 5/16" solid or product glued or stapled to the UL. Drastically helps with height issues.

If you lay a 3/4 product directly over the existing subfloor you can also install it on a diagonal.

IMO, most squeaks in very old floors are from the solid sub flooring boards. I have found few hardwood floors that actually squeak. I have found many sub floors that do. By removing the old, original hardwood flooring, it allows one to fix sub floor squeaking. Sub floor squeaks can be repaired from below IF you have access to the floor joists. But it is way more labor intensive that way. Here is a real life example:

I have a friend who is a realtor. He bought an older home built in the early 1950's. The house is a single story with a basement under one part of it. The rest is crawl space. The subflooring is 1 x 6 doug fir planks laid on a diagonal and nailed to joists 16" oc. Over that are very nice 5/16" top nailed strip floors with apron/borders. So he asks me what it would cost to refinish them ( they needed it ) but he's complaining about all the squeaks, creaking and popping noises. I had to explain that the noise was coming from the old sub floor boards working loose over the years. The only options were to:
1) do nothing and live with the noises.
2) locate the floor joists and face nail through the strip flooring into the joists with #8 casing nails. Then fill those large holes during the refinish. This would eliminate 75 to 90% of the noise but not all. And the puttied holes would be somewhat noticeable.
3) Remove the flooring and repair the subfloor. Install new flooring.
4) Attempt to fix the squeaking from below by screwing L shaped metal channels along side the joists then into the subflooring. Not a problem in the basement area. Big hassle in the crawl space area.

We as installers can sometimes get complaints about squeaking, noises floors. Many times, it is the subflooring and not the hardwood flooring. Fixing subfloor noises can be a real nightmare sometimes. The customer needs to understand this is not included in a normal install and we need to charge extra for labor intensive sub floor repairs.