Am I the only one who thinks Beck’s posts read like a sitcom plot?
I would totally watch that show
We’ve got 80+ year old hard pine floors in the old part of the house, which is a log cabin that cracks and squeaks by itself with changes in temperature and humidity. Those floors are far sturdier than any modern hardwood flooring I’ve encountered. I’m sure the OP’s 150 year old house wasn’t built with modern laminated hardwood flooring that is most commonly found in modern homes. The old hardwood planks are likely far thicker than that and nailed directly to joists underneath as I assume yours would be also. Though if there is an underlayment it wouldn’t be plywood or similar materials, more likely diagonal planking, but at 150 years old or 108 years old like yours the flooring is probably solid T&G planks right on top of the joists.
In the end, some bracing, shimming, screws or ring shank nails may firm up the floor but cracking noises aren’t going to disappear for the next 100 years.
All of the houses I have lived in have had squeaky floors. Unless something starts to shake or bulge or noticeably detach I just ignore it.
I am considering doing something with the bathroom only because the 50 year old vinyl flooring needs replaced. I imagine some of the wood will need updated once that is removed. It’s on my to do list.
My current house is almost 100 years old and the squeaks are telling me it’s getting old.
Hopefully I will be out of there in a year or two and the next owners can take on the squeaking…and everything else I may have not kept up with. I am just getting too old and tired to deal with home maintenance and upkeep at my age.
I had this issue in my house. Turned out to be the nails that held the subfloor to the floor joists were slowly pulling upward. I simply replaced the nails with drywall-type screws.
Ours was originally built and occupied by the owner of a local lumber company, so they didn’t skimp on construction. It has 2" (actual) random width rough sawn poplar subflooring atop 2x12 (actual) joists. The hardwood finish flooring is nailed into this subfloor, not directly to the joists. This is the usual technique in our area.
My reference upthread to the hardwood joinery as mortise & tenon was obviously in error, it is in fact, tongue & groove.
This was my assumption as well, hence my suggestions. However, if it does have a subfloor…
… this might or might not help. If the squeaking is due to from slack in the area where it is nailed, it’s probable that the subfloor is deflecting right along with the hardwood flooring and might continue despite being screwed together (depending, of course, on how many screws are placed). If you are going to be underneath the flooring anyway, the best bet would bracing, imo. Graphite and baby powder might help, but is a temporary fix.
Yeah, I picture people slipping and sliding all over this now ‘frosted’ covering. Probably sneezing too. 
How thick is the hardwood finish flooring? I’m curious about these things. Our floors are slightly thicker than 1-1/2". The joists are 2x10s on 5x10 beam, actual measurements. It was all factory milled from cedar in a kit. The structure was designed to maximize the output from each cedar tree so they weren’t going to use common lumber measurements.
I assumed that’s what you meant. After all, it is a kind mortise and tenon joint, just not for the usual purpose of joining wood at right angles.
Old houses can be fun and interesting but like @Ellecram I’m too old and tired to be dealing with the work involved.
I think the original was 1". Due to several refinishes (heavy sanding) it now is approximately 3/4".
Me three.
14 steps from basement to 1st floor, 17 from 1st to 2d floor, 8 from street to 1st, 5 from basement down to back yard, 15 from deck @ 1st to patio below, then a bunch of stonework ups and downs in the “gardens”.
Due to spinal cord damage, I’ve lost control of my left leg from the hip down and the right side isn’t far behind…needless to say, my sense of balance is gone.
In the past 8 months I’ve made a hobby out of falling down all these damn stairs. So far, the only breaks I’ve suffered are both big toes, left ankle, left foot, and four ribs along with various cuts and contusions…but nothing serious.
Anyone wish to buy a home with a panoramic view of the city?
Forgot to mention:
Just finished cleaning all the gutters on our place yesterday. As slow as I move anymore, it takes the better part of two days creeping around with a 24’ extension ladder in the back, and a 20’ in the front.
I made it through the entire ordeal without incident, then while retracting the ladder to finish it up, I lost my balance and the ladder whooped my ass…we both crashed to the ground, me faceplanting on the sidewalk with the ladder on top of me. Nothing broken but my pride and a large terra cotta planter.
BTW: Thinking of lowering the asking price.
I know this is FQ, but … 
I’m so sorry. I hope all that nonsense is behind you. As I always tell my ‘older’ mother, who lives in a three-story house: falls are the enemy!
And just so you know? There are other hobbies 
My life could fill at least 3 seasons of a sitcom.
But, really the baby powder worked. I looked around for some other thing to grease the cogs of my squeakish floors. Alas, nothing was located.
The kids loved the slippy floors. It was a sock dance party when I reapplied powder. There was some sneezing, mostly my old Rat Terrier.
This could be a very long term slow change that has finally produced a first noticeable outcome. Many areas are experiencing a change in the averages of temperature, humidity and other things. Wood takes in and lets out moisture in cycles. It varies greatly as to outside conditions and the type and size of the wood. If the average cycle of humidity has changed enough in your area, the wood may have become generally drier and to a greater depth. Or the opposite may have happened. It is holding more moisture. If it is drier, it will shrink more. Internal saps may fully hardened. Shrunken boards move more. Maybe suddenly cut loose from a neighbour and snap. Then settle back in slowly till you next tread on it. Or swollen boards arch up and also snap down when trod on.
If the floor is unfinished, maybe get it oiled. I have no suggestion for a good product. But an oiled wood is less susceptible to shape change with humidity change. If it is finished and you like it, maybe it is accessible from below?
Others mentioned joist issues. This can also be due to sustained difference in humidity. Being such large pieces, one might just leave them be and oil and shim the floor boards instead.
I am no expert at all. But I lived in and renovated a 100 plus year old home. Much of the wood had become rock hard. Taking up much of the flooring had the wood shattering rather than bending and splitting.
Just my guess on this.
Yeah, I absolutely love this house. However, I do sleep in a day bed under the stairs most nights because I have a knee that needs replaced.
I don’t remember who said it above, but there are no visible nails in this floor.