I've been thinking about wood, so we'll see where that takes us. There are wood things you should pay attention to when you buy a home.
The lumber in an old home can be amazing. A two by four was really 2 inches by four inches unlike the today's 1 and a half inch by 3 and a half inch. I have seen old homes with oak or walnut floor joists! Not common however.
So why are old homes so often uneven? There are lots of possibilties.
In our area, your wood house probably sits on a concrete or limestone foundation. Cool concrete attracts moisture and wood soaks it up. In new homes it is code that any wood that is in contact with concrete is treated.
What about old homes? Check for rot in places that could be moist. Some old homes have cement between the rim(floor) joists which can cause a problem. Also wood posts on damp cement floors can rot. Partial basements in older homes can be chronically damp.
When you are in the house take your car key and poke the wood in these places, Random floor joists, the ends of the floor joists where they rest on the foundation and support posts. While you're at it check the exterior window trim in the same way, especially towards the bottom.
There are usually ways to deal with rotted floor joists and the like, but it would be nice to notice this before you write a purchase agreement.
In the old days, especially before 1900, people had more faith in their lumber. Sure the old two by fours might have been beefy, but they had to span ridiculous distnaces in many roofs. Old neighborhoods are full of homes with sagging roofs that you don't notice until you start looking.
A Saint Paul lumber yard used to have pictures on the wall of old Saint Paul homes being built. The homes at that time were "balloon framed" meaning one two by four went from the foundation to the second floor. The photos showed 2x4's sticking high into the air beyond the second story waiting to be trimmed off.
The older your home, the fewer bulding codes there where at the time it was built. When you are looking at homes note the dimension of the floor and ceiling joists. It would be nice if they were 2 x 8's or more and 16 inch on center.
If you are looking at a house with attic or "expansion" space ask your inspector if the floor joists in the attic can handle the load.
I was in a big old house last fall that had 2 x 4 floor joists 24 inches on center. It was sagging under 100+ years of its own weight and needed first aid.
There is another thing that leads to sagging in an old house that is more common than the first two. Look at the plumbing and heating and how it was run. Often, sometime in the past, a furnace man or plumber has simply notched or completely cut away important parts of an old house to run pipes and ducts.
The good news is most of these items can be repaired, in some cases you may just leave it alone and call it character.Thats it for now.