Wooden Woes

So we got those two boards down, and now we're worried that we might need to pull them back up again. Here's why:

Here's a sample room in my upstairs. The window is on the front of the house (down) and the door is on the top (or the side of the top, which is why I didn't draw it). The joists (heavy black lines) are going front to back with the house. For brevity's sake, let's call that vertical. You have several options when installing a wood floor. You can go vertical, horizontal, diagonal, or around the room in a sort of strange patterny thing. Mainly, people go vertical or horizontal. There are several factors that influence this decision. One is the direction of the joists. Ideally, you want to go across them. Another is the direction of the doors and windows. You want to go perpendicular to those. The room shape is another factor. You want the floor to go with the longest wall in the room, so it doesn't end up looking cramped. So you have three things you really want to take into account. Here are my options:

Okay, this is the room with the boards across the joists. You can see that they are perpendicular to the joists, but they are parallel to the door and window, and also they are perpendicular to the longest walls. That scores 1/3 in my book.

In this example, we have the boards laid vertically. They are parallel to the longest wall and perpendicular to doors and windows, but they are also parallel to the joists. That's 2/3 for this one.

Diagonal and patterny are also options, but they work best for large, open rooms without a lot of furniture in them. Also, the wife really doesn't like them, so that pretty much rules them out. Diagonal is really the only way to get a 3/3 score though, since you can be across the joists, and sort of fudge the doors and longest wall rules.

Apparently, the point for being perpendicular to joists is supposed to be weighted more heavily, which adds to the confusion. This is my understanding of why.

When you go across the joists with a board, it is fully supported from underneath. Actually, there's another layer in between the two, but I took it out for clarity. It's a piece of 3/4" OSB, for reference. It's a pretty standard thing, so it's under carpet, tile and hardwood floors alike.

When you go along the joists with a board, you can supposedly get warping and gapping over time. Not all the boards are actually over top of any joists, unlike what I have drawn above. Some are completely unsupported, and the consensus seems to be that they will start to dip over time, giving you a wavy floor. I don't know, though, whether this refers to an issue in modern houses made with modern materials or if this is mostly an issue in older houses made with solid wood joists of some unknown dimension, placed some unknown distance apart, and covered with wooden floorboards instead of OSB.

So, to my mind, this is what is being suggested:

That obviously doesn't make much sense. If the OSB is also bending, then why don't you notice a rippled effect in carpeted rooms after a number of years? The wood flooring, even if it's not over a joist, is still rigid, and will distribute the force across a wider area. I'm thinking that maybe the thing that happens is that the OSB does bend, but it's so incredibly slightly that you don't actually notice it in a carpeted room, but you would notice it in a room with a wood floor. That's pretty much all I can figure. I also don't know if this holds true for engineered wood floors, since they should be more stable than solid wood floors. I also don't know if this only holds true for finish-in-place wood floors, since they tend to have a smoother, more uninterrupted surface that might telegraph extremely slight changes taking place beneath. With a prefinished wood floor, would you notice the same effect, given that the boards are all a little beveled around the top?

Of course, as we have learned on this journey together, not all things in a house obey the laws of logic or physics. Sometimes they just do their own thing and you try your best to keep up.

That's it for now. I'll let you know what we decide when we figure it out. Thanks for reading!