First, they almost certainly would make their cabins from green wood. It's much easier to hew a log into a building timber when it's green, and if we presume they were working with hand tools to build their cabin, saving time and effort was a big deal. Just the thought of trying to mortise very dry white oak makes me tired.

They had a few ways they could keep their cabins from rotting or bein attacked by insects. First, they might be able to choose the wood. This would not be simple. Locust is very rot-resistant, poplar and pine less so, but in the southern Appalachians tulip poplar will give you perfectly straight clear logs of great length and size, and the wood works easily. Locust does not, and tends to be smaller and knotty. Because green logs are heavy things to move, it is not surprising that they'd try to work with what was nearby. If they were lucky, they'd have some oak, chestnut and walnut around them.

Second, they would peel the logs. The bark of a tree has a lot more food value to a bug or a fungus than the high-cellulose wood itself, and so logs would be stripped:. There was even a tool called a barking spud to do that job, though if the builder was lucky enough to be working in the spring the bark might peel off very graciously with a chisel.

Once peeled, if the wood was kept dry it was not going to rot. Setting the corners of the cabin on stones , to get the logs off the ground, was a simple way to do some of that- but if there was a dirt floor or puncheon floor ( planks set directly on the ground) that meant they needed more rocks and fill, to keep out the winter winds. For both rot and insects, there was also whitewash. Lime ( calcium carbonate) in water, sometimes with some milk added for adhesion, would deter wood-boring beetles and fungi. It also would make the cabin look like more like the nice houses of the folks in the city.

But there was a range of what people on the frontier would attempt. Traders might knock together something very basic, just to get through a few winters, and poor squatters might do the same, hoping to loot their land to make not only a cabin but get oak bark for selling to tanners, split wood for barrel staves and fence rails, make wood ash though which they could leach water to make saleable lye and nitrates, and grow enough corn between the stumps to feed their existence. Someone buying an existing homestead from those poor squatters ( because the first wave of settlers often had to move on, after a few years of looting) , someone who had more resources, might build a more solid, bigger cabin...or, buy two cabins already built and use the logs for another, nicer one.