I'm building a fort for my kids out of wood, 8 foot by 8 foot and trying to work out how to make it last. I can't get treated wood, and apparently untreated wood rots within a year of ground contact even if painted.
Can I make a base out of 3 inch pipe, with 2 foot legs concreted into the ground and then build my fort on it? Perhaps have the base raised a couple of inches off ground? How long could I expect it to last. I don't want to (can't afford to) build a proper foundation, just concrete in the legs so it's solid.
We get a LOT of rain here, like a monsoon season and cyclone prone, so I need it solid as it will be 15 foot tall on an 8 foot square base. Although in the event of a cyclone I'd probably unbolt it from the base and lay it down.
Best Answer
You could build big concrete posts, maybe 12" in diameter, up about 12" above ground level, and use metal post bases to keep the wood off the concrete. Be sure to treat the end grain and base of the post with the best preservative you have available, and it ought to hold up pretty well.
In the comments you mention you're in the mid Pacific. Without pressure treated available, keep in mind that some species are far more rot resistant than others. The people selling lumber may be able to help suggest what will work best. Farmers usually know, too. Some of the most rot resistant woods are tropicals that would be very expensive exotics where I am, but they may be affordable where you are.
Sometimes small utility poles are at a decent price, they are treated for direct embedment in post holes. Setting a pole is doable with nothing more than a shovel if you can hand dig the necessary depth.