I recently found support posts in a crawl space that were not placed directly on the concrete piers. The posts are from 2-5 feet long and look fine but they are all sitting on a block of wood (2x6). One of the blocks of wood has taken on water and began to compress. Causing some very minor but noticeable sagging in the house.
How should this be fixed?
I don't really want to replace the entire post. Someone suggested a concrete block to replace the wood.
Support posts should be firmly attached to a concrete footer. A concrete block resting on the ground is NOT a footer. Lots of folks with post and beam houses use concrete blocks to support the posts because the blocks are cheap and easy to install, however the better way to do it is to install a proper concrete footing with an embedded galvanized steel bracket to support the posts. The design of the footer varies with region and soil type, but since you failed to mention where you are located and what kind of soil you are on, little more can be said at this point.
2-5ft? so some are 2 ' and some are 5'? sorry, didn't understand that. but i was thinking that a poured concrete footer with rebar is best like daniel suggest i only wanted to add that the footer should be below your frost line. in a crawl space, at least in my house, there is 2' between soil and floor, but the soil itself is still 2' above front line, so i would have to dig 2ft down (some mystical way) + depth of footer and THEN pour the concrete and the new post would be 4'.
"if you can't be handsome, at least you can be handy" -Redgreen