House is cabin construction 2x4's. Dirt floor. Main support piers in the center of the house are sunk concrete, but the beams are sagging all over. Center support piers are reasonable.

I used jackposts on concrete blocks between the center support pier and outside wall. The problem was crawlspace was wet so the blocks sunk. I have remedied most of the wet problem.

So the right way to do this is to dig down 2 feet and sink some concrete, then jackposts under the sagging part of the beam. (ok should be wood pier...) I was told only screw the jackpost say 1 inch a week till its level.

Are there alternatives to sinking concrete?

It's rather cold here now and the less I have to be under the house, the better.


  • I don’t understand 1) you say “dirt floor” then say “crawl space is wet”. 2) What is reasonable about center support piers? 3) How large is the house? Is it all sagging? ...sagging uniformly? Is it one story only? 4) Can equipment get inside the house on the dirt floor? 5) Are there pile drivers available? ...vibration piles used in your area? 6) location? – Lee Sam Jan 20 at 4:17
  • With the floors sagging jack posts over time is a good idea. If your pier blocks continue setting you need additional ones or larger ones. – Ed Beal Jan 20 at 16:54
  • The immediate problem is fix the floor under the woodstove so I can put an airtight stove in. How big / long on 6x6 pressure treated? I was thinking several 2ftx2ft concrete blocks - but that could settle too. I suppose I could screw mount the jackpost to the beam... – House DiY Jan 21 at 7:13
  • Can I dig a hole and fill with gravel, then put a paver on top, then the jackpost? 4 foot jackpost at most. – House DiY Jan 21 at 15:20
  • Lee Sam - 1) you say “dirt floor” then say “crawl space is wet”. Water was literally streaming down the driveway downhill into the crawl space (with a dirt floor). Mostly fixed now. I dug a trench in front of house. 2) No apparent major sinking and dryer 3) Very small. This beam is 30 feet at most. It is slabbed 2x4. >Is it all sagging? ...sagging uniformly? It sags from the center to the outer side piers on both sides of center support pier >Is it one story only? Yes 4) Unlikely 5) No. 6) Northeast – House DiY Jan 22 at 16:30

I don't think digging a deeper hole into wet ground is going to help you. You need more surface area. I would form and pour a footing two to three times the area of the support you currently have. If it is too cold to pour, then I would simply put the jack on some 4x4 or 4x6. If you are sure you will fix it in the spring, it doesn't matter what kind of lumber you use. If you may forget it, or it becomes a 'git'er later', then use pressure treat or ground contact lumber.

  • The main moisture problem is likely solved by trench in front of house. Stops runoff from steep driveway rolling into basement – House DiY Jan 21 at 7:14

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