I went to a structural engineering conference recently and lally columns were of particular concern. They talked a lot about rust on lally columns, steel lally columns that are filled with concrete in particular. If there is rust on the lally column, even at the bottom, it can reduce the strength of it up to 40%. That’s significant. They recommended lally column replacement if there is rust on it.
You have to break a hole in the floor, dig down, and pour concrete. What we are pouring is called a footing, it evens-out the pressure, because the slab is only 3 or 4 inches thick and it is not strong enough to support. Then we cut a lally column to the proper size and fit it in there. On top we put a very thick piece of steel with a cup welded to it, and the lally column fits in the cup.
This is not a DIY project. A homeowner can prevent rust by checking the lally columns yearly. If you see rust, wire brush it off, and use rust preventing paint to eliminate it. A little maintenance goes a long way.
For more information on lally columns, contact A1 Foundation Crack Repair.