Lally Column Video
Hi, I'm Tim Carter and I'm here at a new home construction site in New Hampshire. I want to show you a little structural thing. This is a lally column.
A lally column supports a lot of weight. Under the concrete floor, they poured a footer pad, then the concrete floors sits on top of that, then the lally column. This is what is happening with the column. At the top of the column is the structural header, but above that is a block of wood that touches the underneath of the subfloor. The reason that is important is once the house is built upstairs, there will be a post sitting on top of this block and lally column. This upper post will be supporting weight from the roof.
The upper post can't just sit on the subfloor. It would be too much weight for the floor. Direct load bearing all the way down to the ground below. You can see how that happens with the wood column above, solid subflooring, the support block above the support header, then the header and finally on to the lally column.
You have to be sure your bearing points are all properly supported all the way down.