DIYbanter - View Single Post - Can you place anchors in a concrete slab at a later date?

El Barto

(Chris Lewis) wrote:

Remember, this isn't a lifting load (w.r.t. the big dig accident
a few days ago), so that's not going to happen. But strong
winds are perfectly capable of moving structures like this,
and just picking up lag screws and anchors out of a hardware
store bin _can_ be a mistake if you don't install them properly.

Actually, it's the lifting forces imparted by high winds that the
anchors need to handle.

If the structure is tied together (e.g., with hurricane clips,) then
high winds going over the roof will create suction and uplift forces.
These must be withstood by the anchors, or the scructure will lift off
its foundations. (If the scructure isn't tied together, then the roof
will just fly off.)

The other thing that happens is that lateral wind forces on one side
of the scructure will tend to push that wall inward, rotating it
around the sill plate. This will create a lot of upward force on the
anchors, as the wall is essentially a large lever. This can be
mitigated somewhat by using sheathing (OSB, plywood, etc.) around the
outside of the structure, or at least at the corners, to counteract
the racking forces.