I am replacing an entrance with one like this three-pane design with a door in the middle and two side panels:
The door will swing over a concrete slab inside, requiring about a 1 inch raise above the slab to provide space to clear a foot mat and tiles. The entire assembly is about 6ft wide.
Currently there is a piece of 1x6 to provide some of the raise. I used thinset to fill the unevenness of the slab, applied a sill guard and then the 1x6. There is no vertical room for a 2x6.
There is also about 0.5in of additional horizontal shimming needed to level the threshold. That gap and shim is currently between the 1x6 and the door's threshold.
The studs in the opening are anchored sideways into concrete foundation, and the jamb will be screwed & shimmed to these studs.
The threshold is aluminum. At how many spots does it require shimming (between the threshold and the 1x6), and does it require cement / thinset between shims to prevent bending?
Should the threshold be anchored to the foundation under it, and if so, how? Or is the sideways fastening of the jamb into the studs sufficient for the threshold?
I am concerned that door slamming may put too much lateral force on the threshold and too much stress on the lower jamb fasteners.
I could anchor the 1x6 with anchor screws, but the threshold can still move freely. I don't believe the adhesion of thinset or cement is the appropriate remedy for these lateral forces. But maybe it is?
The opening over foundation is much like this one
Except that the inner jambs for the door obviously cannot be fastened to the studs, and so lateral slamming forces transfer through the treshold and the top jamb sideways into studs and into the header.