Those are some amazing before and after shots! Even here in Orange, Texas about 45 minutes from the coast I got several consecutive nights in the teens. It knocked most of the leaves off my Ponderosa Lemons and it froze a blood orange almost to the ground. The following summer was a drought and I didn't even bother to water the orange. I was totally amazed when it started sprouting leaves when it started raining again. Maybe it's a sign I planted it too deep but I had a mixture of trifoliate orange and blood orange leaves. I pruned out the trifoliate growth and the tree is still growing. Hoping to get some fruit some day since it is apparently quite capable of handling local weather extremes. The blood orange is the little tree on the left. I'm going to have to invest in a new camera....or maybe a tripod if I'm starting to get shaky hands in my older age.

I planted four ceanothus between 18 and 20 years ago. Two were the white thrysiflorus (or however it is correctly spelled) and two of the 'Ray Hartman' variety. Both of the Ray's are gone now--they were never watered after the first year or so, but as I pruned they started to die back, the more I pruned the more they died back. One of the white flowered ones did not make it through a bad frost we had the first year or so, but the other has been doing fine until a couple years ago when the die back started with that one, too. As awful as it looks, I am reluctant to cut the dead branch ends off, except that it does seem to stimulate growth from farther down the trunk/limbs. My thought was that I must be spreading some dread virus by not cleaning my cutting tools well enough after cutting another infected plant. My wax myrtles are doing the same thing, although the problem does not appear to be terminal with those. (well, the die back is "terminal"as in at the ends of the branches, but not fatal.)

The concrete slab floor should come no higher than the top of the existing foundation wall. This would require a step down immediately as you exited the existing structure. If you don't like that arrangement, then use a framed floor system rather than a concrete slab, The framing will then be at the level of the existing rim/box joists with no step down needed....and you can adequately insulate the floor between the joists as required.

I see this worked...could it be too many pictures, I attached 5 I think.