The problems with the old house

The old house was renovated and added to in 1999, just before we bought it. Although they did an okay job, there were some inherent problems that a simple reno could not fix. The original, 1960's 20 x 30 ranch was on a concrete slab. The land slopes towards the house and the water table is extremely high. When it rained hard we would often get water seeping in. In the reno they had put some drainage on the south and west sides, but it was not very effective (even after I cleaned out the plants that grew into it), and there was no protection on the lake side and north side.

This photo shows a result: on the north side, next to the door and a downspout that sometimes leaked, the door frame is rotted and mold is creeping up the wall. I tried caulking outside, but it only slowed it down a bit.

The concrete slab is cold all year. This is merely unpleasant in winter, but in summer when the humidity is high it caused condensation problems in the kitchen with its tile floors. Running a fan at floor level helped but needed a lot of attention (repositioning frequently).

The house was also poorly insulated, particularly the new addition, which got very hot in summer (big east windows) and cold in winter.
The layout was not great either: the entrance was awkwardly positioned, and the space was not efficiently used.