This has to be 1982 when Clare turned 4 and Drew is about 9 months old.
It is confounding to look at old slides out of order and find that just looking at the age of children can be confusing when trying to determine years and dates. The construction was dated about 1983 and here is evidence that in 1982 when Clare got the swingset for her 4th birthday, the house was in it’s first stage and apparently closed in. The new construction must then have begun after Christmas of this year. Also Kristen visited when she was 15 and as she was born in 1967 (summer of love) and turned 40 this year (we love you Kris!) that would be fall of 1982. So 1983 is the year construction on the addition was started. Whew!