will be having my house re-sided with either cedar lap siding or cedar
shingles (currently it has cedar shakes that are poorly installed (not
sufficient overlap.) I have several questions.

#1--the sheathing underneath is shiplap (looks like 1x8 boards). Is
this significantly less strong than plywood sheathing? Would it be
worth my effort to have a layer of plywood installed over the top of
this shiplap sheathing? Also, this shiplap sheathing is installed
horizontally...I've heard its supposed to be diagonal...is this a bad
thing?


#2 When the siding people are installing the siding (and possibly
plywood), how on earth can they avoid the posibility of piercing a wire
or plumbing fixture?

1 - Dunno, mine was horizontal and that does seem stronger. I wouldn't
mess with it, personally.

2 - Nails probably aren't long enough. Wiring hopefully is run down
the middle of the wall stud, and there shouldn't be any plumbing
running inside exterior walls (famous last words !).