On 2008-05-03, wrote:

I have vertical redwood siding on one side of my house and I've
found that there's a sizeable gap between the bottom edge and the
wall that mice have been using to get into my house. The gap was
large enough (1") that I wonder if it's supposed to be there for
ventilation.

Ventiliation behind siding is good, particularly if you get a lot of
wind driven rain. The free space provides a capillary break so any
water that penetrates the siding can drain down instead of wetting the
weather barrier. If you need to fill the gap at the bottom, there are
various products available, like those at www.coravent.com (just to
pick a random manufacturer).

Cheers, Wayne