This is a good site for genral information about building near trees.
For more specific information about redwoods and your part of California, try Google with the key words "tree construction damage".
In genral, tree roots have a zone of rapid taper, which is located in a radius around the tree about 5 to 8 times the diameter of the trunk. Cutting, burying, or compacting these roots can cause decay to quickly enter the lower trunk, creating a hazard. I would state that distance (5 to 8 times tree diameter) as an absolute minimum for building near a tree that could become a substantial hazard.
Tall trees also have the potential to lose tops or branches during extreme weather conditions, so the proximity, lean and condition of the trees near a structure should be considered, as well as its' exposure to winds based on surrounding topogrphy.
Because of the extremely high value of large trees, both to proprety value and society, and the potential for creating a hazardous situation, I reccomend bringing in an
ASCA certified Consulting Arborist, at the planning stage of the project.
