Question
I have three redwood trees that I planted for privacy between my house and the neighbors house. I live in a two story and want to know if I can top them at my eve height to keep debris off my roof and out of the gutters? Also, they are about 6 feet from the house. (I know, too close.) But, would like to trim the branches off at about 3 feet from the house. Would they fill in to make a "hedge"?

Answer
It will depend on how tall the trees are now whether you can cut them to eye level. It is never good to prune more than 25 % of the top of a conifer. The growing part of the tree is the terminal bud and conifer trees can be pruned to keep them smaller ala Christmas trees. But this pruning is done when the tree is young and not above a two story house, In your case i am not sure it will work well.
The side branches can be prune or trimmed to keep them from hitting the house. The ones on the house side could be pruned back further if needed.