Woodpeckers usually cause two kinds of problems on buildings. Since they hammer on hollow trees and other resonant objects to claim their territories, if they find a nice sounding board on your house, you may have to put up netting or another physical barrier to keep the birds away. A more serious problem occurs when woodpeckers find that your wood siding is full of carpenter bees or other insects and decide that lots of drilling and excavating is the best way to get to that food. Check to make sure you don’t have an insect infestation in your siding, and check out your local extension service or the Cornell Lab of Ornithology for additional information on visual deterrents and physical barriers you can put up to keep the woodpeckers away.