Spider webs are stronger then steel, in fact it is 5 times stronger than steel by weight. If you were to spin a web into a 1/4" rope it would lift a 7000 pound truck off the ground, or 21 sumo wrestlers of an average weight of 330 pounds.

So you think you can wash off a spider web with a garden hose? Ah yes.

A regular power washer wont remove those spider webs either. Only way is to get up on a ladder (or have someone else do that, if you are not able) and use a bristle type brush, to get rid of them. A dry brush works better to get them off, than a wet one.