One of the most common questions I get is “How should I attach my gutters”? Well, there are two common ways to attach your new seamless gutters. Spike/Ferrule or Hidden Hangers. Both standard fasteners work well for flat fascia, but what about angled fascia? 
One of the first things I advise my customers to do is to pick a company with a lifetime workmanship warranty so the choice is always made easier. While both types of fasteners have advantages and disadvantages, knowing that your company will take care of any issues that come up will help you choose which type of fastener will best fit your situation.
Hidden hangers offer a more stylish look with no visible nail heads along the top edge and offer ease of maintenance, but installing on angled fascia requires some means of support such as adding a wedge behind the gutter to keep it perpendicular to the roof and to hold it level in a heavy rain.
Wedges are a triangular piece of aluminum that is placed behind the seamless gutter to add support and keep your gutter nice and level and to prevent sagging. Some applications with a severely angled fascia or 3/4 board nailers or will require use of spike/ferrules or special heavy duty “screw-in” hangers. As mentioned before before make sure you have a good warranty and experienced installers to make the correct recommendation for your Seamless Gutter application.