Making sure the gutter system is properly installed is key to preventing water from damaging your fascia board.
How to tell if fascia board is level for gutters.
Climb your ladder so you can reach the ends of your rafters and hoist the board into place.
A loose gutter system can also damage your boards as it pulls away from the wood.
Check this by holding a level against the bottom edge.
Snap a chalk line to indicate the top of the gutter.
If your fascia boards are level you can use them as a reference for sloping the gutters.
If they aren t level adjust the string line until a level aligned with it shows a slight slope.
Also make sure your gutter piping is firmly attached to your fascia board.
Gutters should have a small amount of fall toward the downspout or be level at the very least.
Thankfully there are ways to counter this damage.