Most homes are outfitted with 5" gutters and for a lot of those homes 5" of gutter just isnt enough. Either there is too much volume of water coming off the roof, the pitch is steep and its coming to fast, or you have multiple pitches coming together at a corner and overwhelming the gutter! Anytime water gets to the base of the home in large quantities its probably only a matter of time until that water finds its way into your basement. For most applications we recommend 6" gutters. While more costly(not a lot) in the short term the long term potential savings from not having a flooded basement makes 6" gutters a worthwhile investment to protect your home!