The foam allows water to pass through it into the gutter while blocking leaves flowers twigs and other debris from entering the gutter system.
Reasons not to plastic gutter.
Foam gutter guards come in long pieces of dense triangular or thinner arch shaped foam designed to fit inside gutters.
Most plastic is also susceptible to the cold so if you live in a climate that gets extremely frigid winters or you opt for lighter grades of vinyl you could find your gutters cracking in the middle of winter just due to the cold.
Plus ladders will not dent the material and any blemishes on the surface will not be visible.
1 debris clogging up the gutter and or downspout flow leaves shingle granules sticks from broken tree limbs even plastic bags all of them frequently find their way into your gutters.
While not a permanent fix you can generally get another season or two out of the gutters as long as the damage isn t extensive by applying a silicone or rubber gutter caulk or sealant.
Upvc is though highly resistant to water and will not freeze or corrode over time.
You simply insert the pre cut pieces inside the gutters.
Foam is easier to install.
It s the most common reason for overflowing gutters.