First there is the most obvious reason. If the gutters are full and the drains are plugged they defeat the purpose of having gutters in the first place.
Dry leaf build up is a major Fire Hazard
Debris collected in your gutters can act as a potential fire hazard. Embers from fires, including an outdoor BBQ, can travel long distances, if an ember lands in a gutter full of debris, it can ignite causing a house fire. All Australian Fire and Rescue Services recommend that gutters are cleaned regularly to reduce the risk of a house fire, especially during bushfire season.
Blocked gutters can cause serious water damage
When it rains, the water overflows at the blockage and leaks over the gutter. The overflowing water will either then travel into your home and cause substantial water damage to your roof, walls and floor or overflow to the outside causing large amounts of water to damage the landscape below.
Mould growth inside can cause serious health issues
If water is making its way inside your home it may only be coming in small amounts which aren’t noticed. This can cause mold to grow rapidly which may not be seen straight away. Mould spores travel through the air which can be a serious health issue.
Dirty gutters are a breeding ground for vermin and pests
Insects and vermin love living and breeding in debris filled gutters. If leaves, twigs and debris are allowed to gather, insects, rodents and other pests will nest. Mosquitoes love stagnant water. If your gutters are plugged they can be an oasis for mosquito larvae to grow and hatch. This can be detrimental to the health and well being of your family and pets as mosquitoes are known carriers of many diseases. Without regular cleaning, vermin can begin to invade your property.
Damp debris left in gutters can cause them to rot
If the drains are plugged, water could sit in the gutters for weeks. The gutter will eventually rot away as it isn’t designed to be wet for long periods of time. If you have wooden fascia, these areas can rot away as well. Gutter replacement can be very costly.
Weight of debris can damage the gutter system itself
Gutters require a certain angle to drain properly. Gutters which fill up with debris become full and heavy will eventually distort the proper angle of the gutter or even cause it to fall off. This can usually only be fixed by replacing the gutter which can be costly.