A sagging eavestrough is a symptom, and cleaning fixes only some of the causes behind it. Here are the common causes, what a sag puts at risk, and a four-step test to tell whether a clean will be enough.
In This Article
Causes of a sag, and what fixes each
| What you see | Likely cause | Will cleaning fix it? |
|---|---|---|
| A dip between hangers that straightens once the trough is empty | Weight of wet debris and standing water | Often, though repeated sagging points to too few hangers |
| The run stays low after cleaning | Bent metal, or hangers that have loosened or slipped | No. It needs re-hanging or a new section |
| A gap between the trough and the fascia, with fasteners showing or lifted | Spikes or ferrules pulled out by freeze-thaw and wood movement | No. It needs re-fastening with proper hangers |
| Dark, soft or peeling fascia behind the trough | Rot from long-term overflow, so fasteners have nothing to grip | No. Repair the fascia first, then re-hang |
| A run bowed outward after winter | Ice or snow load pushing on the trough | No. It may need straightening or replacing |
| A crushed or dented spot near a ladder position | Ladder pressure on thin metal | No. It is cosmetic, or a weak point to watch |
| Low spots from the day it was installed | Poor slope, or settlement of the house | No. It needs adjusting to the right pitch |
Aluminum is light and soft, so it shows sags and dents earlier than heavier metals. Long unsupported spans sag sooner too.
How winter finishes what fall started
Most sags in Southern Ontario are built over a single fall and winter. Wet leaves stay in the trough after the last dry day. Rain and melting snow fill the gaps between them, and the whole load hangs from a few fasteners. Freeze-thaw cycles are common from November to April, so that water freezes, expands against the seams and hangers, thaws and freezes again. Each cycle loosens the grip of a spike in the fascia a little more.
By March the trough carries dead weight and holds a ridge of ice on the outer edge, and the fasteners that held it up in October are a fraction as tight. That is why a run that looked straight in the fall can sag by spring. It also explains why the fix that lasts is a clear trough and sound fasteners, not one or the other.
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What a sag puts at risk
- Standing water. A low spot holds water after every rain, so debris stays wet and seedlings sprout. In winter that pool freezes and pulls the run down further.
- Fascia and soffit. Water that spills over the back of a tilted trough soaks the boards behind it. How clogged gutters damage fascia boards shows how quickly the wood softens.
- The foundation side. A sagging run overflows in the wrong places and soaks the same strip of soil beside the house.
- People and property below. A trough that lets go can drop onto a walkway, a car or a person.
- A downward spiral. More water in the sag means more weight, and more weight makes the sag worse.
A four-step test: can cleaning fix yours?
- Look before you clean. From the ground, sight along each run. Note where it dips, and any gap between the trough and the fascia.
- Clean and flush. Empty the run completely, then run a hose at the high end.
- Look again while it is empty. Does the trough rise back toward a straight line? If it does, weight was the main cause.
- Watch the water. It should travel steadily to the downspout. If it pools at the low spot, the sag is structural and the gutter pitch is wrong, whatever the debris load.
If step three passes but the dip returns within a season, add hangers. If step four fails, plan a repair. Soft or dark fascia at the ladder means the trough must come off, the wood must be replaced and the run must be re-hung. That is repair work, not cleaning work.
What not to do, and when to call
Do not prop a sagging trough with a stick or board. Do not drive extra screws through the front face, which tears the metal and leaks. Do not lean a ladder against a sag, and do not pull the trough up by hand, because it can bend or break at the hanger.
A handy person can re-hang a single-storey run with the right hangers. At second-storey height, or where the fascia is rotten, it is a job for a professional. Eavestrough repair vs replacement helps with the decision. D&D Home Services offers gutter cleaning from $125 for a typical Kitchener-Waterloo home and can quote eavestrough installation when a run is past saving, with every price in writing before work begins.
Key Takeaways
- Cleaning fixes a sag only when wet debris caused it and the metal, hangers and fascia are still sound.
- A run that stays low when empty, a gap at the fascia or soft, dark wood behind the trough means repair, not cleaning.
- Sagging troughs hold water, soak the fascia, overflow beside the foundation and can fall on people below.
- Never prop, screw through the front or lean a ladder on a sagging run.
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