Why Are My Gutters Overflowing in the Rain?

Why are my gutters overflowing?

Most of the time, the water cannot get out. A downspout or the elbow at its bottom is packed with needles, or the gutter is so full of leaves that rain runs over the front edge instead of along it.

Around Sonora, what we pull out is mostly pine needles, oak leaves and cones. Wet needles pack down tight, and the water carries them toward the downspout opening, which is the only way out.

Less often the gutter is clean and still spills. Then the trouble is the gutter itself: a sag, a run with no fall toward its downspout, or one downspout trying to drain too much roof.

Start with the easy cause. A gutter and downspout cleaning empties every run and flushes every downspout. If water still comes over the edge after that, you know the problem is the gutter, not what was in it.

Where is it spilling, and what does that tell you?

Where the water comes over is the best clue you have. Watch from somewhere dry during the next rain and note the spot.

Tell us where it spills when you call or send the form, and we know where to look first.

How can you tell if a downspout is clogged?

Watch the bottom of it in a rain. If the gutter above is full and the downspout gives a trickle or nothing, it is plugged somewhere between the top and the ground.

There are two places to check. One is the opening at the top, where needles wad up over the hole. The other is the bottom, where the pipe turns. NC State Extension puts it simply: "Downspouts and downspout elbows should be clear of debris."

On a dry day you can check the bottom from the ground and pull out what you can reach with a gloved hand. The real test is the one we do on every downspout: a hose down the top until water pours out the bottom.

On a single-story house, with a sturdy ladder on firm ground and someone holding it, you can run that test yourself. On anything taller, we would leave it to a crew.

If your downspout runs into a pipe in the ground and the downspout itself is clear, the clog may be in the buried line. That is drainage work, not gutter work, and we will tell you so and point you to someone who does it.

Why do foothill gutters overflow in the first big storms?

Because the gutters fill all fall, and the heavy rain comes right behind. Ponderosa pines start dropping needles in late September, and UC ANR says, "Fast forward to January and they are still coming down." Oaks around Sonora drop most of their leaves in November and December.

The rain follows the same calendar. NOAA's 1991 to 2020 normals for Sonora give October about 1.6 inches of rain, November about 3.2, December about 5.5 and January about 6.3, the wettest month of the year.

So a gutter that handled an October shower can spill in a December storm, with a whole fall of leaves and needles in it and more than three times the rain.

The roof feeds the gutters too. Needles left on the shingles wash down with every rain, which is why clearing pine needles off the roof goes with a gutter cleaning. For the months that work best under oaks and pines, see our gutter calendar for the foothills.

Can a clean gutter still overflow?

Yes. If the gutter and downspouts are clear and water still comes over the edge, look at the gutter itself.

• A sag. A gutter that has pulled down holds water in the low spot and spills there.
• No fall. A gutter has to slope toward its downspout. PNNL's Building America guide says gutters go on "so they slope" along the eaves. A run that sits flat, or tips the wrong way, holds water.
• Too few downspouts. The same guide notes that "the more closely downspouts are spaced along the gutter, the more water can be conducted away during peak rainstorms." A long run with one outlet can fall behind in a downpour even when it is clean.
• A guard covered in needles. Guards keep most debris out of the gutter, but UC ANR's Fire Network says they "may still require periodic attention." Needles that build up on top can turn rain away from the gutter. More on that in gutter guards for pine needles.

We do not rehang sagging gutters, re-slope them or add downspouts, and we do not reseal seams or fit guards either: that is work for a licensed gutter contractor. When one of those is the cause, we say so on the estimate and tell you to call one. What we do is clear the gutters, including the needles on top of and under any guards, with gutter guard cleaning.

What does overflowing water do to your house?

It drops the roof's water at the foundation, the one place you do not want it. PNNL's guide says "the immense volume of water coming off the roof can quickly saturate the soil surrounding the building," and that runoff has to be carried away "to keep the basement or crawlspace dry." Once moisture gets inside, it "can lead to a variety of problems, including mold and rot."

The board behind the gutter suffers too. A gutter that stays full keeps that board wet, and a soft board lets the gutter pull away, which makes the next overflow worse.

Where the downspout lets out matters as much as the gutter. NC State Extension says "Splash blocks are not recommended as they release water too close to the home." For a pipe run underground, it recommends an outlet at least 10 feet downhill and away from the house. That is their recommendation, and your lot and slope may call for something different.

What should you do while it is raining?

Stay off the ladder and off the roof. Wet rungs and wet shingles are how people get hurt, and no gutter is worth that.

From the ground, this is what helps:

• Note where the water comes over.
• Check the bottom of each downspout for a full stream of water or only a trickle.
• Look along the wall below the spill for water pooling against the house.

Then call us and we will clear it between storms, on a dry day. Tell us where it spilled when you call or send the form. We look at the gutters, the downspouts and the roof above them, and you hear from us what is causing the overflow before anyone starts work.