What happens if you never clean your gutters? The order things fail in.

Short answer: nothing dramatic for the first year, and then a slow chain of damage that ends at your foundation. A blocked eavestrough rarely fails in one go. It fails in a predictable order, and each step costs more than the one before it. The cleaning itself is $150 to $300 for most homes. Almost everything on the list below costs more than that.

The photo at the top is the start of the chain. That is a metal roof where a dormer meets the main slope, and the corner has caught a season of pine needles and oak leaves. Corners like that feed straight down into the eavestrough below, a handful at a time, every time it rains.

First: the water goes over the front, not down the spout

Your eavestroughs move more water than most people picture. A 25 mm rainstorm on a 100 square metre roof, which is a modest Barrie bungalow, sends about 2,500 litres toward the troughs. That water is supposed to leave through two or three downspouts.

Once the outlet at the top of a downspout packs with needles and grit, it stops. The trough fills, and the water spills over the front edge in a sheet. You will usually notice this one yourself, because a working eavestrough is quiet in a storm and an overflowing one sounds like a tap left on.

On its own, a season of overflow does not cost much. The problem is where all that water lands.

Second: the water lands against the house

An eavestrough exists to carry roof water a metre or two away from your walls. When it overflows, the water drops straight down the face of the wall instead, in a line along the drip edge.

Over a year or two that line digs a trench in the garden bed, washes the mulch away, and splashes mud up the bottom of the siding. On a newer house in Painswick or Holly, that is mostly a cosmetic job. On an older house in Allandale or the north ward of Orillia, where the foundation is block or poured decades ago with no modern membrane, it is the beginning of the expensive part.

Third: the fascia board starts to rot

Behind most eavestroughs is a fascia board, and on a lot of older homes it is still the original wood under a thin aluminium wrap. When a trough sits full, water wicks over the back edge and soaks that board. Dark streaks running down the fascia are the sign it is happening.

Wood that stays wet rots, and rotten fascia cannot hold a screw. That matters because the fascia is what the eavestrough hangs from. It is the stage to worry about most on older streets like downtown Midland and the blocks around Little Lake, where a lot of the houses are older than the aluminium covering them. Replacing fascia is carpentry, not cleaning, and it is priced like carpentry.

Fourth: the trough pulls away from the house

Dry leaves weigh almost nothing. A trough packed with wet, broken-down debris is heavy, and in winter that debris holds water that freezes solid. The hangers along the trough are spaced roughly every 60 to 90 cm and were never meant to carry a full channel of ice.

So the trough sags. Then it tilts outward, which means even the water that should drain now pools at the low spot. Then, often in a March thaw, a section lets go from the fascia altogether. Up on the higher ground around Craighurst and Horseshoe Valley, where the snow sits longer and the freeze-thaw swings are bigger, the load is worse. By then the fix is a re-hang or a new section, not a clean.

The ice side of this, including how ice dams form, is covered in our post on fall timing. The short version is that a full trough going into winter is the single biggest cause of the damage in this section.

Fifth: the water finds the basement

This is the one that turns a $200 job into a five-figure one.

Water dumped against a wall all spring and fall saturates the soil right next to the foundation. Freeze-thaw cycles in that wet soil push against the wall every winter. Eventually the water finds a crack, a tie hole or a window well, and you get a damp corner in the basement, then a stain, then a smell.

Low lakeside lots make it worse, along the Innisfil shore and around Kempenfelt Bay, because the ground is already wet before the roof adds to it. So do walkout basements, where the lowest wall is half below grade on the side the water runs toward. Foundation repair and interior waterproofing are priced in the thousands, and almost none of it is needed if the roof water leaves through the downspouts the way it was designed to.

The things nobody mentions

A few side effects that do not fit the chain but come with it:

• Seedlings. Give a trough enough years and the debris turns into soil, and maple keys will happily sprout in it. Roots get into seams and open them up.
• Mosquitoes. A blocked trough is a long, shallow, sheltered pool of standing water, right outside your bedroom windows. It is ideal for them.
• Stained siding and windows. Overflow carries tannins from rotting leaves down the wall. On white vinyl it leaves brown tiger stripes that do not rinse off with a hose.
• Pests in the soffit. Wet, soft fascia is an easy way in for squirrels and carpenter ants, and both like a dry attic once they are past the edge.

Can you get away with never cleaning them?

Some houses can go longer than others. A newer home in an open subdivision with no trees within throwing distance of the roof might manage once a year, in late fall, and get away with it.

But "never" does not work anywhere in this county. Even a house with no trees collects shingle grit, which settles in the bottom of the trough as a sludge and blocks the outlet just as well as leaves do. Under pines, around Horseshoe Valley and Midhurst, the needles mat into a felt that no rainstorm will flush. Gutter guards slow all of this down, but they do not stop it, which we went into in the guards post.

For most homes here, twice a year is right: late spring and late fall.

How to tell from the ground how far along yours are

You do not need a ladder to check. Walk around the house in daylight and look for these, in rough order of how far the chain has gone:

1. Water spilling over the front edge in the next real rain. Stage one.
2. A trench or bare strip in the garden bed under the eaves. Stage two.
3. Dark streaks down the fascia under the trough. Stage three.
4. A trough line that is not straight when you sight along it from one corner. Stage four.
5. A damp corner or musty smell in the basement on the same side of the house. Stage five, and the one to deal with first.

If you see the first two, a cleaning probably resets the clock. If you see the third or fourth, book the cleaning and ask for photos of the fascia and hangers, because the person on the ladder is the only one who will see the top of that board this year.

What it costs to stop it

We charge $150 to $200 for a single-storey, $200 to $300 for a two-storey, and $300 to $500 for large or complicated rooflines. That is hand-cleared troughs, every downspout flushed until it runs free, debris bagged and taken away, and photos of anything that is starting to go. We are based in Horseshoe Valley, carry $2 million liability and WSIB, and there is no travel charge anywhere in Simcoe County. The price guide explains what moves the number.

You can see the service on the gutter cleaning page, go straight to your town, Barrie, Orillia, Innisfil, Oro-Medonte, Collingwood or Midland, or get a number in a minute from the instant quote.