Where the water goes

How many outlets a run needs

Not a fixed spacing. It is set by how much roof drains into the run and how far the water has to travel to leave it, and the second factor is the one people miss.

A gutter is an open channel with almost no fall in it. Water entering a long way from the outlet arrives on top of water already moving, so the surface climbs as it travels. On a run carrying serious volume, the water at the far end reaches the top of the trough and goes over the front edge before it ever gets near the downspout. The gutter is not blocked, it is not the wrong shape, and it still fails.

• 1 Water entering far from the outlet arrives on top of water already moving, so the surface climbs as it travels. At the far end it reaches the front edge and leaves. The trough is clean, the profile is right, and it still spills.
• 2 The outlet is where the water can finally go somewhere, so the surface sits lowest there. That is why the end of a run nearest the downspout looks perfectly fine while the far end is going over the front.
• 3 Split the same run and the water travels half as far before it can leave. The surface never climbs to the front edge. Nothing about the trough itself changed.

Splitting a long elevation with a second outlet halves the travel distance and frequently solves the whole problem for a fraction of what upsizing the trough costs. On a long run, outlet count is the first question, not the last.

Separately, valleys and dormers concentrate a large area of roof into one narrow path. Where a valley lands on a gutter, that is a specific point taking a disproportionate share of the water, and an outlet placed there does more than anything else available to that run.

The two downspout sections

Two rectangular sections are in common residential use, and the step between them is bigger than the names suggest: the larger has roughly double the throat area of the smaller.

That buys two things. Capacity, obviously. And clog resistance, which matters more under an Orlando canopy than most people account for: a wad of wet oak litter that bridges across the narrower outlet and stops it dead will often drop straight through the wider one. On a large roof plane in a summer storm, the downspout is very often the actual bottleneck rather than the trough, so pairing a wide trough with narrow downspouts gives most of the upgrade back.

What happens at the bottom

Three ordinary treatments, in ascending order of how well they work.

• 1 Splash block. Spreads the discharge so it does not cut a hole under the elbow, and lets it go at the base of the wall. Better than bare soil, and that is about the extent of it.
• 2 Above-ground extension. Rigid pipe carrying the discharge out to ground that falls away. Cheap, effective, visible, and easy to reposition later.
• 3 Buried solid line to a pop-up emitter. The pipe runs underground to a fitting that opens under water pressure and closes again, so the discharge point is chosen rather than inherited from the slope.

Splash block. A molded block that spreads the discharge and stops it cutting a hole directly under the elbow. It lets the water go at the base of the wall, which means the entire roof plane's runoff is still going into the soil against the slab. It is better than nothing and that is roughly the extent of its merit.

Above-ground extension. Rigid downspout material carried out to ground that falls away, or a hinged flip-up elbow where mowing is a consideration. Cheap, effective, and visible. For most houses this is the sensible default.

Buried line to a pop-up emitter. Solid smooth-wall pipe running underground from the downspout to a fitting in the lawn that opens under water pressure and closes afterwards. Tidy, keeps the yard usable, and moves the water clear of the house.

Two things decide whether a buried line keeps working. Use solid smooth-wall pipe rather than corrugated flexible pipe, because corrugation catches debris and silt at every ridge. And make sure the emitter can be found and cleared. Old buried lines that have silted up solid are a common find on Orlando houses, and they can be flushed or replaced without touching the gutter above.

Central Florida soil

Sandy soil drains well, which is a genuine advantage: discharge that would pond on clay soaks away here. But it also moves easily. A roof plane's worth of water arriving in a concentrated stream will cut a channel through bedding, undermine paver edging, and strip mulch off a bed in a single storm. On lots that slope toward a lake, which is a lot of Maitland, Windermere and Casselberry, it will also carry that material straight into the water.

The answer is spreading the load: more outlets so each one carries less, discharge onto gravel or turf rather than bare bed, and buried lines where the water needs to travel far enough that a surface extension would be in the way.

The neighbor question

A recurring temptation on tight lots: the ground falls toward the fence, so point the extension that way and the water leaves. It is worth knowing that Florida law does not treat this as automatically your right.

Florida applies the reasonable use rule to surface water, adopted by the Florida Supreme Court in Westland Skating Center, Inc. v. Gus Machado Buick, Inc. in 1989. Under it, a property owner may alter the drainage on their land, but can be liable where the alteration causes unreasonable harm to a neighboring property. Whether a particular case crosses that line depends on necessity, method, and how foreseeable the harm was.

In practice this means directing a downspout so it discharges onto the lot next door is a real exposure rather than merely a bad neighborly move, particularly if it demonstrably causes damage. Keeping the discharge inside your own boundary avoids the question entirely, and on a tight lot that usually means a buried line running to an emitter in your own yard rather than a surface extension pointed at the fence.

Where the downspout itself fails

• Separated elbows. Crimped joints that were never fastened work apart under the weight of water. Refastening and strapping is a small repair.
• Missing straps. A downspout relying on friction at the elbows will pull away from the wall eventually.
• Silted buried lines. Common on older properties, invisible from the surface, and the reason a gutter that used to work suddenly backs up at one outlet.
• Discharge onto hardscape. Water put onto a driveway or path goes somewhere, and in a storm that somewhere is usually the lowest point, which is frequently a garage.