Best Downspout Extensions
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Downspout extensions are one of the cheapest, highest-impact upgrades available for a home with any foundation moisture concerns, and the right option depends mostly on your yard’s slope and how much you want the extension out of sight.
How we picked these
We haven’t lab-tested these — picks reflect published specs and verified retailer availability. The right option depends mostly on your yard’s slope, your soil type, and how much you care about the extension being visible day to day.
Flexible extensions
A flexible downspout extension is a corrugated, accordion-style tube that stretches out when needed and compresses back down out of the way for mowing. It’s the cheapest option on this list and the easiest to install, with no tools required beyond attaching it to the downspout outlet, which makes it the reasonable first thing to try before spending more on a permanent solution.
Flexible downspout extension
Quick, low-cost fix on most lots
| Length | Extends to ~4–8 ft |
|---|
Pros
- Cheap and easy to install
- Rolls back when not needed
Cons
- Can look untidy
- Less durable than rigid options
Rigid roll-out extensions
Roll-out extensions use a spring-loaded reel that unrolls automatically under the weight of flowing water and retracts once the flow stops. It’s a step up in tidiness from a flexible tube that’s left permanently stretched out across the lawn. They cost a bit more and have moving parts that can eventually wear out, but for a highly visible spot near a front walkway, the cleaner look is often worth it.
Rigid roll-out extension
Visible spots near walkways
| Action | Unrolls under water flow, retracts after |
|---|
Pros
- Tidy when dry
- Fully automatic
Cons
- Moving parts eventually wear
- Costs more than a flexible tube
Underground drainage kits
For homes with persistent foundation moisture that surface extensions alone haven’t solved, an underground drainage kit routes the downspout through buried pipe to a discharge point well away from the house, sometimes daylighting at a lower point in the yard, sometimes into a dry well. It requires trenching and real installation effort, but it’s the only option here that gets the downspout extension entirely out of sight and out of the way.
Underground downspout drainage kit
Persistent foundation moisture, tidy appearance
| Install | Requires trenching |
|---|
Pros
- Routes water well away from the house
- Out of sight, no tripping hazard
Cons
- More expensive and labor-intensive
- Can clog if not maintained
Splash blocks and rain barrel diverters
A splash block is the simplest option of all: a shaped concrete or plastic block that sits under the downspout outlet and directs water a short distance away while preventing soil erosion right at the discharge point. It’s not a substitute for real extension on a lot with drainage problems, but it’s a reasonable minimum for a downspout that already discharges onto well-sloped ground. A rain barrel diverter serves a different purpose entirely: it routes water into a collection barrel for garden use rather than simply moving it away, which is worth considering for anyone who wants to get some use out of the runoff rather than just disposing of it.
Splash block
Well-sloped ground, stopping erosion at the outlet
| Type | Concrete or plastic |
|---|
Pros
- Cheapest option on this page
- Zero maintenance
Cons
- Moves water only a short distance
- Not a fix for real drainage problems
Rain barrel diverter kit
Putting runoff to use in the garden
| Install | Cuts into the downspout |
|---|
Pros
- Collects water instead of dumping it
- Overflow routes back to the downspout
Cons
- Barrel needs draining before hard freezes
- Not a drainage solution by itself
Cost comparison
| Type | Typical price |
|---|---|
| Splash block | $5–$15 |
| Flexible extension | $10–$20 |
| Rigid roll-out extension | $20–$40 |
| Underground drainage kit | $100–$400, DIY |
| Ranges reflect published pricing and marketplace averages, not a quote. See our cost methodology. | |
Starting cheap and working up
Given how inexpensive a flexible extension is, it’s a reasonable first move even before you’re sure it’ll fully solve a moisture problem. If it helps but doesn’t fully fix things, that’s useful diagnostic information before committing to trenching for an underground kit.
Rather have a pro install it? Compare quotes from local pros.
Frequently asked questions
How far should downspouts extend from the house?
See our full guide on downspout extension distance. As a starting point, most homes benefit from at least 4-6 feet of extension, more on flat or clay-heavy lots.
Do downspout extensions need to be permanent?
No. Flexible and roll-out extensions are designed to be moved or retracted for mowing, then repositioned afterward. Underground kits are the only genuinely permanent option on this list.