How much do downspouts and downspout extensions cost?

Adding or replacing downspouts costs about $1,099 to $2,000 for a typical job, with a national average of $1,527, according to Fixr (updated January 31, 2025). Per linear foot, Fixr puts installation at $15 to $28; HomeAdvisor, which prices only the material and the swap, gives $5 to $11 per foot (updated June 17, 2026). The extension that carries water away from the house is the cheap part: $2 to $17 from Fixr, and $10 to $50 per downspout from Modernize. Burying the discharge in an underground drain is the expensive part, at $15 to $35 a foot and about $2,800 on average (Modernize, August 12, 2026).

The gap between sources comes from what each one prices. Read an estimate line by line before you compare totals.

What downspouts cost, by source

Fixr also gives sample totals for a professional job: $541 to $2,289 for six 12-foot aluminum downspouts, $454 to $1,765 for six galvanized, and $2,961 to $9,019 for twelve copper. It lists installation per foot by material as $7.52 to $31.79 for aluminum, $6.31 to $24.51 for galvanized steel, $5.79 to $10.53 for PVC and $20.56 to $62.63 for copper. Fixr's handyperson rate is $37 to $68 an hour.

The two disagree because they price different jobs. HomeAdvisor's per-foot ranges are for replacing downspouts; Fixr's cover whole installations, and neither says more about scope, so ask each installer what a figure includes. If your gutters are being replaced, downspouts are usually part of that price, as HomeAdvisor counts them: see how much gutter replacement costs.

Downspouts by material

• Vinyl and PVC cost least per foot in both Fixr's and HomeAdvisor's figures.
• Aluminum sits in the middle on price. Fixr lists a sample of four painted aluminum downspouts at about $768.
• Galvanized steel runs $10 to $11 a foot at HomeAdvisor, about double aluminum there.
• Copper is the top of the range: Fixr's twelve-downspout copper job reaches $9,019.

Match the downspout to the gutter. Our guide to seamless vs sectional gutters covers gutter materials and how long each lasts.

Size and how many you need

Downspouts are sized by how much roof drains into them. Modernize (citing SMACNA capacities) and This Old House (updated April 20, 2026) give the same figures:

The larger rectangular size goes with a 5-inch K-style gutter on a bigger or wetter roof; round downspouts go with half-round gutters. This Old House gives a rule of thumb of one square inch of downspout opening for every 100 square feet of roof, and says a gutter run of 60 feet or longer needs at least two outlets.

Bob Vila (June 10, 2026) gives a simpler count: about one downspout per 30 feet of gutter, one per 20 feet on steeper roofs and one per 40 feet on shallow ones. These are rules of thumb from publishers, not code. A roof with long valleys sends a lot of water to one corner, so ask the installer to show you which part of the roof drains where. If your gutters overflow in heavy rain with the old layout, more or larger downspouts are one of the fixes, and a pro should size them.

Extensions and where the water goes

A downspout that ends beside the foundation pours roof water into the soil there. InterNACHI, the home inspectors' association, says downspouts that discharge next to the foundation are a very common condition that inspectors should report as a defect, and that a device such as an extension or splash block should carry runoff away.

How far is "away" depends on whom you ask:

• At least 3 to 4 feet from the foundation (This Old House).
• 4 to 6 feet, with 8 to 10 feet in heavy clay (Bob Vila).
• At least 6 feet, 10 preferred when space allows, and more on sloped yards, clay soil or with a finished basement (Modernize).
• At least 5 feet where soils are expansive or collapsible, according to the 2021 International Residential Code section R801.3, as InterNACHI cites it. Your local code may differ; check with your building department.

Common types are a hinged or fold-up piece, a flexible or accordion pipe and a rigid pipe. Bob Vila says an extension should slope down at least a quarter inch per foot, and that a splash block throws water only about 2 feet, so it works only where the ground already falls away from the house. For what poor discharge does to a basement, see our guides on overflowing gutters and gutters and foundation damage.

Underground downspout drains

A buried pipe takes the water to a pop-up outlet, an open end or a lower spot in the yard. Modernize prices it as follows (August 12, 2026):

Modernize says PVC lasts 30 to 50 years and corrugated pipe 10 to 20, and that trenches run 6 to 12 inches deep with about 1 inch of drop for every 8 to 10 feet. Poor slope makes water pool in the line. Cost depends on trench length, soil and labor rates, so ask each installer how long the pipe will be and where it ends. A pipe that ends too close to the house or a neighbor's yard only moves the problem.

What to put in the estimate

• The number, size, shape and material of every downspout.
• Where each one discharges, how far from the house, and what carries the water there.
• Whether elbows, brackets, screens and extensions are included.
• Removal of the old downspouts.
• A price per foot for extra pipe, so a change on site has a known cost.

Check the installer as well as the estimate: our guide to questions to ask a gutter installer lists what to ask. Guards on the gutter do not change how many downspouts you need; see what gutter guards cost.

Frequently asked questions

How much does it cost to add a downspout?

Fixr's national range for a professional job is $1,099 to $2,000, but that covers a full set. A single added downspout on a simple wall costs far less than a whole house of them; ask for a per-downspout price in writing.

How far should a downspout extension reach?

Sources range from 3 or 4 feet to 10 feet. Six feet is the middle figure; clay soil, a slope toward the house or a finished basement argue for more. Check your local code.

Are splash blocks enough?

Only on ground that already slopes away. Bob Vila says a splash block carries water about 2 feet, and the slope needs to be about 6 inches over the first 6 feet.

Do I need an underground drain?

Not usually. Above-ground extensions cost a tenth as much. Consider a buried line where space or the yard layout makes an open extension unworkable, and have a pro check the slope and the outlet.

Does a homeowners policy pay for new downspouts?

HomeAdvisor says insurance typically covers sudden storm damage, not wear. Your policy decides. This is general information, not insurance advice.

How we got these numbers

HomeAnvil does not yet publish price data of its own. Each figure comes from the source named beside it, read on October 13, 2026. Prices differ because the sources measure different things, so we show them side by side. The price at the top of the page is Fixr's typical range.

• Fixr, downspout installation cost, updated January 31, 2025: whole-job, per-foot, material and extras figures.
• HomeAdvisor, gutter repair cost, updated June 17, 2026: per-foot replacement and removal costs, insurance.
• HomeAdvisor, gutter replacement cost, updated June 20, 2026: splash block and screen prices.
• Modernize, extending gutter downspouts, updated August 12, 2026: extensions and discharge distance.
• Modernize, underground drainage cost, updated August 12, 2026.
• Modernize, gutter sizes, and gutter repair, both updated August 12, 2026: downspout sizes (SMACNA capacities) and repair cost.
• This Old House, how to size gutters and downspouts, updated April 20, 2026, and about gutter downspouts, undated: sizes, outlets, discharge distance.
• Bob Vila, downspout length and extensions, June 10, 2026.
• InterNACHI, roof drainage (undated; cites the 2021 International Residential Code R801.3), and its roof drainage systems article (read through a search summary) and roof drainage systems, part 2.

Rules on drainage and permits vary, so check with your building department. We will update this page when these sources change.

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