Doorway or pedestrian route along the wall
- Typical implication
- Gutters usually worth it — drip line across an entrance is a year-round nuisance
Accessory guide
Gutters and Downspouts
On a steel building, gutters are an option rather than a given. This guide covers what they change, when leaving them off is a reasonable decision, and the part most quotes ignore entirely — where the water goes after the downspout.
House buyers assume gutters. Steel building buyers should not: plenty of agricultural and storage buildings are built without them, and the roof simply sheds water off the eave onto the ground below.
Whether that is acceptable depends on what is under the eave, how the site drains, what the doors are, and whether anyone has to walk there. This page is about making that a decision rather than an omission.
Written by Gary Thompson · Steel Building Research EditorSteel Building Research EditorReviewed by Find Steel Buildings Editorial Team
What happens with no gutters at all
Water leaves the eave in a line along the full length of the building and lands wherever the ground is. On a well-drained site with a wide apron and nothing along that wall, that is genuinely fine, and many buildings are built that way deliberately.
It becomes a problem when the drip line lands against the slab edge, splashes back onto the wall panels, erodes a soft verge, freezes across a doorway, or falls where people and vehicles pass. Those are site conditions, not building conditions, which is why nobody can answer the question for you from a catalogue.
What a gutter system actually consists of
The gutter itself is only part of it. There is the eave detail where the gutter attaches, the hangers and straps that hold it, end caps, outlets, downspouts, elbows and the brackets that fix the downspouts to the wall — and then the discharge arrangement at the bottom.
Every one of those is a place a quote can be incomplete. The most common gap is the last one: the downspout ends a foot above the ground and nothing in anyone's scope carries the water away.
- Gutter
- The channel at the eave, supported by hangers and closed with end caps.
- Outlet
- The opening where water leaves the gutter into a downspout.
- Downspout
- The vertical run down the wall, with elbows and wall brackets.
- Discharge
- What happens at the bottom — splash block, extension, or a connection to site drainage.
Where the water actually goes
- 01Roof panel sheds water to the eave
- 02Eave trim closes the low roof edge
- 03Gutter collects along the eave
- 04Outlet and downspout carry it to ground
- 05Discharge — usually site work, and the most common gap in a quote
- 06Without gutters, the drip line lands along the full length of the wall
The eave interface is where it goes wrong
Gutters on a metal building attach at the eave, which is also where the eave trim, the panel edge and any closures live. If the gutter is added by someone other than the building supplier, that junction is being detailed by a second party against a first party's system.
This is a strong argument for specifying gutters with the building rather than afterwards. When they are in the building package, the eave trim, hangers and closures are designed to work together and are supplied in matching material and finish.
Where the water goes is a site question
Collecting water at four downspouts concentrates what used to fall in a line into a handful of points. If those points discharge next to the slab, you have made the drainage situation worse rather than better.
Discharge arrangements — splash blocks, above-ground extensions, buried pipe to a soakaway or to a storm connection — are site work, usually outside the building supplier's scope entirely. Some jurisdictions also regulate where stormwater may be discharged, so this is a question for whoever handles your site work and your local authority rather than an assumption.
When gutters are clearly worth it
Some situations make the decision easy: a doorway people use in bad weather, a walkway or parking against the wall, a wall in a finished or customer-facing area, a neighbouring boundary close to the eave, or any intention to harvest rainwater. Others make it easy the other way: a field building with a wide gravel apron and no foot traffic.
Sizing is not done here
Gutter and downspout sizing depends on the roof area draining to each run and the rainfall intensity used for your location. We publish no sizing figures. That calculation belongs to the building supplier or your design professional using the data for your site.
Reading your own site
Vehicles parked or manoeuvring against the wall
- Typical implication
- Gutters usually worth it
Soft ground or landscaping at the drip line
- Typical implication
- Gutters or a hard apron; unmanaged runoff erodes
Wide hard apron, no foot traffic
- Typical implication
- Often reasonable to omit
Boundary or neighbouring property close to the eave
- Typical implication
- Check local requirements before deciding to omit
Rainwater harvesting intended
- Typical implication
- Gutters are the collection system; specify with the building
These are general planning observations, not requirements. Local drainage rules and your site's conditions govern.
What to confirm on the quote
Which elevations are guttered
- Why it matters
- Partial gutter runs are common and often unstated.
Downspout count and locations
- Why it matters
- Determines where concentrated discharge lands.
Material and finish
- Why it matters
- Should match the panel coating system for appearance and durability.
Hangers, outlets, end caps and elbows
- Why it matters
- Small parts routinely absent from a lump-sum line.
Discharge arrangement
- Why it matters
- Usually site work. Confirm who owns it, in writing.
Sizing basis
- Why it matters
- Ask what roof area and rainfall data the sizing used.
Terms used on this page
- Eave
- The low horizontal edge of the roof, where the gutter attaches.
- Outlet
- The opening in the gutter that feeds a downspout.
- Downspout
- The vertical pipe carrying water from the gutter to ground.
- Splash block
- A simple ground piece that spreads discharge away from the base of the wall.
- Drip line
- The line on the ground where water falls from an unguttered eave.
Confirm these on the quote
- 01Elevations covered. Which walls are guttered and which are not.
- 02Downspout locations. Marked on the drawing, checked against doors and traffic routes.
- 03Finish match. Same coating system as panels and trim.
- 04Discharge owner. Named. This is the most common gap in the whole scope.
- 05Local drainage rules. Checked before assuming discharge to ground is acceptable.
Frequently asked questions
Not inherently. Many are built without them and shed water straight off the eave, which is fine on a well-drained site with a hard apron and no foot traffic along the wall. Gutters become worth it when the drip line crosses a doorway or walkway, splashes the wall, erodes soft ground, or falls close to a boundary. It is a site decision rather than a building one.
Yes, but the eave is where the gutter, the eave trim, the panel edge and the closures all meet, so adding gutters later means a second party detailing into the building manufacturer's system. Specifying them with the building gets you matching material, matching finish and an eave detail designed as one thing.
Sizing depends on the roof area draining to each run and the rainfall intensity used for your location, so we do not publish figures that would be wrong for most readers. Ask your building supplier what roof area and what rainfall data their sizing is based on — that question alone tells you whether a calculation was done or a default was applied.
Away from the building, and somewhere your site can actually take the water. Concentrating a whole eave's runoff into a few points next to the slab is worse than no gutters at all. Discharge arrangements are usually site work outside the building supplier's scope, and some jurisdictions regulate where stormwater may go, so confirm both the responsibility and the local rules.
Usually, and it is worth stating explicitly. Gutters and downspouts run the full length of a building at eye level, so a mismatch is very visible. Ask for them in the same coating system as the panels and trim, not just the same colour name, so the whole envelope ages together and sits under one finish warranty.
Verification and sources
Every material statement on this page maps to a published source, and each record states what that source does not cover. Where something was not verified it is recorded as not verified rather than estimated.
Roof drainage is a designed system · Tier 1
Roof drainage components, including gutters and downspouts, are sized against contributing roof area and design rainfall data rather than by default.
Establishes that sizing is calculation-based. No code figure, rainfall value or sizing method is reproduced.
International Code Council — plumbing and drainage provisionsSheet metal gutter practice · Tier 2
Gutter and downspout construction and attachment are covered by published architectural sheet metal industry standards.
Cited to locate the standard practice. No detail is reproduced or applied.
SMACNA — architectural sheet metalStormwater discharge is regulated · Tier 1
Stormwater discharge from developed sites is subject to regulation, with requirements varying by jurisdiction.
Establishes that rules exist and vary. No requirement is stated or applied to any site.
US EPA — stormwater programNot verified · Tier 4
No gutter size, downspout size, spacing, capacity or rainfall figure is published on this page.
Records a deliberate absence. Sizing belongs to the supplier or design professional using site-specific data.
Find Steel Buildings editorial policyWhere to go next
Next step
Trim and flashing
The gutter attaches into the eave trim detail; the two are specified together.
Also useful
Compare building quotes
Gutter scope and discharge responsibility are quote-stage questions.
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Compare steel building quotes
Gutters are cheap to add with the building and awkward to add afterwards. Decide at quote stage, and make sure someone owns the discharge.
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