Does every house need gutters? What the code and building guidance say

Updated November 10, 2026 · KeystoneProGuide editorial team

Does the building code require gutters?

Not on every house. Pennsylvania's Uniform Construction Code adopts the 2021 International Residential Code. That code's roof drainage section, R801.3, requires a controlled method of collecting roof water and discharging it at least 5 feet from foundation walls, or to an approved drainage system, only in areas where expansive or collapsible soils are known to exist. Elsewhere, the code does not demand gutters.

Two other sections bear on roof water without requiring gutters. Section R401.3 requires lots to be graded so surface water drains away from the foundation, with the ground falling at least 6 inches within the first 10 feet. Section R903.4 says that unless a roof is sloped to drain over its edges, roof drains must be installed at each low point, which matters for flat or low-slope roofs.

Does that mean gutters are optional?

Under the state code read for this guide, outside expansive-soil areas, yes, though your municipality may have rules of its own. In practice, the federal guidance treats them as the normal answer. The Department of Energy's Building America Solution Center says gutters or other drainage systems are needed in all but the driest climates of the United States. It explains why: a few inches of rain on a roof can produce several thousand gallons of runoff, and if that is not carried away from the house it can saturate the soil and wick through the foundation, leading to moisture problems including mold and rot.

The U.S. Environmental Protection Agency (EPA) makes the same point from the mold side, listing "landscaping, gutters and down spouts that direct water into or under a building" among common moisture problems, and saying gutters should carry rainwater at least 5 feet from the foundation.

The phrase that matters is "or other drainage systems". Gutters are one way to keep roof water away from a foundation, not the only one.

When can a house go without gutters?

Building America names the cases. It says ENERGY STAR does not require gutters for homes with a slab-on-grade foundation or homes in a dry climate. It also describes an alternative for builders: instead of gutters, a grade-level rock bed around the house, over a waterproof liner, with a drain pipe that carries the water at least 5 feet from the foundation, or to a drywell or other approved point.

For homes without gutters, it says to protect the house from splashing water in one of three ways:

Foundation walls that rise at least 16 inches above the finished ground.
Roof overhangs that put the drip line 16 inches out from the foundation, with siding kept at least 8 inches above the ground.
Cladding that tolerates regular wetting, over a well-sealed drainage layer reaching at least 16 inches above the ground.

Building America also says that in cold and very cold climates, where snow builds up on roofs and gutters freeze, gutters should be avoided in favor of grade-level drainage. The pages read for this guide do not say whether southeastern Pennsylvania counts as cold in that sense, so that advice is noted here, not applied.

Which local houses are the obvious cases?

Slab houses. Levittown, in lower Bucks County, was built between 1952 and 1958 as slightly more than 17,300 houses on concrete slabs, according to the Encyclopedia of Greater Philadelphia. Under the ENERGY STAR rule Building America describes, a house on a slab-on-grade foundation is one where gutters are not required, so long as the walls are protected from splash. That does not mean a slab house should have its gutters taken off; it means the gutter is one option among several.

A house with a basement or crawlspace is the opposite case. Building America says roof runoff must be channeled away from the foundation to keep a basement or crawlspace dry.

What does Philadelphia require?

More than the state. Philadelphia's property maintenance code says roof drainage must be adequate to prevent dampness or deterioration in the walls or interior, that roof drains, gutters and downspouts shall be maintained in good repair and free from obstructions, and that roof water must not be discharged in a way that creates a nuisance. Where a Philadelphia house has gutters, keeping them working is a code duty. Where it has none, the roof drainage still has to meet the adequacy test.

What if your house has no gutters now?

Look at what is doing their job. Walk round the house in a heavy rain:

Is water pooling at the foundation? The EPA says that can lead to indoor moisture problems.
Does the ground slope away from the walls, as the code requires of new lots?
Is siding or the bottom of the wall being splashed, or soil washed out, under the roof edge?
Is the basement or crawlspace damp after rain?

If the answers are reassuring, the house may be one of those the guidance says can do without. If not, the choice is between adding gutters and building one of the alternatives Building America describes. HomeGuide puts new gutters at $12 to $25 per linear foot installed. Choosing new gutters covers sizes and downspouts, and can clogged gutters cause a wet basement covers drainage. Local businesses are on the gutter cleaning directory page.

Sources

2021 International Residential Code, Chapter 8: Roof-Ceiling Construction, International Code Council
2021 International Residential Code, Chapter 4: Foundations, International Code Council
2021 International Residential Code, Chapter 9: Roof Assemblies, International Code Council
34 Pa. Code 403.21. Uniform Construction Code., Commonwealth of Pennsylvania (Pennsylvania Code)
Gutters and Downspouts, U.S. Department of Energy, Building America Solution Center
Text Version of the Mold House Tour, U.S. Environmental Protection Agency
Mold Course Chapter 2, U.S. Environmental Protection Agency
Section PM-304 Exterior Structure (Philadelphia Property Maintenance Code), City of Philadelphia (The Philadelphia Code)
Levittowns (Pennsylvania and New Jersey), Encyclopedia of Greater Philadelphia
How Much Does Gutter Installation Cost? (2026), HomeGuide