Roof Drip Edge Code in Kentucky: The One Roof Rule the State Rewrote

Roof Notes · Kentucky Code

Kentucky amends a lot of the residential code. In the entire roof assemblies chapter it amends exactly one section — the drip edge — and the Kentucky version is broader than the national one. It allows things the base code does not. If a contractor or an inspector is working from a generic IRC summary on Central Kentucky shingle work, they are reading the wrong paragraph.

What does the Kentucky code require for roof drip edge?

A drip edge at eaves and gables of shingle roofs, lapped at least 2 inches, extending at least a quarter inch below the sheathing and 2 inches up the deck, fastened no more than 12 inches on center.

Section R905.2.8.5 of the 2018 Kentucky Residential Code, Third Edition, states it in full:

“A drip edge shall be provided at eaves and gables of shingle roofs. Adjacent pieces of drip edge shall be overlapped a minimum of 2 inches (51 mm). Drip edges shall extend a minimum of 0.25 inch (6.4 mm) below the roof sheathing and extend up the roof deck a minimum of 2 inches (51 mm). Drip edges shall be mechanically fastened to the roof deck at a maximum of 12 inches (305 mm) on center with fasteners as specified in Section R905.2.5. Underlayment shall be installed over the drip edge along eaves and under the drip edge on gables.”

Five measurable requirements and one sequencing rule. The sequencing rule is the one that gets missed on real jobs, so it is worth separating out.

Why does underlayment go over the drip edge at eaves but under it at gables?

Because water moves differently in the two places. At the eave, water runs down to the edge and must get onto the metal. At the gable, wind drives water sideways and the metal has to shed it away from the underlayment.

Get it backwards at the eave and the underlayment ends behind the drip edge, which lets water that reaches the felt run behind the metal and onto the fascia and the deck edge instead of into the gutter. It is a small mistake that produces rotted fascia, a stained soffit and a deck edge that fails years before the shingles do. It is also invisible from the ground once the shingles are on.

This is one of the specific things worth looking for when a roof is only a few years old and the fascia is already soft. The shingles can be fine and the flashing details can still be wrong. The same logic — water has to be given somewhere to go, not just something to hit — is what drives vent leaks as well.

The sentence Kentucky added that the national code does not have

Kentucky’s amendment continues past the standard language to permit alternatives, and this is the part no generic drip edge article covers.

The Kentucky section adds: “Alternate methods to the standard metal drip edge may include site formed coil stock that creates a drip line as intended by the code. Wood, composite, and manufactured trim installed on the fascia shall create a drip line to prevent water from running back under the shingles, which will meet the requirements of the drip edge.”

Read that carefully, because it cuts both ways.

In the homeowner’s favour: site-formed coil stock counts, and so does fascia trim that genuinely creates a drip line. On older Central Kentucky houses with existing wood or manufactured fascia trim, Kentucky’s code does not force that detail to be torn off and replaced with factory drip edge to be compliant. That is a real cost difference on a re-roof.

Against a sloppy job: the permission is conditional on function, not on appearance. The language is “shall create a drip line to prevent water from running back under the shingles.” Trim that does not create that drip line is not an alternate method — it is just trim. “There’s fascia board there” is not the standard the section sets.

How long has this been the rule?

Unchanged across at least two editions. We compared the Second Edition published May 2020 against the Third Edition published August 2024 and the drip edge section is word for word identical.

Both documents are published by the Kentucky Department of Housing, Buildings and Construction, and we read both PDFs on 26 September 2026 and compared the section text directly. Nothing in R905.2.8.5 moved between them.

That matters for two reasons. If your roof was installed any time in the last several years, this is the standard it should have been built to — the rule did not change underneath it. And if someone tells you the drip edge requirement is new, or that the alternate-methods language was recently added, the published documents say otherwise. Which edition applies to a specific permit is still a question for the authority having jurisdiction, and Central Kentucky jurisdictions do not all enforce identically — that is the same wrinkle behind which rulebook applies to your roof.

What to actually check on your own roof

From the ground with binoculars you can see two of the five requirements: whether there is a metal edge or a functioning drip line at the eaves and rakes at all, and whether the pieces visibly lap rather than butt together. The quarter-inch projection below the sheathing, the 2-inch return up the deck and the 12-inch fastener spacing are not visible after installation. Neither is the underlayment sequence.

Which is why those are the items to put in writing before the work happens rather than argue about after. On a re-roof proposal, the sequencing line is the one to ask about by name: underlayment over the drip edge at the eaves, under it at the gables. A roofer who builds to the Kentucky section will answer that in one sentence. It is a fair question and a short one, and asking it before the tear-off costs nothing — the permit conversation is the natural place for it.

Is drip edge required on all Kentucky roofs?

Section R905.2.8.5 is written for shingle roofs and requires a drip edge at eaves and gables of shingle roofs. Other roof covering types are governed by their own sections of Chapter 9, and commercial and multi-family work may fall under the Kentucky Building Code rather than the Residential Code. Which code and which section apply to a specific building is a question for the local building official.

Can existing fascia trim satisfy the drip edge requirement in Kentucky?

The Kentucky amendment says wood, composite and manufactured trim installed on the fascia “shall create a drip line to prevent water from running back under the shingles, which will meet the requirements of the drip edge.” The condition is that it actually creates that drip line. Whether a particular existing detail does so on a particular house is an inspection judgement, not something that can be decided from a photograph.

Does a missing drip edge mean the roof has to come off?

Not necessarily — drip edge can sometimes be added at the eaves and rakes without a full tear-off, depending on the shingle course at the edge, the condition of the deck edge, and how the underlayment was run. It is a job-specific call. The reason to look at it at all is that the failure it causes shows up in the fascia and deck edge rather than as a ceiling leak, so it tends to be found late.

One observation from doing this work in Central Kentucky. Drip edge is the cheapest component on a roof and the one most often treated as optional trim rather than as a code-required water management detail. Kentucky is unusual in having gone out of its way to write a local amendment about it — out of an entire chapter on roof assemblies, this is the section the state chose to rewrite. That is a signal about what the state has seen fail.

This is general code information, not a code ruling and not an inspection of your roof. Code interpretation and enforcement belong to the building official with jurisdiction over your property.

All quoted code language above is from Section R905.2.8.5 of the 2018 Kentucky Residential Code, Third Edition (August 2024), published by the Kentucky Department of Housing, Buildings and Construction. Third Edition and Second Edition (May 2020) PDFs both read and compared 26 September 2026. Last updated 26 September 2026.

By Marcos Gil, REALTOR® — Keller Williams Commonwealth · KY Real Estate License No. 296259 · Call or text (859) 310-1209.