Quick Summary

Many slate roofs on New Orleans historic homes fail at the fasteners rather than the stone. The nails rust through while the slate is still sound, and the National Park Service says plainly that plain steel and galvanized nails usually rust out long before the slate itself begins to deteriorate. That distinction matters, because a roof losing slates to failed fasteners can often be repaired rather than replaced. Big Easy Roofing works on slate across Orleans, Jefferson and St. Tammany parishes, where exterior work visible from the street in a historic district needs a Certificate of Appropriateness first, from either the Historic District Landmarks Commission or the Vieux Carre Commission.

Last Updated: September 2026

On this page

• Why Do Slate Roofs Fail on New Orleans Historic Homes?
• How Long Should a Slate Roof Actually Last?
• Can You Walk on a Slate Roof Without Damaging It?
• Should a Failing Slate Roof Be Repaired or Replaced?
• Do You Need Historic District Approval to Repair a Slate Roof in New Orleans?
• What Drives the Cost of Slate Roof Repair?
• Frequently Asked Questions

A slate roof that is shedding pieces onto the garden looks like a roof at the end of its life. Usually it is not. The failure point on most historic slate is the fastener and the flashing, both of which have a far shorter service life than the stone, and telling those apart is the difference between a repair and a five figure replacement.

Why Do Slate Roofs Fail on New Orleans Historic Homes?

The fasteners commonly go first. National Park Service guidance states that non-ferrous slater’s nails, such as copper or stainless steel, should always be used, since plain steel and galvanized nails will usually rust out long before the slate itself begins to deteriorate. A roof nailed with plain steel will drop sound slates decades before the stone is spent.

Preservation Brief 29, written by Jeffrey S. Levine for the National Park Service, sets out four things that decide how long a slate roof survives: the physical and mineralogical properties of the slate, the way it was fabricated, the installation technique, and regular timely maintenance. Only the first is about the stone. The other three are workmanship, which is why two roofs of identical slate laid in the same decade age so differently.

Two installation faults show up repeatedly on older New Orleans roofs. Nail heads driven tight and left exposed accelerate deterioration by providing a point for water entry, because the slate should hang freely on the nail shank rather than be clamped against the deck. And where joints are improperly broken, meaning slates lap the joints in the course below by less than three inches, water passes between the joints, through the nail holes and into the felt beneath.

How Long Should a Slate Roof Actually Last?

Sixty to one hundred and twenty five years, and often longer, depending on the slate. That range comes from the National Park Service, which also breaks it down by quarry: Vermont and New York slates last about 125 years, Buckingham Virginia slates 175 years or more, and Pennsylvania Soft-Vein slates in excess of 60 years.

The two hundred year claim people repeat about slate is not a myth, but it is specific. Peach Bottom slate had a life span of at least 200 years and Pennsylvania Hard-Vein roughly 100, and neither is quarried any more. So the honest answer to how long a given roof has left depends on identifying what is actually on it, which means identifying the slate before pricing any work.

What failing stone looks like is distinctive and worth knowing. Paper thin laminations flake off the surface, and the slate becomes soft and spongy as the inner layers delaminate. That is genuine end of life. Sound slates lying in the garden with rust stains at the nail hole are not.

Can You Walk on a Slate Roof Without Damaging It?

Not without risking damage. Slate cracks under concentrated weight, and the National Park Service advice is blunt: as part of regular maintenance, an attempt should be made to keep foot traffic off the roof. Every unnecessary trip across a slate roof creates the broken units someone later pays to replace.

The steps below are professional access technique, written for roofers and preservation trades rather than homeowners. A fall from a pitched slate roof is a serious injury risk, so this is work to hire out.

• Hook ladders over the ridge and walk on the ladders, so weight is distributed rather than concentrated on individual slates.
• Wear soft soled shoes if slates must be stepped on directly.
• Step on the lower middle of the exposed portion of the slate, which is the part with support beneath it.
• Keep chimney sweeps, painters and satellite installers off the roof unless they know these rules, since they cause a large share of avoidable breakage.

Should a Failing Slate Roof Be Repaired or Replaced?

Repair, wherever the stone is still sound. The National Park Service is direct on historic buildings: because the pattern, detailing and craftsmanship of slate roofs are important design elements, they should be repaired rather than replaced whenever possible. On a contributing building in a historic district that also shapes what will be approved.

The practical test is what failed. Where deteriorated nails or flashings caused the roof to fail, salvage of at least some slates should be possible for use in repairs, so a slate by slate repair keeps the original roof. Where the slate itself is delaminating across whole slopes, replacement is the honest answer. A documented condition survey settles which, and the same record supports a historic district application.

Matching matters more than most homeowners expect. Size, shape, color, texture, exposure and coursing are the characteristics that should be documented and matched when repairing a historic slate roof, and mottled gray Vermont slate is the closest available match for Pennsylvania ribbon slate. Getting that wrong leaves a patch visible from the street for as long as the roof stands, which is precisely what a historic district review exists to prevent. The underlying causes of premature slate failure are worth understanding before commissioning any of it.

Do You Need Historic District Approval to Repair a Slate Roof in New Orleans?

Usually yes, and since 2025 there are two separate approvals rather than one. Ordinance 30,235 MCS requires a residential re-roofing permit for any roof replacement affecting 50 percent or more, and a Certificate of Appropriateness is required separately for exterior work visible from the street in a historic district.

The city publishes the shape of the process, and it is less painful than its name suggests.

1. Work out which commission reviews the property. The Vieux Carre Commission covers the French Quarter. The Historic District Landmarks Commission covers the other local historic districts, including the Garden District, Marigny, Bywater, Treme and the Irish Channel.
2. Confirm the property sits in a local historic district or is an individually designated landmark, using the city’s district maps.
3. Apply through the One Stop Shop, or send the printed form to the reviewing commission’s staff address.
4. Allow three to five days, which the city gives as the normal waiting time for Certificate of Appropriateness applications that staff can approve without a full commission hearing.
5. Budget the re-roofing permit at a sixty dollar base fee, plus thirty dollars where the property sits in an HDLC or Vieux Carre Commission district, and expect the historic review to add time on top of the city’s usual two to four day turnaround.

A like for like slate repair is the path of least resistance through either commission, because it changes nothing a reviewer has to weigh. It can also fall under the fifty percent threshold and stay outside the re-roofing permit altogether, which a full replacement never does.

What Drives the Cost of Slate Roof Repair?

Four things move the number more than square footage does: whether the slate can be salvaged, whether flashings and fasteners need renewing across the whole roof, how difficult access is on a steep slope, and whether matching slate must be sourced. A targeted repair and a full re-slate are different orders of cost.

Slate is quoted per roof after inspection rather than at a square foot rate, because the salvage question alone can move the total by a wide margin and no honest figure survives being guessed from the curb. Two cost items are predictable, though. Flashing renewal is often the real scope, since copper and the joints it protects fail on their own timetable, and the same water entry that damages flashing details on New Orleans roofs is what rots the felt under slate. The second is the permit cost above, which is a flat figure rather than an estimate.

One economic point argues for acting early. A slate roof losing units to failed nails sheds more of them each season, and every slate that reaches the ground is one that has to be matched rather than reused. Owners tracking how roof age affects Louisiana homeowners insurance will recognize the same logic, since documented condition beats a claim argued after the fact.

Frequently Asked Questions

Can a slate roof really last 200 years?

Peach Bottom slate had a recorded life span of at least 200 years according to the National Park Service, but it is no longer quarried. Slates available today are more realistically in the 60 to 175 year band depending on their origin.

Does slate break easily?

Slate is durable against weather but brittle under point loads, so it resists a century of rain and cracks under a workman’s boot. Falling limbs, ice in gutters and valleys, and the weight of someone walking on the roof are all listed causes of individual slates breaking.

What should never be used on a slate roof?

Plain steel and galvanized nails are the main one, because they rust out long before the slate does and cause the failure they were meant to prevent. Roofing cement smeared over slipped slates is a close second, since it traps water and complicates a proper repair later.

How do I know whether my slate is failing or just the nails?

Slate at the end of its life flakes into paper thin laminations and feels soft or spongy. Slates that come down whole, especially with rust staining around the nail hole, point at fastener failure instead.

Is a slate roof worth keeping on a New Orleans home?

On a contributing building in a historic district it usually is, both because the roof is a design element the Historic District Landmarks Commission reviews and because sound slate has decades left once the fasteners and flashings are renewed. Big Easy Roofing assesses that on site across New Orleans, Metairie and the surrounding parishes.

What can a roofer do about an insurance claim on a slate roof?

Establish the physical cause, photograph the condition and write a good faith itemized estimate. Louisiana law does not allow a contractor to interpret policy coverage or adjust a claim, so coverage questions go to your insurer or a licensed public adjuster. Worth knowing: a public adjuster may not carry out the roofing work on a claim they have processed.

How long does historic district approval take?

The City of New Orleans gives three to five days as the normal waiting time for applications that staff can approve, with more complex cases going to the commission itself. Whether that is the Historic District Landmarks Commission or the Vieux Carre Commission depends on which district the property sits in.

Ready to find out whether your slate needs repair or replacement? Call Big Easy Roofing at 504-800-8196 for a documented slate assessment that separates failed fasteners from failed stone. The team works on slate, tile, metal and shingle roofs across New Orleans, Metairie, Kenner, Covington, Mandeville and Slidell, and the written condition record supports both a historic district application and any insurance claim that follows. Homeowners weighing materials will find the background on how slate roofing is made and graded useful first, and the full range handled by this New Orleans roofing contractor covers what comes next if the slate cannot be saved.

About the author: prepared by the roofing team at Big Easy Roofing, a licensed Louisiana contractor that inspects, repairs and replaces slate, cedar shake, tile, metal and shingle roofs throughout Orleans, Jefferson, St. Tammany and Tangipahoa parishes, and documents storm damage for property owners and their insurers.