On a slate or tile roof, the roofing itself is rarely the first thing to give out. The metal is. Valleys, chimney flashings, wall flashings and gutters carry the most water on the roof, and when they’re made of short-lived metal they can fail decades before the slate or tile above them does. That’s why so many fine homes in Colleyville and the towns around it use copper for those details.
I’m Blake Snow. I’ve been roofing for 30 years, I’m the third generation in a family roofing business that goes back 75 years, and I’ve installed tile, slate, copper, standing seam and just about every other roof system there is. Here’s how I explain copper work on slate and tile roofs to homeowners in Colleyville, Southlake and Westlake.
Where copper goes on a slate or tile roof
When people picture a copper roof, they think of a copper bay window or a turret. On a slate or tile home, most of the copper is in places you barely notice:
- Valleys, where two roof slopes meet and channel water from both
- Chimney flashings, including the step and counter flashing and the cricket on the uphill side
- Wall and dormer flashings, where a roof slope runs into siding, stone or stucco
- Pipe and vent flashings through the field of the roof
- Drip edges and eave metal
- Gutters and downspouts, including built-in gutters on some older or custom homes
Each of those is a place where water piles up or changes direction. The slate or tile sheds rain across the open field of the roof, but the metal handles the hard spots.
Why copper fits slate and tile
The rule I go by is simple: the flashing should last as long as the roof. Natural slate and good clay tile are built for the long haul. Putting thin painted steel or aluminum valleys under them means you’ll be lifting that slate or tile to replace the metal long before the roof itself is done, and every lift risks breaking pieces that can be hard to match.
Copper solves that. It’s long-lived, it bends and solders cleanly into the odd shapes a complex roof needs, and it doesn’t need painting. Preservation and slate industry guides both point to copper as one of the best flashing metals for slate.
Copper weight: the number that matters
Copper sheet is sold by weight per square foot, in ounces. Slate and copper industry guides treat 16-ounce copper as the minimum for flashings and recommend 20-ounce copper for valleys and other spots that carry a lot of water or would be hard to get back to later, such as built-in gutters.
Thicker copper matters because water running off slate and tile carries grit, and over years that grit wears the copper thin, especially right where water drips off the roof onto the metal. Heavier copper in the high-wear spots buys time. Some roofers also add a sacrificial copper strip where the flow is heaviest, so the strip wears instead of the valley.
If a quote just says “copper valleys,” ask what weight. It should be written down.
Open valleys vs. closed valleys
There are two common ways to build a copper valley:
Open valleys are long sheets of copper fastened along the valley, with the slate or tile cut back so a strip of copper shows down the middle. They drain well, they’re easier to inspect and clean, and on a tile roof they’re the usual choice, since tile doesn’t lie flat enough to weave.
Closed valleys on slate use copper pieces tucked under each course, so the slates meet at the valley line and you see very little metal. They look clean, but they take a slate crew that knows the method, and both roof slopes have to match for the courses to line up.
Neither one is “better” on every roof. The right call depends on your roof’s pitch, the look you want, and how much water that valley carries.
Don’t mix metals
This is the mistake I see most often on high-end homes, and it’s easy to avoid. When copper touches aluminum or galvanized steel and gets wet, the other metal corrodes faster. Rain running off copper can also eat at aluminum gutters or steel below it.
So a copper valley that empties into an aluminum gutter, or copper flashing held down with the wrong nails, is a problem waiting to happen. The fix is to keep the whole water path in compatible metals:
- Copper flashings with copper or stainless fasteners
- Copper valleys draining into copper gutters, or a properly isolated joint where they meet something else
- Copper or stainless slate hooks for slate repairs
If your home already has a mix of metals, that isn’t an emergency. It’s something to check during an inspection and plan around when work is done.
What copper looks like as it ages
New copper is bright, almost pink. Within months it starts to darken to a brown, then a deeper brown. The green patina people picture takes many years on a sloped roof, and copper in drier climates often stays a deep brown for a long time. All of those stages are natural, and the patina is a protective layer. Some homeowners love the bright look at first, others want it to weather fast, and some prefer lead-coated copper, which weathers to a soft gray. Ask about that before the metal is ordered.
One more detail: water sitting where slate or tile butts meet the copper can pit the metal along that line over time. Good installers raise the edge of the slate or tile slightly off the copper, or add a replaceable strip, so water doesn’t hang there.
Copper on tile vs. copper on slate
The ideas are the same, but the details differ.
On a slate roof, flashings are often woven into the courses, and repairs mean removing slates with a slate ripper and setting them back with hooks or copper bibs instead of face nails and tar. Our slate roof repair page covers that work.
On a clay or concrete tile roof, the tile sits higher off the deck, valleys are usually open, and wall and chimney flashings have to be shaped to the tile profile. On tile, the flashing and the underlayment work together, so when the underlayment is worn out it often makes sense to replace the flashings at the same time. That’s the lift-and-relay approach I wrote about in this Westlake tile post.
Repair, re-flash or full copper upgrade?
Worn copper often shows itself as a yellow-orange tint where the metal has gotten thin, pinholes, or small pits along the water line. Here’s how I sort the options:
- Spot repair: one worn section of valley or one leaking chimney flashing on an otherwise sound roof. We remove the slate or tile next to it, replace the copper, and reset the roofing. Patching the copper is only a stopgap, and sealant smeared onto slate or tile is never the fix.
- Re-flash during other work: if the underlayment is being replaced or the roof is being relaid, that’s the moment to replace every flashing, since the roofing is already off.
- Full copper upgrade: on a home with painted steel or aluminum details under slate or tile, switching valleys, flashings and gutters to copper when the roof is opened up gives the metal the same lifespan as the roof.
Every inspection comes with a free digital photo report, so you can see the condition of the valleys and flashings for yourself.
Hail and copper in Colleyville
Copper is a soft metal. Large hail can dent copper valleys, gutters and downspouts, and those dents can help show hail size on an inspection. NOAA lists 1.5-inch hail at Colleyville on May 27, 2024, so it’s worth knowing what’s up there. We document dented copper along with any cracked slate or tile, piece by piece, so you and your adjuster can see it. Our storm damage page explains how inspections and claims work.
In Texas you generally have one year from the date of loss to file a claim, but check your own policy, since some differ. Get the roof inspected first, and file only if the inspection finds real damage.
Colleyville permits
The City of Colleyville requires a permit on all re-roof projects, and contractors have to be registered with the city. If copper work is part of a larger re-roof or relay, it’s covered in that process. Check with your HOA or architectural committee too if the look of the roof or gutters will change. In Grapevine, Keller or Trophy Club, the steps differ, so ask us what your city needs.
Related pages
If you’re planning a new slate or tile roof, see our slate roofing in Westlake and tile roofing in Southlake pages. For a modern metal look, our standing seam page for Colleyville covers that option, and our gutter services page covers gutter replacement.
Get your valleys and flashings looked at
If your slate or tile roof has a leak near a valley, chimney or wall, or you’re planning a roof and want copper details done right, let us look at it. Our Rhome office is about 27 road miles from Colleyville, and we work on slate, tile and copper across the DFW Metroplex. We’re certified with major manufacturers including GAF, CertainTeed, Owens Corning, Atlas, Johns Manville and Carlisle. Request a free inspection or call (817) 733-9228.
