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Photograph of really worn out asphalt roof shingles Lead Roofing Metal Uses & Effects

Lead roofing covers, flashings, materials guide:

This article describes and illustrates the use of lead on roofs both as the primary roof covering material and as roof flashings. We include photographs from several countries illustrating the durability of lead roofs. The article series also discusses the health & environmental effects of using lead roofing products and metals.

Shown at page top: lead flashing around chimneys and below a skylight on a fired-clay tile roof in Oslo, Norway. The flexibility of lead makes it an ideal flashing material when the flashing must adapt to curved or irregular surfaces such as the tile roof shown here.

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Effects of Lead in Roofing Systems

Lead roof on the Saxon Tower at St. Michaels in Oxford, England (C) Daniel Friedman

Shown above and below we see lead roofing atop the Saxon Tower at St. Michaels in Oxford, England in the U.K. Nearly a thousand years old, this is the oldest building in Oxford, dating from at least 1040 A.D., about the time of the Norman Conquest or shortly afterwards. Portions of the tower roof and access stair top are roofed in lead sheeting.

This tower probably served in defence of the north gate of the city of Oxford. The lead roof shown is, of course not quite so old. Its installers Parker and Slater dated their work with the placque shown below: 1765, making this lead roof over 200 years old.

[Click to enlarge any image]

Lead roof on the Saxon Tower at St. Michaels in Oxford, England (C) Daniel Friedman

Shown above is a closer view of how this lead roof is assembled. The lead panel edges are folded upwards, abutted together, and the raised seam is covered by the caps that you see as rounded ridges.

Soldered tabs hold the seam cap in place whiile allowing thermal movement among panels without buckling the roof. By the time this roof was installed, lead roofers had perhaps 800 years of experience. Well ... not individually.

Lead roof on the Saxon Tower at St. Michaels in Oxford, England (C) Daniel Friedman

We continue with additional examples of lead used in roofing.

Lead Panels Used on Steep Roofs

Lead roof on steep tower, Oxford, England (C) Daniel Friedman

The steep tower roof shown above, also located in Oxford, is sheathed in lead panels with raised seams.

This lead panel and raised seam approach is quite similar to the Parker/Slater lead use atop the Saxon tower. The seams are lead-soldered. The lead roof panel size was doubtless chosen for ease of working.

Lead Used on Flat & Low-Slope Roofs

Low slope roof covered with lead panels - Oxford (C) Daniel Friedman

Shown above, another Oxford lead roof, larger lead panels cover a low-pitched roof. These larger panels also use the folded, capped standing seam approach to permit movement and avoid leaks in the roof. Shown below is a second low-slope, large lead-panel-covered Oxford roof that is viewed from the top of the Saxon tower - a great place to stand for studying British roofs. Click to enlarge the image and you might also notice the lead-lined eaves-trough gutter at the lower end of this roof.

Low slope roof covered with lead panels - Oxford (C) Daniel Friedman

One of my favourite lead roof photos is this tile roof, also in Oxford and also viewed from the Saxon tower. The roofers have used lead to seal the flat ridge area of a tile roof, lead to provide step flashing and counter flashing against an abutting building masonry wall, and lead flashing also around a small skylight set into the tile roof.

Low slope roof covered with lead panels - Oxford (C) Daniel Friedman

Compelling evidence that lead salts washing down off of the roof, like copper salts in our copper roof photos, manages to dissuade algae, lichens, and fungal growth on the roof tiles themselves. Notice that where more metallic salt run-down is produced by the wider lead roof area a corresponding greater area of light coloured (clean) roof tiles are in view.

Lead Used on Roof Dormers

Roof dormer covered by a single lead panel, Oxford, UK (C) Daniel Friedman

Above the nearly-flat roof dormer has been covered with a single lead panel that extends up under slates and wraps around the side of the dormer roof sheathing.

Click to enlarge this photo for some other interesting details including lead flashing poorly installed around a plumbing vent - it laps only under the slates above the vent not under the slates at its side; the roofer who installed the dormer flashing took the same "put it on top" approach when flashing the dormer sides to the slate roof.

This detail is characteristic on older buildings into which plumbing was added later: nobody wants to have to pull off and re-install slates to get that plumbing vent in place.

An interesting additional vent, probably for a bathroom exhaust fan, is visible along the hip of this roof.

Lead Used as Roof Flashings

Lead chimney flashing, Oxford, U.K. (C) Daniel Friedman

Here lead was used for a beautiful chimney flashing job in Oxford; notice that the step flashing, mostly not visible, is under the roof tiles, the counter flashing seals the tops of the step flashing agasint the chimney, and the bottom of the chimney flashing at its down roof side brings water out to daylight. I'm not so sure about the barely-in-view dormer side flashing in the right of this photo: perhaps that was a different roofer.

Note: we don't know if any the more recent lead flashings shown in this article series are traditional pure lead or newer (and safer) terne-coated metal designed to resemble lead. - Ed.

Lead Coated Copper and Health Effects:

... modern terne-coated stainless steel or lead-coated copper might produce a more durable yet visually compatible replacement roofing. [2]

"Lead Coated Copper Metal (LCC): A Case Study of Public Health Addressing Regulatory Gaps", Thomas Plant, MS, Leon Bethune, MPH, John Shea, MS, Paul A. Shoemaker, MPH, Jose R. Diaz, John W. Weathers, and Charles Mba, MS. Environmental Health Office, Boston Public Health Commission, 1010 Massachusetts Ave, 2nd floor, Boston, MA 02118, 617-534-2644, tplant@bphc.org 2007 Abstract:

Lead coated copper (LCC) has become popular as a stain free replacement for copper in large renovation and new construction projects. The Boston Public Health Commission investigated the home of a child with an elevated blood lead level (EBLL) of 11ug/dl. LCC was used on the roof, flashing, and a wall around the ground floor patio.

The condominium interior was free of lead hazards. Sampling found lead dust levels of 224,377 mgs/ft2 wiped from the wall, 36, 441 mg/ft2 on patio, 79,400 mgs/ft2 under the roof drip line, and 11,517 mgs/ft2 at a roof drain to the patio indicating that the LCC was the probable source of the EBLL. Roof areas receiving runoff from the LCC had high lead levels while others had low levels.

This presented a unique problem because LCC is not paint and thus not addressed by the Massachusetts Lead Law.

Using the Massachusetts Public Health Nuisance Laws, an Abatement Order was issued to remove the LCC, but stayed for six months pending study by all parties. The LCC wall was removed, but roof runoff still contaminated the patio and building perimeter.

An encapsulant paint is being investigated to abate lead hazards by covering the LCC roofing. A survey found widespread use of LCC in Boston buildings including hospitals, universities, daycare centers, libraries, office buildings, hotels, and residences.

A Public Health Advisory was issued, the manufacturer removed LCC from the market, and city policy was developed to restrict the use of LCC on city-owned buildings.

Several queries about the effects of lead in roofing systems led us to find this 2002 Q&A offered by NRCA's Jack Robinson, RRC., Quoting:

Question: What are the advantages of using lead or lead-coated copper when installing standing-seam metal roof systems? Are there any government regulations that prohibit or limit the use of lead or lead-coated copper in roof systems? Also, will water that runs off a roof system made from either of these materials pollute groundwater?

Answer: Lead is a soft, common metal with several properties that are useful in roofing applications. Lead-coated copper is copper sheeting coated with lead on one or both sides.

Because lead is malleable, it easily is shaped at relatively low temperatures (70 F [21 C]) without the need for periodic annealing to soften the lead and make it workable. Lead sheets can be manipulated readily with hand tools and formed into complicated shapes. When used for flashings, lead sheets can be formed and adjusted easily in the field to accommodate substrate irregularities.

Lead also is corrosion-resistant. When left exposed, it develops a silver-gray patina that is insoluble in water. Because of the patina's insolubility, rainwater runoff over a weathered lead surface carries little lead or lead-based chemicals. Water runoff from lead surfaces will not cause stains to be deposited on adjacent building materials, such as stone, masonry or cladding.

Lead-coated copper has several advantages when used to form metal roof systems. It provides a durable finish that can be left exposed or painted, and lead coating is more compatible with paint than other metals. Lead-coated copper also is lighter than lead sheets, which reduces roof panels' weight contribution to a roof assembly's dead load. Lead-coated copper, unlike copper, won't stain adjacent materials. It also is easier to form than plain copper because the lead coating acts as a lubricant.

Both lead and lead-coated copper are durable roofing materials with longer estimated service lives than other common steep-slope roof coverings.

In recent years, publicity regarding the toxicity of lead-based paint has been widespread. Many people incorrectly have assumed any exposed lead is a potential health hazard or pollutant.

As previously stated, exposed lead sheets and lead-coated copper are not significantly soluble in water. The same property that prevents lead from depositing stains on adjacent materials also prevents lead or lead-based compounds from being washed off a roof system's surface and carried into groundwater.

Some manufacturers of lead roof coverings have attempted to respond to the public's concerns by providing calculations of lead contamination for specific projects. These calculations take into account a roof system area that will contribute to watershed, estimated average amount of rainfall at a project's location and lead's corrosion rate.

Several of these calculations indicate that the contribution of lead to groundwater attributable to water runoff from a lead roof system is one to two parts per trillion. The level at which the Environmental Protection Agency (EPA) imposes restrictions for lead in drinking water is 15 parts per billion (approximately 15,000 times less than the amount of lead contamination attributable to water runoff from a lead roof system).

According to EPA representatives, there are no regulations that restrict or prohibit the use of lead or lead-coated copper in roof systems. However, should a question arise about a specific project, contact your regional EPA office for additional information. A list of EPA's 10 regional offices can be obtained from EPA's Web site, www.epa.gov.

Additionally, some states may have regulations governing lead usage. To determine whether your state has specific requirements that regulate or prohibit the use of lead or lead-coated copper roof systems, contact your state's environmental protection agency.

Lead Roofing & Flashing Hazard Research

Metal Roofing Sources, Products, & Manufacturers

Best Practices Guide to Residential Construction lists these producers and sources of metal roofing, metal roof fastening systems, and related metal roofing products

- - Adapted with permission from Best Practices Guide to Residential Construction (Steve Bliss, J Wiley & Sons) .


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