Reclaimed slate and clay roof tile can bring a depth of color, texture and age that is difficult to reproduce with newly manufactured roofing.
Much of this material was originally made to last for generations. When carefully removed, sorted and properly reinstalled, reclaimed roofing can often continue serving as both a functional building material and an important architectural element.
Unlike new roofing, however, reclaimed material should be evaluated piece by piece. Condition, dimensions, previous exposure and remaining service life can vary within a batch.
Before You Purchase
Determine the approximate roof area and quantity required before purchasing.
Reclaimed roofing is typically available as a finite batch. Matching the exact color, profile, dimensions and weathering of an existing batch later can be difficult.
We generally recommend purchasing additional material beyond the calculated roof quantity for sorting, cuts, breakage during installation and future repairs. The appropriate overage depends on the material, roof complexity and condition of the batch, so final quantities should be reviewed with the roofer.
Before ordering, confirm:
- Slate or clay tile
- Approximate dimensions
- Thickness
- Clay tile profile
- Quantity available
- Existing nail or fastening holes
- General condition
- Roof pitch
- Required exposure and overlap
- Roof area and complexity
- Availability of matching ridge, hip or specialty pieces
Whenever possible, have the roofer review samples and dimensions before purchasing a large quantity.
Expect Variation
Variation is inherent in reclaimed roofing.
Slate may vary in thickness, color, texture, edge condition and weathering. Clay tile may vary in color, firing, dimensions, curvature and surface texture.
Expect some pieces to show:
- Chips
- Worn edges
- Old fastening holes
- Surface deposits
- Mineral staining
- Moss or biological staining
- Color variation
- Previous weather exposure
Some variation is cosmetic. Other conditions can affect whether an individual piece should be returned to service.
The material should be sorted before installation so questionable pieces can be removed and color, thickness and weathering can be distributed intentionally across the roof.
Inspect Every Piece
Reclaimed roofing should not simply be moved from a pallet directly onto the roof.
Each piece should be inspected before installation.
Slate should be checked for significant cracks, delamination, softness or deterioration. Experienced slate roofers will often sound individual pieces by gently tapping them to help identify potentially compromised slate, although visual inspection and installer experience remain important.
Clay tile should be checked for significant cracks, fractures, spalling and deterioration around fastening points.
Pieces that are questionable should be set aside rather than installed in critical areas.
Know Your Material
Not all slate and clay tile perform the same way.
Natural slate varies according to its geology and source. Some slate is exceptionally durable, while other material may be more susceptible to delamination, mineral inclusions or weathering.
Clay tile also varies considerably according to its original composition, firing and manufacturing method.
Whenever provenance or manufacturer information is available, Green Pirogue will provide it. With reclaimed material, however, the exact quarry, manufacturer, age or original performance specification may not always be known.
Unless specific testing or documentation is provided, reclaimed roofing should not be assumed to carry the same certifications, warranties or tested performance ratings as newly manufactured roofing products.
Measure the Actual Material
Do not design the roof solely around nominal dimensions.
Reclaimed slate and clay tile may vary slightly in size, thickness or profile, even within the same batch.
The roofer should review actual material before determining exposure, overlap, coursing, fastening and layout.
This is particularly important around:
- Eaves
- Ridges
- Hips
- Valleys
- Dormers
- Chimneys
- Roof penetrations
- Changes in roof pitch
A small dimensional difference repeated across many courses can become significant by the time it reaches the ridge.
Roof Structure
Slate and clay tile are considerably heavier than many common roofing materials.
Before installing reclaimed roofing, the roof structure should be evaluated to confirm that it is appropriate for the anticipated dead load and roof assembly.
This is especially important when replacing a lighter roofing material with slate or clay tile.
The appropriate project professional should determine whether structural review or reinforcement is necessary.
Underlayment & Water Management
The visible roofing material is only one part of a successful roof.
Underlayment, flashing, valleys, penetrations, drainage and transitions should be designed as a complete water-management system appropriate for the roof.
The fact that the slate or tile is historic does not mean the concealed roof assembly should be.
Modern flashing and water-management practices can be incorporated while preserving the appearance of traditional roofing.
Particular attention should be given to valleys, chimneys, dormers, walls, penetrations and other locations where water is concentrated.
Installing Reclaimed Slate
Natural slate should be installed by a roofer experienced with traditional slate roofing.
Slate installation requires careful attention to headlap, exposure, fastening, sorting and layout.
Existing nail holes may sometimes be reusable, while other installations may require new fastening locations. Slate should not be over-nailed or fastened so tightly that natural movement is restricted or the material is damaged.
Fasteners should be selected for the roof assembly and expected service life.
Slate thickness should also be considered during sorting. Mixing substantially different thicknesses without planning can create an uneven finished surface and installation difficulties.
Installing Reclaimed Clay Tile
Clay tile installation depends heavily on the particular profile and fastening system.
Historic tiles may have been nailed, wired, clipped, hung from lugs, set in mortar or installed using a combination of methods.
The roofer should inspect the actual tile before determining the new installation method.
Tile should be properly supported and secured for the roof pitch, exposure, substrate and local wind conditions. Do not assume the original installation method is appropriate for the new building.
Special attention should be given to ridge, hip and perimeter conditions where fastening requirements may differ from the field of the roof.
Ridge, Hip & Specialty Pieces
One of the most important things to consider before purchasing reclaimed roofing is whether the batch includes the necessary specialty pieces.
Historic roofs may use dedicated:
- Ridge tiles
- Hip tiles
- Starter pieces
- Eave pieces
- Half tiles
- Ventilation pieces
- Decorative finials
Exact matching pieces may be difficult to source later.
If original specialty pieces are unavailable, the roofer and designer should determine how these conditions will be resolved before installation begins.
In some projects, compatible new pieces, fabricated metalwork or carefully selected reclaimed material can be incorporated without compromising the overall appearance.
Flashing
Good flashing is essential to the longevity of any slate or clay roof.
Copper and other durable sheet-metal flashings are commonly paired with long-life roofing materials, but the appropriate flashing material should be selected for the specific project and surrounding materials.
The expected life of the flashing should be considered alongside the expected life of the roof itself.
Installing a long-lasting reclaimed roof over short-lived flashing can create unnecessary future work.
Walking on Reclaimed Roofing
Slate and clay tile can be damaged by improper foot traffic.
Once installed, access should be limited to people familiar with working on these roofing systems. Walking directly across slate or clay tile without the appropriate techniques and equipment can crack otherwise serviceable material.
Future contractors working on chimneys, gutters, HVAC equipment or other roof penetrations should be made aware of the roofing material before accessing the roof.
Cleaning
Reclaimed roofing does not need to look new.
Weathering, mineral deposits and subtle color changes are often part of what makes old slate and clay tile desirable.
Avoid aggressive pressure washing, grinding, blasting or harsh chemical cleaning unless the method has been evaluated for the specific material.
If cleaning is desired, test the proposed method on several pieces first.
Repairs & Future Maintenance
One advantage of traditional slate and clay roofing is that individual pieces can often be replaced without replacing the entire roof.
Keep a supply of matching material after installation whenever possible.
A small stock of original pieces can make future repairs considerably easier and help avoid visibly mismatched replacement material.
Periodic roof inspections should focus on broken or displaced pieces, flashing conditions, penetrations, valleys and other areas where water enters or concentrates.
Choosing a Roofer
This is one material where installer experience matters enormously.
We strongly recommend using a roofer with demonstrated experience installing and repairing natural slate or traditional clay tile roofing, depending on the material being used.
A contractor experienced primarily with asphalt shingles or modern concrete roofing tile may not necessarily have the specialized knowledge required for historic slate or clay systems.
The roofer should inspect the actual reclaimed material before installation and be comfortable making decisions regarding sorting, fastening, exposure, flashing and specialty conditions.
Order Enough the First Time
Reclaimed roofing is particularly difficult to match later.
Even another batch of the same type of slate or clay tile may have noticeably different color, dimensions, weathering or surface character.
Whenever possible, purchase enough material for the roof plus an appropriate reserve for future
