Envelope and protection · Roofing
Reclaimed Roofing Slate & Tile
This entry describes reclaimed roofing units as a supply and sorting question rather than a product one, and sets out what has to be established about material whose history is unknown before it is laid again.
Educational reference entry. Suitability depends on the complete assembly, substrate, exposure, installation method, manufacturer documentation, local requirements and qualified professional review.
Overview
What reclaimed slate and tile is
Reclaimed roofing slate and tile is covering material taken off an existing roof, cleaned, sorted and offered for re-use. It is not a manufactured product with a specification behind it: it is a quantity of second-hand units whose origin, age, exposure and previous fixing are usually only partly known. The library publishes it separately from new quarried slate and new fired tile for the same reason it publishes reclaimed brick and reclaimed timber flooring separately — the subjects that matter are variability, history and quantity, and a new-product entry cannot carry them.
The material arrives as a batch rather than as a specification. Within one delivery, thickness varies, size varies, colour and weathering vary, and the proportion that is actually sound varies too. Sorting is therefore part of the work rather than a preliminary to it: units are graded by thickness and size so the heavier ones can go low on the slope, sounded for delamination and cracks, and set aside where they are unusable. A yard may have done some of that already, or none of it, and knowing which is a question rather than an assumption.
Old units carry old holes. A slate that was nailed at the head on one roof may need holing at a different point for a different gauge on the next, and re-holing a brittle unit is itself a source of breakage. Clay tiles carry their nibs and nail holes from their first life, and a nib that has broken away changes how the tile hangs. The proportion of a batch that survives sorting and re-holing is not known until it is done.
Quantity is the constraint that runs through everything. A reclaimed batch is finite, it cannot be topped up from the same source, and whether a shortfall could be made up from elsewhere is unknown until it is sought. That reverses the usual order of decisions: the quantity available fixes the area that can be covered, the gauge and the mixing strategy, rather than the design deciding how much to order. Mixing salvaged and new units on one slope, or using reclaimed on the visible elevations and new elsewhere, is a design decision made openly rather than a compromise discovered halfway through.
Terminology
Common names and aliases
These names describe the same thing. The library keeps one entry per material so that an acronym, a trade name or a regional spelling never becomes a second, thinner page.
- Salvaged roofing slate
- Second-hand roof tiles
- Salvaged clay roof tiles
- Reclaimed roof covering units
Applications
Common applications
Where this material is typically encountered. A typical application is not a statement that it suits your project.
- Repairs and patch renewals to an existing slate or tile roof where matching the existing covering matters.
- Re-covering a roof in a setting where the appearance of weathered units is part of what is being kept.
- Extensions and additions to an older building where the new roof is to read with the old one.
- Outbuildings, porches and small roofs where the quantity needed is within what a batch can supply.
- Roofs where the original covering is being stripped, sorted and relaid with new units making up the shortfall.
- Conservation and repair work where re-using the existing material is the starting point for the discussion.
Consideration
Where it is commonly considered
- Where an existing weathered roof has to be matched and new units would read as obviously new.
- Where the original covering is coming off anyway and re-using the sound part of it is being discussed.
- Where the quantity required is modest enough that a single batch can plausibly cover it.
- Where someone with experience of sorting and grading salvaged units is involved in the work.
- Where re-use of existing material is a stated aim of the project and its consequences are accepted.
- Where the roof structure has been examined and what it carries is understood.
Professional review
Where additional professional review is especially important
These are the situations where the answer depends on the specific building, and where a qualified professional should be involved before anything is decided.
- Where the quantity available has not been counted and the design assumes more than the batch holds.
- Where nothing is known about the condition of the units and no sorting or sounding has been done.
- Where the roof structure has not been examined, since reclaimed units vary in weight and the existing structure's capacity is a structural question.
- Where the units would be laid to a gauge or pitch different from the one they came off, and nobody has considered the consequences.
- Where salvaged and new units are to be mixed on one slope and no one has decided how.
- Where the provenance of the material cannot be established at all and that matters to the project.
Properties
Key properties to discuss
Qualitative topics worth raising. Measured values, classes and grades come from the manufacturer's technical documentation for the specific product, not from a reference page.
- Documentation
- What is known about where the units came from, what has been done to them and how many there are is the whole substance of the transaction. Unlike a new product, there is no specification standing behind them, so the record that does exist is worth asking for.
- Substrate dependency
- Batten gauge, the spacing of supports and the way the units were originally fixed all belong to the roof they came from. Laying them on a different roof means the gauge, the fixings and the holes are reconsidered rather than copied.
- Weathering and exposure
- Every unit has already weathered, and unevenly. Faces that were exposed differ from faces that were sheltered, and a sorted batch still varies in colour and surface across the slope.
- Repairability
- Re-using salvaged material is itself the repair strategy for many older roofs, but a batch cannot be added to. Keeping a reserve of sound units aside for future repairs is a decision made when the roof is laid rather than afterwards.
- Installation dependency
- Sorting, grading, sounding and re-holing are part of the labour, and they are not quick. Breakage during sorting and during laying is normal and is allowed for rather than treated as a surprise.
- Moisture behaviour
- A delaminating slate or a frost-damaged tile admits water where a sound one does not, so the soundness of individual units, rather than the material family, is what matters here.
- Appearance
- The variation is the reason people choose reclaimed material, and it is also the thing that has to be managed: how the batch is distributed across the slope decides whether the roof reads as weathered or as patchy.
- Maintenance
- Future repairs depend on finding compatible units, which is easier where a reserve was kept and where what was laid was written down.
Exposure
Exposure and environmental conditions
- How exposed is this roof, and were these units taken off something comparable?
- What pitch were they laid at before, and what pitch are they going onto now?
- Is the setting one where the weathered appearance of salvaged units is part of the point?
- Does the roof sit under trees or in a damp position where growth will take hold quickly?
- Are the units going onto a slope that faces a different direction from the one they came off?
Assembly
Substrate and system dependencies
What this material sits on, is fixed to or depends on. This is usually where performance is won or lost.
- Battens, their spacing and the gauge the units will be laid to follow from what the batch actually is, not from a standard arrangement.
- The underlay and ventilation of the roof are designed for this roof rather than inherited from the previous one.
- The existing roof structure's ability to carry the covering is a structural question for qualified professionals, especially where the previous covering was different.
- Fixings are selected for the units as they are now, including where old holes cannot be re-used.
- Where reclaimed and new units share a slope, the way they are distributed is a decision recorded before laying begins.
- Flashings, valleys and abutments are detailed for the units being laid rather than copied from the donor roof.
Appearance
Appearance and finish considerations
- Variation in colour, thickness and surface across a batch is inherent, and the roof reads as a range rather than as one tone.
- Distributing the batch deliberately across the slope, rather than laying it as it comes, is what keeps a roof from looking patched.
- Weathered units set against new ones are plainly different, and that contrast does not close up quickly.
- Units graded by thickness are commonly laid with the heavier ones lower on the slope, which reads as a subtle change up the roof.
- Moss and lichen already present on salvaged units carry over onto the new roof, which some projects want and others do not.
Durability
Durability questions
Questions to raise rather than a service life to expect. No material has a universal lifespan — it depends on the assembly, the exposure and the upkeep.
- How was this batch sorted and sounded, and by whom?
- What proportion of the batch was set aside as unusable, and on what basis?
- Are the units being re-holed, and what does that do to breakage?
- Is a reserve of sound units being kept aside for future repairs?
- What is the condition of the roof structure that will carry them?
Upkeep
Maintenance and repair considerations
- Where would matching units come from if repairs are needed in a few years?
- Has a reserve been set aside on site, and where is it being kept?
- Has what was laid — the source, the type and the gauge — been written down anywhere?
- How will individual broken units be replaced without disturbing those around them?
- Who would be called on to work on a roof of this kind later?
Installation
Installation dependencies
What the installation depends on — not how to do it. Method belongs to the manufacturer's instructions and the trades carrying out the work.
- Sorting, grading and sounding happen before laying and take real time, which belongs in the programme rather than being absorbed.
- Re-holing brittle units causes breakage, and an allowance for that is made openly rather than discovered.
- The gauge is set from the units actually available, so the batch is counted and measured before the roof is set out.
- Where the quantity falls short, the strategy for making it up is decided before laying starts rather than mid-slope.
- Handling and stacking of salvaged units matters: material that survived a century on a roof can be broken in a day on the ground.
- Where the existing covering is being stripped for re-use, the stripping method decides how much survives.
Documentation
Documentation to request
Ask for these in writing, for the specific product being proposed, and keep them with the project record.
- Whatever is known about the origin of the batch and the building it came from.
- A statement of what sorting, cleaning or grading has already been carried out, and by whom.
- The counted quantity available, and whether any more can be obtained from the same source.
- A record of what was laid on this roof, including the gauge and the fixings used.
- Where units are being re-used from the building itself, the record of what was stripped and what survived.
Conversations
Questions for qualified professionals
Bring these to the relevant qualified professional, manufacturer or authority. Requirements vary by project and location.
- How many sound units are actually available, and who counted them?
- What has been done to sort, sound and grade this batch, and what was rejected?
- Is the existing roof structure able to carry this covering, and who has confirmed that?
- What gauge are these units being laid to, and how was it arrived at?
- Are the old holes being re-used or are the units being re-holed, and what breakage is expected?
- If the batch runs short, what is the plan, and has it been agreed before work starts?
- How will reclaimed and new units be distributed if both are being used?
- Is a reserve being kept for future repairs, and how much?
- What is being written down about this roof for whoever works on it next?
Blind spots
Commonly overlooked points
- The quantity available fixes the design rather than the other way round, and a batch cannot be topped up.
- Sorting, sounding and re-holing are a substantial part of the labour and are routinely underestimated.
- A batch that looks uniform in a yard rarely is; thickness and size variation shows up as soon as it is laid.
- Breakage during sorting, re-holing and laying is normal, and an allowance for it belongs in the quantity from the start.
- Keeping a reserve of sound units aside is the one future repair decision that can only be taken now, while the material is still on site.
- Re-using salvaged material does not remove the need to look at the structure carrying it.
What this page does not do
- This page states no strength, no soundness and no durability for any salvaged unit: condition is established unit by unit, by qualified professionals, on the batch actually supplied.
- Whether an existing roof structure can carry a covering of reclaimed units is a structural determination for qualified professionals and is never inferred from what the roof carried before.
- Nothing here establishes provenance, legality of salvage or freedom from hazardous material in any batch; those are matters for the parties to the supply and for local requirements.
- Local requirements govern what may be used on a roof in a given place, including in designated areas, and they are confirmed with the relevant authority.
Related entries
Often used alongside
Entries commonly encountered together with this one. Co-occurrence only — never a claim that any combination is compatible or suitable.
Inspiration
Related Ideas Library pages
Design directions where this material commonly appears.
Preparation
Related planning checklists
Owner-side preparation before the conversation where this material comes up.
Go deeper
Related Build Design Hub guides
Planning guidance and neutral comparisons behind the decisions on this page.
Roofing Materials & Systems
Reference entries for roof coverings and roof waterproofing — tiles and slates, shingles, sheet and standing-seam metal, single-ply and built-up membranes, liquid systems and green roofs.
Browse all roofing entries →