Related Topics ) describing procedures for evaluating the condition of slate roofing. How to inspect, identify defects, and estimate remaining life of slate roofs are addressed. The article also references slate repair procedures, repair slate sources, and slate quarries. The main article reviews types of slate, common defects, inspection topics, and some repair tips. Also see How to Inspect & Repair Slate Roofs for a detailed article about evaluating the condition of slate roofing and repairing worn or damaged slate roofs." />
Question? Just ask us!
Free Encyclopedia of Building & Environmental Inspection, Testing, Diagnosis, Repair
InspectAPedia ® Home
ROOFING INSPECTION & REPAIR
AMERICAN CEMWOOD ROOFING
BEST ROOFING PRACTICES
BUILT UP ROOFS
CATHEDRAL CEILING VENTILATION
CERTIFICATIONS for ROOFING CONTRACTORS
CHIMNEY FLASHING Mistakes & Leaks
COLD WEATHER ROOF TROUBLE
DECKS, ROOFTOP CONSTRUCTION
EPDM, RUBBER, PVC ROOFING
EXTRACTIVE BLEEDING on SHINGLES
FIRE RETARDANT PLYWOOD
FLASHING on BUILDINGS
FLAT ROOF MOISTURE & CONDENSATION
Green House or Solarium Roof Leaks
HEAT TAPES & CABLES on Roofs for Ice Dams
ROOF ICE DAM LEAKS
MASONITE WOODRUF FIBERBOARD ROOFING
NOISE CONTROL for ROOFS
PLASTIC ROOFING TYPES
PVC, EPDM, RUBBER ROOFING
ROOF ARCHITECTURAL STYLES - PHOTO GUIDE
ROOF CLEANING RECOMMENDATIONS
ROOF COLOR RECOMMENDATIONS
ROOF INSPECTION SAFETY & LIMITS
ROOF LEAK DIAGNOSIS & REPAIR
ROOF NOISE TRANSMISSION
ROOF REPLACEMENT SNAFUs
ROOFING FELT UNDERLAYMENT REQUIREMENTS
ROOFING MATERIALS, Age, Types
SADDLE CONSTRUCTION at CHIMNEYS
SNOW GUARDS & SNOW BRAKES
STANDARDS for ROOFING
STRESS SKIN INSULATED PANELS
TEST LABS - ROOF SHINGLE
TREES & SHRUBS, TRIM OFF BUILDING
TRUSSES, Floor & Roof
UNDERLAYMENT REQUIREMENTS on ROOFS
VENTILATION in BUILDINGS
WALK-ON ROOF SURFACES
WARRANTIES for ROOF SHINGLES
WORKMANSHIP & ROOF DAMAGE
Worn-out slate roof indicators: how do we decide that the roof is beyond economical repair? Here we provide photos of worn-out slate roofs that are beyond repair. This slate roofing photo library shows various kinds of roofing slate, slate roof colors, slate roof patterns, and roofing slate defects. This photographic dictionary of roofing slates is a supplement to our detailed article (links at Related Topics ) describing procedures for evaluating the condition of slate roofing. How to inspect, identify defects, and estimate remaining life of slate roofs are addressed. The article also references slate repair procedures, repair slate sources, and slate quarries. The main article reviews types of slate, common defects, inspection topics, and some repair tips. Also see How to Inspect & Repair Slate Roofs for a detailed article about evaluating the condition of slate roofing and repairing worn or damaged slate roofs.
Green links show where you are. © Copyright 2014 InspectApedia.com, All Rights Reserved.
Slate is essentially a complex mineral or stone product - so how could slate actually "rot".
Well it doesn't. Not quite anyway. (Though slate, as a naturally occurring mineral, can include soft inclusions, even organic debris, slate is basically stone. Minerals don't rot.)
But depending on their composition (each slate quarry has a unique chemical signature that identifies its slates), slates can become soft, crumbling, or delaminated that on touching a slate it is found to be completely softened and thus completely at or past the end of its life.
Below I illustrate this condition in three photographs.
As we discussed in more detail at SLATE ROOF INSPECTION & REPAIR, determination of slate condition other than by direct up-close inspection is highly unreliable. Slates may look fine from the ground, but be found soft and at end of life on close inspection.
By direct inspection we mean looking at slates from a few inches, either from a ladder or some other point of view such as an attic window. We strongly advise inspectors not to walk on slate roofs whether they look soft or not. Soft Deteriorated Roofing Slates may not be obvious from the ground but mean the roof is at end of life.
Examples of slate roofs in poor or worn-out condition
Poor condition slate roof, many loose slates, efflorescence almost fills upper slates, many thin delaminating slates, more than 25% of this roof is bad, beyond economical repair.
Watch out: don't confuse superficial or light surface delamination that appears on the surface of roofing slates that remain in good condition with delamination that indicates that the whole slate is soft and shot.
It often requires an up-close look and probably some gentle "touching" or probing for a roofer or roof inspector to conclude with confidence that slates are in good condition with surface delamination versus in poor condition and worn out. See DELAMINATING for clarification. This point of confusion is another argument that a "roof inspection" performed only from the ground is, of necessity, incomplete.
Poor condition slate roof - close up, of a roof beyond economical repair (using slate) - a patch and struggle policy may be tolerable.
The dark colored slates are areas where bad slates have been replaced.
We'd love to see this replacement pattern continue. Many roofers opine that when more than 25% of the slates have to be replaced in a short period, the roof is beyond economical repair.
Worn slates at or near end of life, in the upper roof - note the efflorescence on some slates and the delaminating slates. Some slaters inform us that when they see the efflorescence marks on slates having nearly completely covered the slate they guess that the slate is near the end of its life.
Some slates, such as the red slates shown in photos above, do not show this efflorescence pattern, probably because the composition of that stone resists moisture absorption better than the darker slates shown in this photo.
Worn slates at end of life, lost slates, delaminated slates, broken slates on this small roof make re-roofing necessary
Worn out slates and sliding slates, on a slate roof beyond economical repair
Sliding slates, failed nails, and rotted roof sheathing show that this roof has not been maintained for a decade or more. Thin delaminated slates are worn out.
This roof is already leaking and is covered by slates that include so many soft, loose, lost-fastener & broken, or missing roof slates over soft rotted roof decking (more visible from the attic side) that the roof is beyond repair.
Questions & answers or comments about wear indicators on slate roofs - how do we conclude that a slate roof is worn out or is beyond economical repair?
Try the search box just below or if you prefer, post a question or a comment in the Comments box below and we will respond promptly.
Search the InspectApedia website
Related Topics, found near the top of this page suggest articles closely related to this one.