Slate Roof Condition

Eflorescence almost fills the upper slates and there are many thin delaminating slates.

Slate roof condition.

Some slates have been known to last over 200 years. Examples of slate roofs in poor or worn out condition this poor condition slate roof sports many loose slates. However as long as the slates are physically intact the roof is serviceable. On a residential building the maximum weight per square you d probably find would be 2500 pounds.

A slate roof can weigh as little as 700 pounds per square up to 8000 pounds where 2 thick slates were used on a graduated slate roof. The moisture retained in the slate can also begin to cause the wood roof deck to rot especially if the original felt underlayment is in poor condition. More than 25 of this roof is bad beyond economical repair. Sample roof condition report slate roofing this is an example of an actual roof condition report.

Installed properly slate roofs require relatively little maintenance and will last 60 to 125 years or longer depending on the type of slate employed roof configuration and the geographical location of the property. It should be considered a temporary unreliable repair. If the condition is typical and widespread it is likely time to replace the roof lest more shingles continue to slide down slope or the shingles become subject to blow off in high winds. The white visible in pennsylvania slate is evidence of efflorescence lime deposited on the slate surface.

The addition of slate to a house not framed for this purpose will require an analysis of the roof framing system. The roof survey of multiple slate roofs was performed by professional roof consultants. Tar or roofing cement should not be found at chimneys sidewall flashings plumbing vents or elsewhere. If the whole slate is white in color and scaling you should consider the slate to be at the end of its life.

It should be verified whether fastener corrosion is widespread or localized in areas subject to concentrated water flows such as below dormer valleys or below where a low slope roof drains onto the slate roof.