"Inspecting Slate Roofs" online video course

This thread is dedicated exclusively for those students currently enrolled in the InterNACHI online video course titled, "Inspecting Slate Roofs."
Students are free to pose questions and comments here and join in the conversation with other students. The thread will be monitored by the course instructor.

The Inspecting Slate Roofs online video course covers the following topics:

  • Structural and Architectural Metal Roofing
  • Energy State of Metals
  • Corrosion
  • Metals Used for Roofing
  • Naturally-Weathering Metal
  • Coating
  • Staining
  • Damaging Conditions
  • Defects
  • Installation
  • Wind Damage
  • Hail Damage

And, in keeping with InterNACHI’s commitment to Continuing Education, this course is open and free to all members, and can be taken again and again, without limit.

Contact: Director of Education, Ben Gromicko ben@internachi.org

Inspector training courses: www.nachi.org/education.

Thank you.

Has anybody passed this course recently?

Either there is a problem with the course’s grading calculation, or I am as dense as the slate we are learning about.


Roofs by far have been the one I have had to do far more review

Just starting this one.

The introduction to this slate roof course appears to be actually the introduction to the metal roof course.

Starting course now. :smiley:

Well I hope the calculating method is corrected here I go

Starting course

Hi it’s David from Harrishome inspection i’m starting the slate roof course and looking forward to it

Hi everyone:
A lot of the video information was able to clear up what I’ve been seeing with regard to slate roofs. Those telltale hooks , snow guards and repair clips now make sense as to why the seem random or not random. So many of the older homes are very steep slate roofs and now it is obvious why. It’s best that slate roofs get to shed water quickly.

In the process of taking the slate roof course and one of the requirements was to post a picture (here I believe) and describe the condition; which in this case is a loose slate tile, recommending evaluation for cause and repair by a qualified roofing contractor.

There were also several missing tiles, same recommendation.

Yes, I was up there grabbing tiles, but only from the eaves where I could reach them and view the mastic covered side wall step flashing.

Al in CT

Slate roofs come in Three types of slate standards, S1, S2, S3,…S1 being the best and lasting the longest, 75-100 years in some cases. Most times these long lasting roofs will outlast their underlayment, hangers and flashing. The life of copper flashing is about 70 years. Ribbon slate roofs are the least durable of all slate roof. Graduated slate roofs start with the thickest of slates at the Eaves and the thinnest at the ridge. Never Walk A Slate Roof!! You can slip and fall of roof or damage the roof beyond repair!

Slate roof on a early 1900 home. No obvious signs of loose or broken shingles.

Some shingles had small broken corners but roof was performing as designed with no moisture issues noted inside of home.


This is one of the rare slate roofs in our area. The house was built in the early 1950’s. No repairs were observed in the uniformly colored roof slate.

Mastering Roof Inspections: Photography gives a good overview concerning taking pictures of roofs with a digital camera. Inspectors may also opt to use their smartphone or tablet to take pictures instead of a separate camera. Quality pictures are a must. Being able to zoom in to help the client is crucial.

Mastering Roof Inspections: Slate Roofs, Part 1 is closely related to the early pages of this course. (No doubt that is why it is labeled part 1.:wink: ) It focuses primarily on the geography of slate location, color, and density. Good review.

Thank you for another good class. The pictures and video really help to make the content clear.


This is a picture of a slate roof. The roof seems be in good shape and and fully functional.

Mastering Roof Inspections: Slate Roofs, Part 1

Slate is natural and formed by accumulation of clay and sand. Fading slates may change color over time. Unfading slates will maintain their color for many years. High density slate is less absorbing. Moisture absorbtion is a major contributor to slate deterioration.

Mastering Roof Inspections: Slate Roofs, Part 2

The highest grade is slate is S1 and has a lifespan of more than 75 years. The lifespan of slate is definitely related to the quality of the slate. An inspector will not be able to tell the type of slate on sight alone.

Inspection Assignment:

Don’t currently have access to a slate roof so I will use a different item for my assignment.

Full inspection of the roof decking was not possible due to large amounts of tree debris on roof. Recommend keeping roof free of debris which will shorten the lifespan of the roof.

Roofing penetration is corroded and damaged. This is not only a source for moisture intrusion but pests as well. Recommend replacement by a competent roofing contractor and further evaluation of the roof after the clearing of debris on roof for the possibility of further damage not visible during the inspection.

The slate roof is in overall good condition. Step flashing could be seen at the sidewalls of the dormers. Metal valley flashing and metal hip caps are in good condition. Some of the slates are showing signs of delamination. Delamination is caused by the reaction of certain minerals to long-term moisture cycles. Over time, these minerals expand, causing layers to separate along cleavage planes. A number of slates have been replaced as indicated by the presence of slate hooks (see below). I did not see any missing or broken slates. Some efflorescence is also visible. This should be monitored as widespread efflorescence indicates a long-term moisture problem that may be serious.