Old cedar roof shingles with asbestos coating?

[Piper2022]

Old cedar roof shingles with asbestos coating?

I am tearing apart a 1910 vintage roof on our home and stumped on what I am dealing with for a material that was used to treat these cedar shingles back in the day. I am hoping someone can shed some light and maybe someone has ran into a similar material?

I have had two individual shingle samples analyzed by a local lab and one sample the coating contained 3% Chrysotile Asbestos where the other shingle contained zero %. As of this moment I have a dozen more shingles in route to the lab for further analysis to get this figured out. The lab manager has never seen an asbestos containing material such as this!

The roofing layers are as follows:
1. Newer corrugated light gage roof that was installed in 2002. The only reason we are removing some of this is due to a big addition project.
2. Older corrugated thick gage roof installed with ring shank nail with lead heads on the nails. This layer is in very bad condition(rust). I am thinking 1950's or 60's vintage.
3. White cedar shingles nailed right to the sheathing boards, no tar paper. These were nailed on with small smooth shank round nails only about 1" long. Much smaller than the siding nails we use today.


So... The interesting thing here is the light and dark stained coating on these shingles. When intact on the back of shingles it looks and feels like an oil based polyurethane with some darker hues in spots(which did not exist 100 or more years ago). The front side of the shingles that were exposed to the elements, the coating is nearly non-existent. Another observation is this finish was applied much after the original install as it weeped around the nail holes extensively.
I am very familiar with roofing tar products and this does not look like any of the typical tar products that to my knowledge would be much thicker.

I have been chatting with some old timer carpenters I know and they said we used and they have seen creosote used back in the day and from what they can see it looks like a creosote wood preservative.

Has anyone seen anything similar or know what might have been used on these?

Thanks!

 

[bmaverick]

So... The interesting thing here is the light and dark stained coating on these shingles. When intact on the back of shingles it looks and feels like an oil based polyurethane with some darker hues in spots(which did not exist 100 or more years ago).

Has anyone seen anything similar or know what might have been used on these?

Thanks!

Back then whale oil or castor oil was used. Duck oil, Danish oil, linseed oil, tung oil (from nuts) were used back then too.

Those are the pre-polyurethanes from long ago.

Asbestos shingles do exist too.

Should You Worry About Asbestos in Shingles? | RoofCorp of Metro Denver, Inc.

Asbestos is a naturally occurring substance that can cause serious health issues when inhaled. Learn What to Worry About with Asbestos in Shingles in this blog.

www.roofingexperts.com

 

[Roadworthy]

My father in law had a hundred year old plus farm house the family lived in. He had a cedar (I think) shake roof. He'd go up every few years and put on a new coat of oil, don't know what kind. The house still had the same roof when he retired and sold the farm.

 

[Dwellonroof]

A cedar shingle roof is a true 3 ply meaning it has 3 layers plus the headlap.

 

[EddieWalker]

I can't comprehend a reason for asbestos to be applied to a cedar shingle. Is there a chance that the shingle was next to something that contained asbestos? Pipe insulation? Siding? some sort of tile?

 

[/pine]

There is an upscale community near here that has building restrictions that require ALL roofs must be cedar (wood) shake shingles...Even a dog house must have a shake roof...by law said wood shingles must meet fire proof treatment regulations...

 

[ponytug]

Some roofing felts were made with asbestos back in the day, and there were certainly roof cements with it. I wonder if the original "felt" just decomposed and adhered to the cedar over the years. The metal roof on top of the cedar would have acted like an oven to really bake any petroleum product under it.

I grew up in a home covered in cedar shakes, and every few years we (I) would spray the shingles to saturation with a mix of linseed oil and paint thinner (1:1), the latter to help the penetration. It was locally known to be good practice to prevent rotting/ageing, especially on poorly designed roofs that didn't have ventilation on the back side of the cedar shingles to dry them out and keep them from rotting.

I would guess that the repeated oil treatments over the years caused some of the asbestos to transfer and adhere to the cedar shingles. The heat would have made it worse. As far as I am aware, there wasn't a cedar/asbestos roofing shingle that was widely sold, but I certainly don't have full knowledge of every shingle ever made.

All the best,

Peter

 

[Dwellonroof]

Should not have felt under a wood shingle roof.