When did Tar and Gravel roofs come into existence? I am wondering what they used for roofing material on flat roofs in the old western towns in the 1800s. I have photos of those same buildings in the 1930s and they have tar and gravel on the flat roofs. But I can’t vision tar pots in action out in the wild west. Thanks.
Brent
Since it rains so infrequently out here in the “old western towns” they probably just had bare wood roofs that were not really flat, but had quite a slope to them.
If John Ford’s “Union Pacific” movie is an accurate indicator, corrugated metal sheets were available back then for use on rooftops.
The use of tar goes way back. English sailors are nicknamed “tars” because tar was so commonly used to waterproof Royal Navy ships for centuries. IIRC North Carolina back in colonial times was a major source of tar for ships - hence the nickname “tarheels”. But use of tar goes back to Roman times I believe. You certainly could see tar on roofs in the 19th century, but my guess is it would most likely be tarpaper rather than tar with gravel. I guess I’d look at getting the new Carstens book on the old west or other sources to see what they say.
Well I couldn’t sleep last night so I did some more surfing for the information. There was nothing in Wiki but many pages in on my Google search I finally found an article.
Though tar has been around for a long time, it never worked for roofs until gravel was added. The first successful T & G roof was in 1904 on the building owned by the guy who came up with the idea to use tar and gravel for roads thus replacing cobblestones, bricks and such.
I still haven’t found when Tar Paper came about. My guess is that as posted above, steel and Tar Paper were used in the 1800s.
It’s the flat roofs I am most curious about. Maybe they stretched canvas over them.
Brent
Nineteenth century western, “flat-roof” building (Columbia, CA).
The “flat roof” would have a slight slope so water would drain off (typically sloping toward the rear as in the case of this building).
Don’t see why they would put gravel on the roof. That wouldn’t aide waterproofing and could be a source of eventual leaks if people ever walked on the roof. But perhaps for wind protection?
Perhaps the early “tar paper” roofs were wooden roofs top-sheathed with canvas and then coated with a layer of tar.
Living under a flat roof makes me want to change building regulations that would prohibit them. Such roofs are always “itching” for a leak, especially “bathtub” roofs like the Wells Fargo building (where the roof is below the level of the walls.).
Mark
That’s a great old building Mark. Thanks for posting.
According to the article I read, the reason for the gravel was to protect the tar from the sun.The Sun would break down the tar quite quickly unless it was covered in gravel. Also gravel tended not to blow away. It also explained that they could never get a Tar road to hold together for the same reasons until a healthy amount of gravel was mixed in and on top.
Brent
Classic Miniatures makes an HO-scale kit of that structure (Walthers 225-38905 Wells Fargo Express Office.) I built such a kit about 20 years ago.
Mark
Tar and gravel has been used on industrial roofing for many years. I worked in a printing press factoy in Chicago many years ago (back in the Sixties), which had been there for at least 50-75 years before that. It had a tar & gravel roof, and people walked on it… I used to go up there on lunch breaks and watch the trains in the huge freight yard across the street… like sitting on a gravel road… They used pea gravel over the tar…
Mark,
Actually flat roofs work very well. As noted they are not really flat but have a slight pitch in one or more directions.
Flat roofs do require waterproof coatings such as hot applied tar or tar and gravel.
In fact, skylights work better and are less likely to leak in a flat roof than in a sloped shingle roof.
The prefered covering for flat roofs today is EPDM rubber membrane. A UV resistant rubber sheet, 45 mils or 60 mils thick that is simply laid out over plywood or insulating foam. On small applications it is glued down. On large applications it is attached at its edges and allowed to float.
EPDM lasts 25-35 years and is easily spot repaired in the rare case of a leak. It’s whats on all those big box stores in the shopping centers.
But many older hot tar built up roofs and tar and gravel roofs remain in service all over the country.
The gravel actaually protects the tar from the sun and controls the water runoff rate. These roofs usually last about 15-20 years before needing recoating.
Built up hot tar roofs, where tar paper and hot tar are applied in about three layers of each, last about 7-10 years and than need a new “top coat” of hot tar. After about 40 years they usually need to be stipped off and redone from scratch.
For more than 100 years all the row house in all the east coast cities have had hot tar flat roofs, they work just fine. Even in snowy Boston, hot Charleston as well as Baltimore and Phily which can see both extremes. It was 100 in Baltimore yestersay, and this past winter we had 60" of snow in 10 days. Not one flat roof colapsed, and its likely more shingl
Mark, one more note, buildings like the one pictured, do not generally have a parapet wall in the back at the low end, only on the sides and front.
Some building do have parapet walls all around and then have a drain pipe system - it all works just fine as has for several hundred years or longer.
Sheldon
I had a tar and gravel roof on my house that lasted 45 years before it needed replacing. I went to the membrane or torch-on type as I was told by several roofers that the tar they get now won’t allow a tar and gravel roof to last more than 20 years or so. One thing I found with the new roof is that there is lot more noise when it rains unlike the old roof. I guess the raindrops were broken up by the gravel.
A roofer said that there are many commercial buildings with tar and gravel roofs over 60 years old and a couple a the university that are 80 years old. Wonder what was in the tar back then?
CN Charlie
I found a website that has some interesting information on historic roofing materials
http://www.nps.gov/history/hps/tps/roofingexhibit/introduction.htm
The section on Composition roofing deals with the tar and gravel (and sand) methods, and yes, they go way back into the 19th century. Note that when we say the word “tar” – that can mean both pine tar and fossil based tar. Tar paper would have the advantage of portability of course.
At one time the 19th century railroad depots on the Chicago & North Western still had their slate roofs, and I have seen old sheds with zinc roofs.
Dave Nelson
I am finding this discussion to be helpful. I am building an HO scale Walthers roundhouse kit (the smaller one) and have been wondering what color to paint the roof panels. The panels have a texture to them, which might be tar and gravel or some other kind of tar based covering. Since I am assuming the Walthers kit represents a roundhouse that could have been build in the 1910-20 time period, having a tar and gravel roof should be appropriate. And then of course, what would be the “right” color for gravel? Thanks
David
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