OK, a question that’s been bugging me. I’m an electrical/electronic engineer, so I don’t really know civil engineering.
I look at houses that are abandoned and slowly fall apart, and the thing I notice is that they do OK until the roof gets a hole - even a small one - and then the process accelerates dramatically.
So, here’s my question: why are our roofs so easy to degrade? The roof on my house is made up (like everyone else’s) of shingles. Fairly constant maintenance is required. I have a friend in the South who just put in a metal roof, but it’s strips of lightweight metal. They tell me it lasts 50 years, but frankly I’m not so impressed (although they do like it that cell phones don’t work in the house, it’s quieter indoors).
Has anyone ever made a house with a stainless steel roof? I’m well aware that weight is a problem, but hardly an insoluble one. There’s always the cost issue, of course. But if you wanted to build a house that will stand for a long time, it seems to me that insuring the integrity of the roof is really important.
What are the problems (besides weight) with making a roof of a continuous sheet of stainless steel? Wouldn’t a house with such a roof last a very long time? Has this ever been designed or built?
I can’t find info on the Web on this point. Can anyone address this?
Interesting Idea. The standard for a long time was 20 years. Shingles now come with 30 and maybe 50 year guaranties. I have seen houses over 100 years old with galavanized steel roofs. As for weight, surely stainless steel would be less than slate.
copper sheeting makes roofs that will last far more than a century. copper creates its own protective oxide layer. with current methods each strip has a set of concealed anchors (under the next cover sheet) and has a double folded weather tight seam. copper is light weight and has been the historical method of choice for long lived roofs.
a single continuous roof would need to be anchored somehow. penetrations would compromise the roof. heavier sheets could be welded to supports and made into a single piece.
I’d like to note that the use of metal roofs varies greatly by region. I’d never actually seen a metal roof in person until I moved to (central) Washington state, where it was rare to see anything but. I’m pretty sure the same holds for Idaho, Montana, etc. I’m pretty sure it has a lot to do with lots of snow, which just slides off.
Colorbond steel roofing is common in Australia. Corrugated steel sheets coated in a sort of PVC paint. Some quick googling shows there is a stainless steel version of Colorbond, but I don’t know if it’s ever used for roofs.
I’m always amazed that any roof is still made of small tiles/shingles nailed in a configuration that excludes water. Even using metal sheets of handleable sizes a roof would be so much lighter and easier to fix. In this area (a conservation area of Cornwall UK) all domestic houses are required to have roofs of local slate, but all commercial buildings have no such constraints. All supermarkets and industrial buildings seem to be roofed in plastic coated steel. Also churches even here are often lead roofed and just one building i have seen has a rather hansom copper roof. (i understand copper is a popular roof and gutter materiel in German.)
Most of the larger commercial and industrial buildings here have the rubber or plastic single ply flat roofs. Wide sheets sheets are bonded together so the whole roof is one large sheet of rubber or plastic. I am not sure how big they can go that way. The old built up roof with the gravel ballast is mostly gone.
I asked about this some time ago here and people pointed out that continuous flat sheets of metal would have expansion problems and warping and buckling due to different temperatures in different areas. Don’t know how true it is, though. I think large tanks are made like this, though of course they are much heavier materials. But mobile home roofs are pretty much like this.
My grandfather, a somewhat successful inventor, decided that the best kind of roof for his new home would be cement. Metal, tile, asphalt – too wimpy for him. So when the second floor was finished, he placed a small, hand-cranked cement mixer in the attic and poured 2x2 foot cement blocks in a mold. The mold had his name in raised letters in the bottom so each block was imprinted that way. When solid, each block was lifted into place on a steel frame that he had built in his machine shop. It was a very heavy roof.
Then when they were done, it was discovered that the cement mixer was too big to remove thru the attic stairway, so they left it there. It’s still in the attic under the cement block roof since 1935.
They say the best way to destroy a house is to put a hole in the roof and just wait.
A lot of homes used to have tin roofs. They would last a long time, but they do rust. I don’t know if they ever rust completely through, I’ve seen some ancient homes with tin roofs but if the house is abandoned and falling down, the roof usually still looks ok.
My grandfather built a barn in the 1930s with a tin roof. It’s still in great shape and in my 33 years, I’ve never heard of it needing any repairs in the present or the past.
All roofs in this country (and all internal floors) are made of reinforced concrete; even slate roofs are just a layer of tiles over the real roof. This applies to private houses as well as apartment buildings.
Seconded; I think that movement is the biggest problem. The metal roof manufacturers that I’m familiar with recommend panels that are less than sixteen feet long to manage thermal expansion. In addition, buildings move, and a flat sheet might be pulled around as the roof moves, which in turn will cause leaks at the fasteners.
There is no need for continuous material for roofing unless dealing with a flat roof. Shingling is a time proven method of shedding water on a sloped surface. Roofs fail due to damage, improper installation and age.
Metal roofs are very common in British Columbia and are very durable.
Some posts back somebody mentioned tin roofs. I know in the more recent past galvanized steel was common. Were the metal roofs back 100 or more years tin? I have noticed a lot of careless usage of the words tin and galvanized.
For flat roofs, you can also get the continuous material with foam.
Metal roofs have some other advantages:
1 - Lightest possible weight. About 1/3 the weight of asphalt shingle. When I had mine installed, I couldn’t believe how light those things are.
2 - Looks like tile, if you get that style. Without the extreme weight of concrete tile, which can’t be put on a house that wasn’t designed to bear the load. They can be made in a variety of other appearances as well.
3 - Very fireproof. One of the best choices if you are in a fire area.
4 - The manufacturers claim they add lateral stability to the roof, which, coupled with the light weight makes them better in earthquakes.
They have some disadvantages, too. You have to walk on them the right way to avoid denting them. If somebody’s going to go up on your roof, make sure they know what they’re doing (step BETWEEN the “tiles”). They probably aren’t as wind resistant, although they are adequate if properly installed. I’d think twice in hurricane country.
