glass bottles/jars as roofing?

A terra cotta roof has the half round like things that make up the roof. 

I'm living in community and see lots of bottles and jars going into the recycling. 

And we are exploring building greenhouses and other shelters and talking about harvesting a cedar tree to make shakes.

I have never tried to cut glass ...  suppose a standard size beer bottle could be cut ... eliminating the top and bottom ... the cut vertically into three equal sized pieces ...

I suppose there could be thousands of little hooks that could hold up the glass.  Each piece of glass laying a quarter of an inch over the piece below. 

A whole roof could be made of nothing but glass and the bits of wire to hold the glass up.

I suppose it would be freakishly heavy.  And it would not keep out the cold air - so there would need to be another roofing layer. 

But a glass roof should last a really long time. 

Just something that popped into my head.

All I know about terra cotta roofs is that they are very heavy and need extra support.

I have read about a way to 'cut' bottles, but have not tried it. 
They say to tie a cotton or sisal string (must be organic) tightly  around the place where you want the cut, like just above the bottom, and trim off any excess string past the knot.  Then soak the string with lighter fluid and light it, and then just as it starts to burn out, immediately immerse in a bucket of cold water.

DO NOT use gasoline.  DO NOT do this indoors.  You may want to hold the bottle using an insulated oven mitt or pot holder, etc.

I don't know if this method would work for the vertical cuts, but it might.

Sand all cut edges using a sanding block or a power tool and goggles and gloves.

For something like you were contemplating, I would use the full length of the bottle, as there would have to be a certain amount of overlap.  You might as well cover as much area as you can. 

I wonder if the glass would act as a sort of solar collector?

Sue

I like the way you are thinking.

Perhaps a tile saw could cut them.
I saw that on an earthship video with Michael Reynolds.

In Greece they make roofs out of cement and catch all of the water.

See photo.


Each house is a rain catchment because there is no fresh water on the island.
Done that way for centuries.

A lot of beams are required to hold up the roof.
They use 2"x8" beams on 2 foot centers.

My folks have glazed cement tiles on their roof, they are heavy, they provide insulation, but as heavy as they are the wind still blows one off once in a while.

They seem to like them.

I saw a good video about cutting bottles using a lighter after the cut & then placing it under cold running water.

Never heard of glass roofing... Not sure you'd want anything heavy falling on there... I once saw a drawing that showed a victorian era animal shelter that had been constructed with some kind of cement floor. The builders had placed empty glass bottles in the floor before placing the cement thereby providng insulating air pockets for a warmer floor.

On the subject of roofs, I recently read of an idea that all roofs (new construction or replacement/reno) should be of the cold (vented) type with a reflective surface. The theory goes that this would create a higher global albedo thereby reducing temperature increases - especially in areas of dense construction - since a larger fraction of solar energy would be reflected back into space...

Cool roof for a cooler world?
http://www.energybulletin.net/node/53534

A glass cutting video was posted somewhere.  I poked around youtube and found it.
Take a look.
The technique would give you uniform pieces to work with.

I strongly suspect that it would be easier and safer to remelt the bottles and make roofing tiles out of them.

Might be a problem in areas which get frequent hail..sometimes the hail here will do a lot of damage.  How easy would this be to fix? OTOH  glass bottles are likely a lot tougher  than normal window glass.

Another question  might be about  if the rounded bits of glass might act as a sort of solar prisms and get really really hot. If not, and you were just looking for a roof, and weren't really concerned with trying to capture the light, you could perhaps bed them in something like papercrete which would help a lot with the insulation questions.  I think I would want to try this somewhere away from anything flammable before I did a whole roof with it though.

You could maybe do a roof the same way they do walls, with the whole bottles embedded in something (?)with the necks down to stop them falling out. If only the bottoms were in the sun then the question of maybe setting fire to your building shouldn't come up. Repair might still be a hassle though.

Emerson White wrote:
I strongly suspect that it would be easier and safer to remelt the bottles and make roofing tiles out of them.

I've heard it is very difficult to work with bottle glass, and can even require special equipment, because the mix is optimized for cheap production by machine rather than easy working by hand.

This might belong in the energy forum instead, but here's a roof made from bottles:

Green bottle roof-mounted water heater

Old topic but I agree with whoever said melt 'em. You would have very little waste that way and you could recycle that. Cutting them you'd have ...maybe half waste in the neck, bottoms and broken ones.
ETA: If you melt the crushed glass into a large (1 foot?) Leggo-type form, you could make walls with them too. The ones for the roof would need a lip on one long edge to shed rainwater. If you ever want to move, re-stack the leggos on pallets and haul....

There's an idea.  How easy or difficult is it to melt discarded bottles and form them in molds or shingles?  Rocket stove glass shop?

I suppose a kiln of sorts could be built with 2 chambers. One would be for the "melting" of the glass and the other for annealing, since un-annealed it would crack. The forming into shape would have to be done, then put the "bricks" back into the annealing oven for a while.

Is there anything that the lousy bottle glass could be doped with to make it easier to work? Maybe a few old broken windows?

Again, if you want to blow recycled bottle glass, you either have to be exceptionally talented, or add in some new raw materials to make the mix more usable.

I think a wood-fired kiln would compound this difficulty. That effort might be better spent obtaining a better glass feedstock.

I'd suggest crushing the glass and sintering it, rather than trying to work it qua glass. Structural blocks could be sintered from very coarsely-crushed bottles, and I think glass processed in a ball mill (maybe with additives) could make for a decent ceramic glaze.

My only experience with sintered glass is in glassware as a filter, it leaks water just like  a sieve . It there anything that could be done to make it waterproof for a tile? Also is the only way to form glass the blowing process? I'm envisioning glass being poured out onto a hot mold, either flat or gently curved, then having two nail holes formed into it while still hot.

Emerson White wrote:
My only experience with sintered glass is in glassware as a filter, it leaks water just like  a sieve . It there anything that could be done to make it waterproof for a tile?

Frit can be filled in with any number of different things, but actually it takes some care (properly sift the powder, stop sintering early enough) to keep an open, porous network like you're accustomed to. If you use a variety of particle sizes, and sinter long enough, it will sinter to the point of closed pores.

Emerson White wrote:Also is the only way to form glass the blowing process? I'm envisioning glass being poured out onto a hot mold, either flat or gently curved, then having two nail holes formed into it while still hot.

I was using "blowing" as a shorthand for all the varieties of hot work, including the ones you describe. I don't know all the details, but I think bottle glass would have to go in and out of the furnace several times for what you describe, even if work was done very quickly, and a lot of the tiles would shatter while hot due to unexpected delays.

I think it would be safer, by far, to cut bottles using a scribe and 90 C water (i.e., not the flame method described earlier in this thread), and drill any needed holes with a masonry bit. Scraps and errors could spend a while in a rock tumbler, then go to a pottery shop.

Actually, its the bottom of glass bottles that act as a magnifying glass-so possibly it would  be the bottom that could cause fire due to refracted light?

And while beer/wine/whiskey bottles are thicker and harder-tempered glass-they will still break if hit by descent sized hail. I think the glass panels in greenhouse roofs anymore, are safety glass-which is a glass containing plastic, I think? Alot harder to break.

Leigh

Pam wrote:
Might be a problem in areas which get frequent hail..sometimes the hail here will do a lot of damage.  How easy would this be to fix? OTOH  glass bottles are likely a lot tougher  than normal window glass.

Another question  might be about  if the rounded bits of glass might act as a sort of solar prisms and get really really hot. If not, and you were just looking for a roof, and weren't really concerned with trying to capture the light, you could perhaps bed them in something like papercrete which would help a lot with the insulation questions.  I think I would want to try this somewhere away from anything flammable before I did a whole roof with it though.

You could maybe do a roof the same way they do walls, with the whole bottles embedded in something (?)with the necks down to stop them falling out. If only the bottoms were in the sun then the question of maybe setting fire to your building shouldn't come up. Repair might still be a hassle though.

Some safety glass is "tempered," heat-treated to have internal stresses that counteract usual modes of breakage. Other stuff has plastic. In the case of cars, the former is used for side & rear windows, the latter for windshields.

Speaking of which, I think the curved sections from car windshields/rear windows could be overlapped in the style of tejas, if you had access to a large junkyard. Supporting them would be a challenge...

Ken, thank you for the youtube clip. I had some other projects that I was thinking about and that bottle cutting method looks great. I will definitely give it a try.

I wonder if the bottle necks would make good electric fence insulators.  Hang the mouth of the bottle on a nail and wrap wire around the neck.

The bottoms could be taped together and used as building blocks. 

I tried doing this with beer bottles and wine bottles one year in an attempt to make "punt glasses" (the indentation on the bottom of the wine bottle is known as a punt).  After cutting they're supposed to be about as tall as a pint glass.

Anyways, cutting the bottles is not terribly difficult using the scoring > heat > cold water method.  HOWEVER, it is very difficult to get the bottles to cut on a straight line like you might find on a factory made drinking glass.  If that isn't essential to your project then it's not so bad, however if you intend to have the open end of the bottle sticking out where a finger could touch it, this project would become very labor intensive very quickly since you'll have to sand the edges for quite a long time for them to be safe.  A machine might help speed the process, but I was using a Dremel tool without much luck, and I think anything more powerful than that would risk breaking the glass. 

If there is a potential way to use them without involving any cutting, I think you'd have a much more viable project on your hands. 

Also, melting them down into cinder block sizes would make for a cool effect in a non-load-bearing wall, or for a shower wall, room divider, etc.  You could separate them by color and then mix each color of brick together in a nice pattern.

And to weigh in on the roof aspect, IMHO using these in a roofing situation wouldn't be a very good idea.  Without knowing how to temper the glass (which I personally don't know how to do) these types of glass would definitely not hold up for long.

Mangudai wrote:
I wonder if the bottle necks would make good electric fence insulators.  Hang the mouth of the bottle on a nail and wrap wire around the neck.

The bottoms could be taped together and used as building blocks. 

Yes, bottle necks make great insulators.

Where I grew up we had "wind the handle to ring the operator" type telephones (i.e. with no dial) until 1992.
Often the lines were single wire, earth-return.
I remember a particularly remote phone line that would have been there until 1992 that was strung from tree to tree along the roadside. The insulators were broken off beer bottles pushed over a cut-off branch on each tree.

Whatever you are doing I would first make an attempt on a VERY small scale.
Roofs must withstand heavy winds and the wind actually can lift up roofs. Snow weighs heavily etc. You must not only think on the tiles/glass or whatever but what is in between. Old houses  with very  simple tiles where first double tiled and second the roof space had only minor  use.
An important consideration is the heat dilatation in summer a roof might get +70°C and in winter -25°C the materials used must have the possibility do expand and contract (and a lot). And you don't want your glass tiles to fall on your head...
And I can agree with the fire danger.

You might really be better off using the glass for garden projects, floors etc.

Paul,

This guy made a video about the various ways to cut bottles. He has a method that works really great. Check it out - Joe

bad idea,
the glass is much more fragile than terracotta tiles, and it would be immensely labor intensive to cut the thousands it would require for this purpose...then there are the necks, you would break more than you could cut successfully.
However...
Glass bottles work well as units in masonry, you can use them on side, like ends exposed, as a "masonry unit" stacked row by row with mortar. This allows much light and because the strongest part of the bottle is by design, the bottom, it is relatively strong.
P.s. making shakes is a learned skill, you'd be better off getting left over cedar shingles from job-sites- or better use tar paper.

Now that glass has been panned.... how about tin cans? They are also half round and if you used the big ones, they would be the right size (quart size I think) take both ends off and cut the rest in half.... they could be riveted together (one U and one n) with one nail in the U to hold it down. Lap each row as normal starting from the bottom. Try to find cans that are painted on the outside,,, most are coated inside these days. Or paint each row as it is mounted... or paint the whole thing once mounted, but you will miss under the over lap.

Would you even have to cut the bottles?
I couldn't find a link for the show i saw.
It was about an Island town with a lot of poor dock workers.  The workers would unload round rocks from ships and load Brandy . Long story short they took all the ships Ballast (rocks) and built walls and roofs from them. Slanted roofs that are still standing today.

for bottles you could  get a hot fire going, and flatten them, and while you are at it poke a hole for nailing in each.

the same for cans, it would be much better to flatten the cans whole, nail them like like shingles, and paint- or better pine pitch, or the like.

Not bottles but a glass roof with heat scavenginging capabilities.

www.trendhunter.com/trends/glass-roof-tiles

Robert Ray wrote:
Not bottles but a glass roof with heat scavenginging capabilities.

www.trendhunter.com/trends/glass-roof-tiles

Unfortunately what we are seeing there is the neo-"green" exotics- complex, expensive- and made to emulate traditional materials.

Rural studio has done some of this, but you won't likely find it on their website

Probably a lot of unanswered questions here, are the tiles being made or could they be made of recycled glass?
Would the 350kw of heat energy be a determining factor.
  Life span?
Emulating traditional materials with new is not necesarily a bad thing.

See http://www.glassartists.org/Img64640__Img64640_Flat_Bottles_004.jpg.asp

unless you had a large heat source and a crew, this would be very labor/time intensive,
My vote is for flattened tin cans, nailed overlapping- untreated,

Questions re: flattened tin cans:

1. After cutting off both ends (the circular parts), would you just flatten the can in on itself, forming a double layer as it were; or would you slice open one side and flatten it out into one long section?

2. After cutting off the ends, wold you need to worry about the can rusting?  Should you dip it in enamel or Rustoleum (c) paint or some such before actually nailing it to the structure?  Would either  the rust or paint adversely affect any rainwater collection efforts?

I would not cut the bottom end off- it will still crush flat,and then you will have more material- and no, I would not cut it open,
This is simple, take the can, which has one end missing, and crush it flat (on the side), you can use a rock, or a truck, or make a press. One nail it all it should take to fasten it down.
Rust? I would not worry about, if you are, I would dip them all in urine to flash rust any parts which are exposed? most of the can is treated in some way or another, and if you ever find them in the woods, it takes a can a very long time to rust out- I would not treat them in any way.
The plus of less steps here is less labor and less risk of cutting yourself.

as for rain-water, rust is organic, paint chemicals are not-

Well, here's another question:  Since tin cans usually have contained organic matter and may have paper labels, AND given that a rocket stove can get to be close to 600 degrees F pretty easily, would there be any advantage to putting the cans in the output of a rocket stove for a few minutes until all the organic material has been burned off?

You would have to watch it pretty carefully or in short order you might have nothing recognizable as "can"

hillbillyarchitect wrote:
as for rain-water, rust is organic, paint chemicals are not-

I thought that organic meant derived from living things?

Rust is a chemical reaction involving oxidation/reduction.