Alternative Roofs

Hi

I'd like it if we could talk about other types of alternative roofing, other than living roofs. Living roofs are NOT suitable to a large part of the world, including mine.  What I would like to talk about are ceramic tile roofs.

There are more than one type of ceramic tile roofs. Most people in the US think of the Medeterraininan style of curved tiles. But I would like to find info on the flat roof tiles used in areas of Northern France--type of clay used, installation, roofing bracing/trussing to support the weight (tile roofs are pretty heavy in comparison to most modern roofing materials). And can anyone tell me if a ceramic tile roof like this can be used as part of a rain cachement system?

Why ceramic tile? I'm a ceramic artist, I live in a state where earthernware clay is plentiful, and where a living roof would curl up and die, then become a fire hazard.

Leigh

I am actually most familiar with the California style of tejas. And of course, there are also some amazing styles from Asia.

I think a ceramic roof is probably the best sort of roof for a rain collection system.  As long as none of your glazes are particularly toxic, it will work great.

It sounds like ceramic is perfect for you, but I suspect that purslane or a similar plant (spreading succulent) might work as a green roof in most hot, dry climates.

ceramic seems like a great alternative. around here it would probably succumb to hailstorms though. somewhere I thought I read that there needs to be extra reinforcement of the structure to support the increased weight load.

I'm in Oklahoma too.

Succulants wont work hetre, because we do get rain, in buckets, but only at certain times of the year--spring being the main rainy season, with fall a secondary rainy season. They would drown out. The problem in the rest of the year, when you get no precep at all from the end of May until mid-September. Lots of humidity but no rain. As well as high winds, and grass fires.

Sure, you use food-safe glazes on the tiles, same as if you'er making functional pottery.

Hail could be a problem, breaking tiles, but hail is a problem with just about any kind of roofing material. If your using highfire tiles, rather than earthernware, they might hold up better. I'm thinking about the mideaval church in Northern France that has a ceramic flat tile roof that is over 300 years old, surely that has been through more than a few severe storms, besides all the wars.

This piece of crap is screwing up and not working right. Every time I type a letter in, it bounces around so I dont know if its working or not.

Okay, lets try this again. Apparently, the program doesn't want to post very many lines per post. &%@#* if I know why.

Okay, yeah, the roof would need extra bracing, thats one of the things its vertually impossible to find out about. Anything to do with ceramic tile roofs, period, is impossible to learn about. Its like the alternative building community has a real blind spot where roofs are concerned. The only acceptable roof is a living roof, and I for one think that is a really short-sighted attitude. Concidering that there are numerous types of ceramic tile roofs around the world, in vernaculare archetecture, we really need to take a more serious look at this kind of roofing.
Leigh

bdswagger, please take a look at this thread:  https://permies.com/permaculture-forums/2199_0/tinkering-with-this-site/problems-typing-stuff-in

Its Great to have an artist thinking about this. You could have all sorts of fun designing new types of roofing tile.

Where I grew up all the houses used red clay "pantile". This tile has a S-shaped cross section, in effect each tile curls up over its neighbor to shelter the joint from weather. I am sure there are lots of alternative shapes that would still function. Have you thought about making different shaped tiles that could work together on the same structure?? you could get all sorts of new textures designed into the roof. Umm...this has got me thinking.

You might have something well worth patenting.

The main thing to think about, as far as the structure goes, is weight. A tile roof is far more heavier than the asphalt shingle you see in USA. Not only does the roof timbers have to be stronger, the walls also have to withstand the extra compression *and* the force tending to push the walls outwards.

Hence you find houses in the UK will have tile roofs and brick or stone walls. Stick built can still be found, but only for chickens! really!

I noticed in Japan that tile was used a lot, but they quite often used a glaze as well. Often a dark blue. Don't really know why. Some of the older structures were very impressive. Massive pole barn type of construction with curving, overhanging rooves.

Keep us informed on your progress....and give us some pictures!

Thomas

tc20852 wrote:
Not only does the roof timbers have to be stronger, the walls also have to withstand the extra compression *and* the force tending to push the walls outwards.

Have you ever seen Gaudí's model of the Sagrada Familia?  It's an amazing case of art as engineering.

The model is upside down, built of thin cords and bags of shot.  The bags of shot are filled to proportionally represent the weights of the various structural members and sheathing materials, and since the cords all follow lines of tension, the angles in the model naturally tend to those that keep all members of the finished building in compression.

It's the sort of thing a computer model would be used for today, but I really like the elegance of the old-fashioned way.



http://en.wikipedia.org/wiki/Antoni_Gaud%C3%AD#Artistic_style

I have so many questions tangential to this, but will save them.

however, a few notions:

tiles are typically appropriate for two specific applications  which each result from  a combination of two conditionsnes

ha: high temperature flux+ aridisols (a soil type);

or ww: wet+ wind (monsoons, hurricanes, etc.).

where these ha conditions exist the tiles perform the following functions:
temperature moderation: clay tiles will typically be unglazed, and therefore breathable/absorbent. They are often oriented behind shading facades to facilitate their heat dissipation. heat rises; the head of this rise creates a vaccum pull, and  available air rises to fill it. drawing this from a dry well source or basement (where the shaded deep ground-cooled air is), or even a wet cistern or well, as in the work of hassan fathey,  the building draws cool air up by heat transfer/ through the tiles. MAssive adobe walls moderate temperature not only on solar days but annualized- a tangent, but part of the equation if we consider the spanish mission style in dry central american climates where thier imported architecture was largely appropriate for their new climate. massive adobe means more draftable cool air...

the ww style is often glazed specifically as it is designed to shed water more than provide 'air conditioning'. it is also, in some ways a sign of wealth; typical of monsoon tropics, roofs were circumglobally palm, or thatches, for many cultures, and considering the technology, quite reasonable. a thatched roof might blow off in a severe storm, but youd be in a better shelter when it happened since its a STORM! once the storm is over it takes just a few days to repair, vs. other ther options which, as hurricane Katrina showed, take more than a couple of days. is an dinvestment in materials and time issue. only in the last millenia has wealth and industry conspired to give us the glazed tile in profusion. and its handy, it shed water from monsoons well and has the weight to withstand some wind. in pictures of japan and china you can see where people put boards with rocks tied as weights over tehir roofs to add weight during the windy seasons...anyone whos seen 2" of  rain blow  sideways  in under 1 hour can understand why such tiles are super nice to have.

the stump
ok, so when those technologies  get transported elsewhere, they need to exhibit functions that cannot be produced with lower investment return ration, time, enviro impact, $, etc., back off the stump

allright, that all spouted, check these cats out. i dream of being able to see Egypt and fathy's work one day.

http://en.wikipedia.org/wiki/Hassan_Fathy

from there look around. I hope you are as inspired- or more so- than Ive been by his work.

theres more there than tiles, to be sure 

Having been a student of ceramics, I also find a ceramic roof very appealing.  Living in New York State, slate roofs are very common and they must need a similar hefty support system.  Perhaps that could give you some leads.  There is this company in Vermont - http://www.evergreenslate.com/ ;
This site has some very informative videos embedded - one about clay roofs - http://www.claytileroof.com/
And this is an interesting page about the history of slate roofs - http://www.nps.gov/history/hps/tps/briefs/brief29.htm

Does this suit the original poster?

http://en.wikipedia.org/wiki/Lustron_house

The enameled house, huh?  Very interesting.  Too bad they demolished them.  What a waste.  Typical.
I have just been reading this - http://www.larkbooks.com/catalog?isbn=9781579905323
It is a great book - "Building Green" - that covers building a complete small house start to finish.  I highly recommend it.  I'm enjoying it, anyway. 

lavenderdawn wrote:
The enameled house, huh?  Very interesting.  Too bad they demolished them.  What a waste.  Typical.
I have just been reading this - http://www.larkbooks.com/catalog?isbn=9781579905323
It is a great book - "Building Green" - that covers building a complete small house start to finish.  I highly recommend it.  I'm enjoying it, anyway.   

I know of one of those Lustron houses here and we have old gas stations that appear to be made the same way.

The Iranian architect Nader Khalili developed a whole ceramic house years ago.  It was built out of bricks entirely, with vaulted ceilings/roofs, then sealed up and the whole house was fired.  He seems to be doing eartbag building these days, but it did make an incredibly durable house.  Or school.  Whatever.  I used to have a copy of his book Racing Alone.  Fascinating reading.  The whole point of the ceramic house was to make a strong, durable house that poor people could afford, both here and in in his native Iran.  Google Nader Khalili Ceramic Houses and look around.  His houses did not need additional tile on the roof...

Take care,

Lauren Neher

Don't forget about tile

Oak and cedar might also be good options for you.

Mr. Kalili-who recently passed away, I believe-did do a book on what he called 'geltaftan', or 'fired earth'. I have the second edition, and its very good. "Ceramic Houses and how to build them" or something close to that. I'm being lazy or I'll check the title. The problem with this form of building, is that you need a skilled person to lay the bricks for the roof.

I think there is a group in Texas doing this kind of building-WITHOUT firing, as regular adobe-and they have a website. I'll look back through my bookmarks and try to fing their site to post here. Hopefully thats not one of the ones I lost.

Leigh

Newbie to the website (oldie to perma, DYI, self-suff'y), guessing this factoid might fit here (sorry if redundant - just scratching the surface of this goldmine -

Per this quote from Paul at Richsoil re: wofati - ..'if polyethelene could be replaced with....racking my brain...' --  See pg 14 of Planting Green Roofs and Living Walls, N Dunnet et al - "Diagram of traditional Scandanavian turf roof with sections of birch bark forming a waterproof layer."

iran been fireing houses since the ziggurats where built. Mr. K did no new work for his book just put it in modern lingo. nice guy but to much the fame hog, i do miss him.

Ok so you got a nice tile roof all sitting round on the ground made french style by Mick's under vaquero supervision.  tiles produced are a bit thick but they will keep the rain off. course you need to build the roof support  as a cruck and use up half the forest.

french tiles where modeled on welsh slates; near as i can tell. IE. the tile size in many old houses is the hand cut limit of 12" X 24" X 1/4"  (might get a little thinner but not by much) this is pretty neat cause it is also about the limit you can get to fire correctly.

back to the tile makers; south america, much of the med and aisa  use thick un glazed tiles, china uses thick glazed tiles in all but the hot parts. heres why ( from sever sources) unglazed tiles are thermal mass and to cool a building, the tiles are almost always dew damp in the morning and hold that water till late in the day when it is hottest the evaporation keeps the house cooler.  by contrast many chinese tiles are glazed where you need the water to run off the roof and snow to slide off during the melt but stay on in mid winter.

back to the structure the french tiles where found to be lighter than slate so the supporting structure could be a bit less substantial this then translates to being able to build bigger roofs with larger spans for less material costs over all.
so to answer your question in part the type of tile roof would depend on where you are and what you need the most. if you need summer cooling and winter insulation then unglazed thick terra-cotta tiles are a shoe in. however if you need to run the rain off in a hurry and need a bit of mass to soak up some heat so your house will be cool at night you might want to look at thick glazed tile. if you want to make a span and have a cook fire going, minimal snow load and no real need for heat retention then a french tile or a welsh slate might just be for you.

hope i helped a little

bdswagger wrote:I'd like it if we could talk about other types of alternative roofing, other than living roofs. Living roofs are NOT suitable to a large part of the world, including mine.  What I would like to talk about are ceramic tile roofs.

Two other ways that I've made roofs are:

1) tiled stone - we have a lot of large flat slabs of granite from the local quarries. These are called skins. They are left over from removing the rough portion off the outside of quarried stone blocks. They measure up to 16' x 6' x 8". One of these alone is sufficient to make a roof of a shed and they can be tiled on a tilt to cover larger areas. Sometimes I've buried them to create an earth sheltered space, sometimes to make a bridge over a stream, etc.

2) ferro-cement barrel vaults - we built wooden form work, add steel and then put a thin layer of cement over it. This is how we did our tiny cottage http://flashweb.com/home/cottage and here's another example dog house http://flashweb.com/blog/2007/09/dog-house-bottles-roof.html The dog house was a model of what we were doing for the cottage - a place to test ideas.

Both can be buried or left exposed. In the winter everything is buried - with snow.

Cheers,

-Walter
Sugar Mtn Farm
in Vermont

Here in Ibiza,  and the other Balearic Islands the traditional style houses are cubist with flat roofs. In the old days the roofs were made from timber with a mortar of sand, lime and ash. Not suitable for much traffic. Nowadays the flat roofs are built like the pic below.
This pic is just a floor but it's the same construction as a roof. The gaps between the blocks and beams will be filled with concrete, a waterproof membrane on top of that, poured reinforced concrete and then tiled.



The roofs are tiled with a flat non glazed clay tile of about 10cm x 20cm. The roof is then very often used as a sun terrace.

It's not very "alternative" but maybe it will give you some idea of just how strong a tiled roof needs to be?

Whats wrong with steel?  Cheap, easy to install yourself, recyclable, good for rain water collection and lasts a really long time.

ferrocement or laminated ferrocement will last for centuries or longer.  They can be built for about the same cost as a metal roof, but will outlive it by a factor of 10 or more.  I've seen several huge earth working machines (backhoes, bulldozers, etc) drive on top of these roofs.  They are quite literally bomb-proof.  Nothing competes with that sort of strength for the same cost.

Earthen roofs, like Nubian vaults and domes are also long lived, very cheap to construct, and are beautiful.

One problem I have with metal roofs is the noise, especially when it rains hard.  I also like my buildings to outlive me. $0 years is not an acceptable lifespan to me.

Earthbag domes seem to be fairly straightforward, and I imagine you could substitute bricks for the same structure.

Timbrel vaults and domes interested me for quite some time, but finding quality tiles was difficult and expensive.

For me, the perfect roof would be panels made from ferrocement that could be assembled by a team of 3-4 people.  This method is used in India and China, and I think it would work here, too.

just ran across this:
http://www.instructables.com/id/Make-Shingles-and-Siding-Out-of-Aluminum-Cans-Bee/
The poster has no idea how long it may last, but if aluminum cans are used they should last a long time.... aside from wind weakening the hold down system.

velacreations wrote:
ferrocement or laminated ferrocement will last for centuries or longer.  They can be built for about the same cost as a metal roof, but will outlive it by a factor of 10 or more.  I've seen several huge earth working machines (backhoes, bulldozers, etc) drive on top of these roofs.  They are quite literally bomb-proof.  Nothing competes with that sort of strength for the same cost.

Earthen roofs, like Nubian vaults and domes are also long lived, very cheap to construct, and are beautiful.

One problem I have with metal roofs is the noise, especially when it rains hard.  I also like my buildings to outlive me. $0 years is not an acceptable lifespan to me.

Earthbag domes seem to be fairly straightforward, and I imagine you could substitute bricks for the same structure.

Timbrel vaults and domes interested me for quite some time, but finding quality tiles was difficult and expensive.

For me, the perfect roof would be panels made from ferrocement that could be assembled by a team of 3-4 people.  This method is used in India and China, and I think it would work here, too.

So you think a steel roof is going to be needed to be replaced in your lifetime?  Perhaps painted but replaced, I doubt it.  Lets say it did though, I don't know where you are getting these cost figures from but steel is cheap, like really really really cheap.  I think I've seen it for sale at local hardware stores for something like a couple bucks maybe or less for a full sheet, I think they are like 4x8.

I don't plan on driving a backhoe over my house so that's not really a relevant issue to me or anyone else I know.  Foam under the panels should take care of the noise and having a thick walls/roof will assure it wont be an issue.

Also, I've never really seen any kind of commercial product or anything remotely close to a ferrocement panel for a roofing product.  Seems like a needless issue to fix, steel is cheap, readily available, easy to work with/install/repair, proven, and did I mention its cheap?

Brian wrote:
So you think a steel roof is going to be needed to be replaced in your lifetime?  Perhaps painted but replaced, I doubt it.  Lets say it did though, I don't know where you are getting these cost figures from but steel is cheap, like really really really cheap.  I think I've seen it for sale at local hardware stores for something like a couple bucks maybe or less for a full sheet, I think they are like 4x8.

I don't plan on driving a backhoe over my house so that's not really a relevant issue to me or anyone else I know.  Foam under the panels should take care of the noise and having a thick walls/roof will assure it wont be an issue.

Also, I've never really seen any kind of commercial product or anything remotely close to a ferrocement panel for a roofing product.   Seems like a needless issue to fix, steel is cheap, readily available, easy to work with/install/repair, proven, and did I mention its cheap?

Brian, you might want to go to the hardware store and price the metal roofing -- I don't think it's as cheap anymore as the last time you looked at it.  Last time I checked it was pretty expensive, as a matter of fact -- can't remember exact prices because it's been probably six or eight months ago, but it was way more than a couple of dollars a sheet.  You might get that price for used roof metal, but that would have holes in it that would need to be patched (doable, but time-consuming).  I personally like metal roofing (even the noise it makes in a hard rain!), but it isn't cheap.

Kathleen

I just bought some galvanized steel roofing:
$24.07 for 10' long x 38" (nominal 36" after overlap)

I have some that is about 40 years old. Rusty but still working fine. Might be 60 years old.

I have other areas that are 20 years old which I put on that look almost like new.

I also have some aluminum roofing that is 50(?) years old or so that looks perfect.

Be sure to put on with enough appropriate gasket screws of the right metal type.

This is in the north east (Vermont) where we get bathed in acid rain from the mid-west.

My understanding is that copper roofs last for hundreds of years. That is what rich places like Dartmouth College use. I plan to use copper in some spots for this longevity. It is pretty too.

Cheers

-Walter
Sugar Mountain Farm
Pastured Pigs, Sheep & Kids
in the mountains of Vermont
Read about our on-farm butcher shop project:
http://SugarMtnFarm.com/butchershop
http://SugarMtnFarm.com/csa

Kathleen Sanderson wrote:
Brian, you might want to go to the hardware store and price the metal roofing -- I don't think it's as cheap anymore as the last time you looked at it.  Last time I checked it was pretty expensive, as a matter of fact -- can't remember exact prices because it's been probably six or eight months ago, but it was way more than a couple of dollars a sheet.  You might get that price for used roof metal, but that would have holes in it that would need to be patched (doable, but time-consuming).  I personally like metal roofing (even the noise it makes in a hard rain!), but it isn't cheap.

Kathleen

You know what I was wrong, the price I was thinking of was $1 a sq ft with screws and not per sheet, which is still really cheap, considering it's as easy as operating a cordless impact(screw gun) and that's about it.  You would also need some mastic but it's not expensive at all.  So figure a 1000 sq ft roof would run you about 1100/1200 bucks if you did it yourself? 

If you ask me, a dollar a sq ft for something thats going to last probably the rest of your life and is extremely easy to install and fast - I just don't see why you would want to use anything else other than visual appeal.

I've built many ferrocement roofs for under a $1 square foot.  I built a 250 square foot cabin with ferrocement for $600 total, including windows, doors, wall, floor, roof, everything.  And they are literally bomb, tornado, hurricane, termite, and fireproof.

$1 a square foot for metal roofing doesn't include the support structure underneath... ie purlins, rafters, etc.  You're looking at least $2-3/sf for everything and installation.  $2-3/sf for something you have to replace in 10-50 years is a waste of money, when you have a better options that are cheaper and stronger.

A $1/sf ferrocement roof is finished, done, nothing more needed. I installed a 500 sf ferrocement roof in 3 hours with 4 people working with me. Total cost was less than $600, including labor. None of those people had done FC before that day.  Our only tools were a concrete mixer, wheel barrow, bucket, and a few trowels. Nice and quick.  It'll last 400 years or more.

I have seen a lot of professionally installed, code approved metal roofs blow off in high winds or start leaking within 5-10 years of installation.  Yes, you will need to replace a metal roof within your lifetime (as many of my neighbors have found out the hard way).

The failure point for metal roofing is the attachment to the support structure.  In many cases, folks use wood purlins and rafters.  After a few years, with the metal expanding and contracting, the screw points begin to leak.  Water starts rotting out your support structure, and before you know it, the roof collapses or a strong wind lifts up the metal.  I have seen it at least a dozen times within 10 miles of my house.

I don't skimp on durability, especially when it is cheaper!  A Nubian vault will have a lifespan of at least 500 years, and it could be done for less than $1/sf, easy. DIY ferrocement is less than $1/sf.

Ferrocement is completely DIY friendly. FC panels can be made at home, or made for a community. They are all over India and China, and there is nothing preventing them from being used in the states.

If you live in low wind areas, no hurricanes, no tornadoes, no fires, no termites, and somewhere where trees can't fall on your house, then by all means, go with a metal roof.  If you want assurance that your roof will outlive your great great great great great great grandchildren, then go with an Earthen roof: Nubian Vault, Timbrel Vault, Block dome/vault, Ferrocement, Laminated Ferrocement, acrylic concrete, and many others.

velacreations wrote:
I've built many ferrocement roofs for under a $1 square foot.  I built a 250 square foot cabin with ferrocement for $600 total, including windows, doors, wall, floor, roof, everything.  And they are literally bomb, tornado, hurricane, termite, and fireproof.

$1 a square foot for metal roofing doesn't include the support structure underneath... ie purlins, rafters, etc.  You're looking at least $2-3/sf for everything and installation.  $2-3/sf for something you have to replace in 10-50 years is a waste of money, when you have a better options that are cheaper and stronger.

A $1/sf ferrocement roof is finished, done, nothing more needed. I installed a 500 sf ferrocement roof in 3 hours with 4 people working with me. Total cost was less than $600, including labor. None of those people had done FC before that day.  Our only tools were a concrete mixer, wheel barrow, bucket, and a few trowels. Nice and quick.  It'll last 400 years or more.

I have seen a lot of professionally installed, code approved metal roofs blow off in high winds or start leaking within 5-10 years of installation.  Yes, you will need to replace a metal roof within your lifetime (as many of my neighbors have found out the hard way).

The failure point for metal roofing is the attachment to the support structure.  In many cases, folks use wood purlins and rafters.  After a few years, with the metal expanding and contracting, the screw points begin to leak.  Water starts rotting out your support structure, and before you know it, the roof collapses or a strong wind lifts up the metal.  I have seen it at least a dozen times within 10 miles of my house.

I don't skimp on durability, especially when it is cheaper!  A Nubian vault will have a lifespan of at least 500 years, and it could be done for less than $1/sf, easy. DIY ferrocement is less than $1/sf.

Ferrocement is completely DIY friendly. FC panels can be made at home, or made for a community. They are all over India and China, and there is nothing preventing them from being used in the states.

If you live in low wind areas, no hurricanes, no tornadoes, no fires, no termites, and somewhere where trees can't fall on your house, then by all means, go with a metal roof.  If you want assurance that your roof will outlive your great great great great great great grandchildren, then go with an Earthen roof: Nubian Vault, Timbrel Vault, Block dome/vault, Ferrocement, Laminated Ferrocement, acrylic concrete, and many others.

You are throwing around a lot of numbers without specifics such as these buildings cost XYZ amount but who knows how good they are at insulating and how thick you need to be and how much that adds to the cost and what kind of labor costs are associated with a construction method of this sort, I've never even heard of building a home out of it, and if it can pass code. 

Lots of variables, with that said, I'm not sure why you think you would need to replace a home in 10-50 years.  Even homes that are typical stick frame construction last longer than that quite often and newer methods using SIPs or other various materials are easily going to last that long while having extremely high R values associated with them, and are easy to assemble and can pass code.

You say a $1/sf ferrocement 500 sf roof completely finished cost you less than $600.  Well I'm not a mathematician but that's more than $1/sf, so...?

Saying you have seen something fail isn't really a convincing argument, all sorts of things fail all the time that are not done correctly.

You say that you have seen dozens of failures within a 10 mile radius of your home for metal roofs, I think maybe the person installing them did it incorrectly because to put it in very simple terms if metal roofs failed as often as you would like us to think, people simply would not use them.  Apparently pubwvj has all three of the finest metal roofs on the planet.

I'm not quite sure what kind of home you are going to put ferrocement panels on top of, stick frame?  Sounds kinda heavy especially with snow/ice and how are you going to use panels that dont let anything through the seams, more cement or something - what happens if/when you have to replace one?  So yeah you probably wont put them on stick frame so whats left?  Probably thinking well obviously you just build the whole house out of ferrocement!  Well like I said, lots and lots of variables that aren't being put into account but just a gut feeling here if ferrocement was the fantastic building material you claim it to be I think it would be more well known.  What you are essentially describing as far as I can tell is basically an ICF home with no I or F.


Your last line about no fires/tornadoes/hurricanes/termites/trees is a non sequitur.  People live in those exact areas with metal roofs and they do just fine and have for many many years and will continue to do so.

So in short I'm skeptical about most of your claims.

I've never even heard of building a home out of it

Lots of homes use ferrocement components, and especially in India and China.

Even homes that are typical stick frame construction last longer than that quite often and newer methods using SIPs or other various materials are easily going to last that long while having extremely high R values associated with them, and are easy to assemble and can pass code.

What are the oldest stick frame buildings around you?  Around me, the oldest is 50 years, and it is in terrible shape.  I know of many earthern/cement style homes around me that are measured in centuries, not decades. I am sure some stick frames might make it to the 2 century mark, and good for them.  Most won't, though.

We'll see if SIPs last a long time.  The fact of the matter is we don't know until they do.  All sorts of variables cause homes to fail in real life.  I'm not really willing to take a gamble on it.

You say a $1/sf ferrocement 500 sf roof completely finished cost you less than $600.  Well I'm not a mathematician but that's more than $1/sf, so...?

That's materials AND labor was $600.  It was a bit cheaper, actually, but I also include my time.  If we were to count materials only (fair comparison to the above posts), it was actually a bit under $1/sf

You say that you have seen dozens of failures within a 10 mile radius of your home for metal roofs, I think maybe the person installing them did it incorrectly because to put it in very simple terms if metal roofs failed as often as you would like us to think, people simply would not use them.  Apparently pubwvj has all three of the finest metal roofs on the planet.

Actually, the majority of folks around me don't use metals roofs, mainly because the ones that do don't last very long. pubwvj is in a more forgiving climate, I believe.  Our climate doesn't tolerate weak materials....

I'm not quite sure what kind of home you are going to put ferrocement panels on top of, stick frame?

No, I don't build stick frame buildings, I like durable construction.  I want something that can last centuries.

what happens if/when you have to replace one?

Concrete is super easy to repair.  Just chip it out, paint on some acrylic bonder, and apply new cement.

You could definitely build an entire house out of FC, I have done it.  But, for walls, I prefer thick earthen materials like adobe, CEBs, earthbags, cob, etc.

Just because a home is made with FC doesn't mean it lacks insulation.  Every FC roof I have built has R-30 or better.  But the insulation part is the same, whether it is metal or FC, so I don't really see the need to discuss it.

if ferrocement was the fantastic building material you claim it to be I think it would be more well known

That's the same line of reasoning Big Ag uses when talking about organic/natural farming techniques. It is well known in many areas where durability and cost are the important factors.

The fact of the matter is that the majority of the world lives in earthen buildings, and metal roofing is a very small minority.  Even in the developed world, it is by no means the most popular roofing system.  As far as durability is concerned, how many 200 year old metal roofs have you ever seen?  Now, how many 1000 year + concrete or earthern material roofs do you know of?

How many metal roofs do you know that have survived a tree falling on them?  Tornado? Hurricane?  Very few.

So in short I'm skeptical about most of your claims.

That's fine.  I don't need to convince you, but I thought I would offer my years of advice.  I'm not selling anything here, just telling you what I have come across with these systems.

You say that you have seen dozens of failures within a 10 mile radius of your home for metal roofs, I think maybe the person installing them did it incorrectly because to put it in very simple terms if metal roofs failed as often as you would like us to think, people simply would not use them.  Apparently pubwvj has all three of the finest metal roofs on the planet.

In our area we have a lot of metal roofed homes. Perhaps the majority of homes are metal roofed. Standing seamed is preferred but also corrugated sheet metal. Houses around here run back to about 200 years. We're up in the mountains so lots of high winds. I use gasketted screws meant for roofing.

I'm curious as to how you make the ferrocemment water proof?

You insulate with polystyrene or fiberglass just like in regular construction?

No one yet has mentioned it, so I am feeling a need to throw in here that concrete buildings were what killed a large majority of the Haitians in that last earthquake.  I am not in an quake prone area but we do get some tremblers, and I would be uneasy living under a concrete roof.

Houses around here run back to about 200 years.

There are metal roofs that old?  Or just the houses?

I'm curious as to how you make the ferrocemment water proof?

We try and mix the concrete as dry as possible, and vibrate well to get a good base, and then coat with an acrylic concrete sealer.

We insulate with EPS sheets.

No one yet has mentioned it, so I am feeling a need to throw in here that concrete buildings were what killed a large majority of the Haitians in that last earthquake.  I am not in an quake prone area but we do get some tremblers, and I would be uneasy living under a concrete roof.

Those were flat sheet, poorly engineered, poorly constructed roofs.  Properly constructed ferrocement, especially in vault and domes, and extremely earthquake resistant.

Haiti had galvanized metal roofs fall on people, as well.  It wasn't the material, it was the way it was installed.

velacreations wrote:There are metal roofs that old?

Yes. Especially at Dartmouth College - even older examples. I use that as an example because it is close to us so I've seen it a lot. They like metal roofs and are a good place to look at. Standing seam is the most common in our area. Lots of very old barns and houses done with it. Later came the corrugated metal which lasts for decades or even a human lifetime.

Valerie  Dawnstar wrote:No one yet has mentioned it, so I am feeling a need to throw in here that concrete buildings were what killed a large majority of the Haitians in that last earthquake.  I am not in an quake prone area but we do get some tremblers, and I would be uneasy living under a concrete roof.

1. We don't live in an earthquake prone area. We get the occasional stress releasing small ones but not the lethal ones.

2. I designed and build our house for earthquake resistance including a floating pad foundation with loose key locks to the mountain ledge.

3. Ferro cement is earthquake _proof_. The problem in Haiti, and other places with this same issue, is the lack of reinforcing steel and method of construction. The construction they did had no resilience to motion and simply fell apart. Ferro-cement has large amounts of fiber and steel in it. (I use both for different issues.)

4. Our house is tiny so it would vibrate. ~20'x14'

5. Our house is a single story. Tall structures have a lot more trouble than short squat ones.

Stick construction fares better than mere mortared block construction in an earthquake but core poured, steel & fiber reinforced concrete and ferro cement is far better. Had they built properly in Haiti, and other earthquake prone areas, they would not have had nearly as many deaths. Perhaps almost none. It isn't a matter of expense. Knowledge is key.

ronie wrote:I'm curious as to how you make the ferrocemment water proof?

There are admixes that help and I have made truly waterproof basins and things but even with that I cap with a waterproof membrane.

ronie wrote:You insulate with polystyrene or fiberglass just like in regular construction?

Not fiberglass. I use poly, lightweight concrete and foil-bubble-bubble-foil. See:

http://flashweb.com/blog/2007/09/float-my-concrete-boat.html

and more at:

http://google.com/search?q=site:flashweb.com+cottage%20OR%20%22dog%20house%22%20roof

Cheers

-Walter
Sugar Mountain Farm
Pastured Pigs, Sheep & Kids
in the mountains of Vermont
Read about our on-farm butcher shop project:
http://SugarMtnFarm.com/butchershop
http://SugarMtnFarm.com/csa

velacreations wrote:ferrocement or laminated ferrocement will last for centuries or longer. 

The mortar will, but I'm not so sure that reinforcement, so close to the surface, can survive that long.

Reinforced concrete hasn't been in use for as long as concrete, but we have a pretty good idea of the rate of corrosion vs. the distance from the weather to the metal. There are lots of ways to improve performance in this regard. Coatings on the reinforcement are a popular option: the new bay bridge, for example, seems to have all of its re-bar dipped in vinyl.

The distance isn't straightforward to compute, either: pores don't count as separating anything. In undergrad, my department was housed in a building (Evans Hall, UC Berkeley) where the designer had specified a much greater than usual distance from the surface to the re-bar; the contractor thought that was nonsense, and built it the normal way. Unfortunately, the concrete mix was experimental, with pumice aggregate. The reinforcement corroded over the course of a decade or two, the rust was larger than the steel had been, and the expansion due to corrosion spalled off chunks of the building. So when I went in for classes, there were plywood shields overhead to keep falling pumice from braining us students, and many of the windows were boarded up. It wasn't a beautiful design to begin with, but after they repaired the damage, they applied a thick coat of paint in garish colors, which reminded me of lipstick on a gargoyle.

My department was housed in a beautiful building that Hearst had commissioned to honor his father's success in mining, at all times other than the time I was a student there. They did an amazing seismic retrofit job while I was a student, building a steel frame under it and replacing the foundation with shock absorbers that can handle a meter of movement...I just wish they could've done it a year earlier, or a year later.

Joel Hollingsworth wrote:The mortar will, but I'm not so sure that reinforcement, so close to the surface, can survive that long. Reinforced concrete hasn't been in use for as long as concrete, but we have a pretty good idea of the rate of corrosion vs. the distance from the weather to the metal.

There are ferro cement boats over 100 years old that are doing great. Seems to do well even in the ocean (salts). Here are some interesting sites to read for those interested in ferrocement.

http://www.ferroboats.com/
http://en.wikipedia.org/wiki/Ferrocement

Additionally the ferrocement can be the base form and then thicker cement can make up the bulk of the roof. This is how I have done it. The 1/2" thick layer of ferrocement is the bottom layer. After that hardens up I was able to use that as my mold to thicken the roof - very strong and solid at that point. The additional concrete then becomes a self supporting arch.

bdswagger McCoy wrote: Living roofs are NOT suitable to a large part of the world, including mine.

That's a pretty big blanket statement.I have a pretty clear understanding of most roofing systems employed across the globe and can't think of any environments where a roof covered with earthen materials could not work. Here in coastal B.C. they eliminate the rot and corrosion problems that other systems encounter, in a high desert situation they moderate diurnal temperature swings, in the tropics they work as year round evaporative coolers while preventing rot.

I've just poured through a multitude of other different environmental scenarios and compared to the vernacular roofing systems found in those areas, the living roof wins according to my criteria of what makes a good roof. I don't have any visual bias in this regard and wouldn't consider watering the roof in most cases, so in some ultra dry situations it might be simply the membrane covered in a gravelly mix to absorb the sun's rays. In other areas, extremely resilient species could populate it and in more lush environments it would be necessary to control rampant growth of deep rooted plants that want to puncture the membrane. If there's a corner of the world where for some reason an earthen roof could not serve better than most materials currently in common use, I'd like to know about it.