Brian Hatfield

I'd also say that it burns the wood more completely.  When you have a wood stove you have a lot of ash left over and smoke.

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.

Silver wrote:
The April edition of The Journal of Light Construction had an article on Super Insulated Slab Foundations that was a decent read. http://www.jlconline.com/cgi-bin/jlconline.storefront/4c3e60a401e31d5c27180a32100a05e1/Product/View/1004sup
You can find the author's web site here http://gologichomes.com

I'd love to read it but they want me to subscribe(see: pay), and I'm not doing that to read one article.

speedfunk wrote:
Those tiers are a really good idea.  We are in the middle of our passive solar home now.  With out knowing your location look into what the location offers as far as passive approaches.  Ours had a natural spring so we built the house below it...aimed it south , bermed etc.  Maybe a nook from a previaling wind? Maybe orient house long ways towards south?

One caution that I do not hear enough people bring up is air exchanges.  Those air tight homes will become sick homes in time.  You need fresh air.  If you have high medical bills that will wipe out any heating savings fast.

Since we are all about being as passive as possible we have used earthtubes other options include heat recovery air exchange units.  The heat recovery units cost a bit ($1,500?)  to install and then they need to maintained, they also use electric.  We are hoping convection will power the earthtubes.   You might want to check out John Haits book, Passive Annual Heat Storage.
good luck in your venture it's an awesome goal!. 

You know I have been thinking about HRVs for a while, and I'm not quite sold on the idea just yet, I'd like to see some data on how effective they are or aren't. 

After all weren't they invented on the premise that homes like these are so tight that you are going to get sick because of all the germs in them etc and not because they are so tight people were getting sick so someone invented them?

Anyone have any definitive data on this?

Silver wrote:
Hi Brian
Glad to hear you want to build an efficient home. Don't start with "SIP", even if you choose that technology in the end.
I'm in the middle of reading Heating, Cooling, Lighting by Norbert Lechner http://www.amazon.com/Heating-Cooling-Lighting-Sustainable-Architects/dp/0470048093. Probably the best resource I've seen in one place.
One of the first points Lechner makes is that buildings should be designed with three tiers
Tier 1: Basic Building Design (Heat retention, Heat rejection, Heat Avoidance)
Tier 2: Passive Systems (Natural Energies)
Tier 3: Mechanical Equipment (Heating & cooling equipment, renewable energy, lighting equipment)

"Right design choices in tier one can reduce the energy consumption of buildings as much as 60 percent. The second tier involves the use of natural energies through such methods as passive heating, cooling, and daylighting systems. The proper decisions at this point can reduce the energy consumption another 20 percent. Thus, the strategies in tiers one and two, which are both purely architectural can reduce the energy consumption of buildings up to 80 percent. Tier three consists of designing the mechanical equipment to be as efficient as possible. That effort could reduce energy consumption another 8 percent. Thus, only 12 percent as much energy as needed in a conventional building."

Your SIP idea fits into tier 1, but you should look at the other options available too.

Another good book, but somewhat less practical slightly less up to date is http://www.amazon.com/Passive-Solar-Primer-Sustainable-Architecture/dp/0764330705 a reprint of his 1970's book, which is very likely in your library system somewhere.
At a minimum, do a bit of reading before you build. Make it a house worth building and living in for generations.

Sorry I took so long to respond to this post, not sure why I didn't get an email telling me someone replied but anyway, I didn't mean to imply that the only thing I was looking into was simply using SIPs and that was it.  I had already planned on using a slab for a thermal mass and using over hangs on the windows and facing the home to the south with small or no windows on the other walls.  I thought about using a GSHP but I think the systems designed today are far too large, expensive, require too much electricity for a home that small and I think going with a mini split ductless system is the best way to go.  I realize in the winter/colder months their efficiency goes way down so I thought maybe using a removable housing to insulate it during the colder/winter months and putting it where the sunlight can hit it(and painting it black of course) to warm up the removable housing to increase efficiency.  If all else fails I could just get a propane back up, build a rocket mass stove, or perhaps install some sort of evacuated tube solar thermal radiant floor system.  I planned on collecting water anyway so why not just use that water in the ground cistern as a place to dump excess heat etc.

Anywho as you can tell I have put some thought behind this and wasn't just looking at one area to solve all the issues of energy production/consumption during home ownership.

Mostly what I was getting at was I think SIPs are the best material you can use to get your home to net zero if you were going to try that, by best I mean commercially available, customizable, very high R value, easy to assemble and readily available, and proven.  So what I would like to know is if other people have come to this conclusion and what results are they getting to see if what I think produces real world results and doesn't just sound good on paper.  So far it looks that way.

Erica Wisner wrote:
Never wrap a rocket mass heater barrel in insulation - it needs to be actively cooling the exhaust gas for the draft to work properly.

Wrapping it in a thin layer of masonry, tile, or cob can work OK, as long as it can still radiate to shed excess heat.

-Erica Wisner
http://www.ErnieAndErica.info

Well, if you had the barrel wrapped in some insulation and surrounded with a copper tube with cold water flowing through it constantly, then it would be actively cooling it, one might argue even better than the surrounding air.

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.

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?

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

Well I think I found the solution to the problem, and that solution is a mini split ductless air sourced heat pump, bit of a mouthful eh?  Seems to be what many people use in Japan, is very small and very efficient and some of them perform fairly well in the winter months even.  It does draw quite a bit of power during the colder months because it become less efficient as it gets colder outside.

So I had an idea - why not build a box around the outside condenser unit that is half white and half black and when the seasons change from hot to cold you switch the direction of the color of the box to face the sun, obviously black in the winter and white in the summer?  Build the box out of sip panels, shouldn't cost much money for a tiny box like that.

Maybe no box in the summer months and maybe just a completely black box in the winter to raise the starting point of the condenser unit outside?

Thoughts?