The $5 per square foot house is fire, storm and earthquake safe. It pays the occupants to live in itself via reduced maintenance and can become a work of art.

http://www.ferrocement.com/Shelter-2010/post-1_5-2010.html

It's good to see you on here, Garret. I have been a big fan of your resources for a long time.

I built a ferrocement house for $2/sf, btw.

This might be considered hijacking, but I'm wondering if you have done any more experiments with acrylic concretes? I did a roof a few years back, and I think I've optimized it a bit to do it better. I hope to do another roof later this year to test out the new system. When I was researching it, your resources were a great inspiration to me.

Wow! $2 per square foot. Great work! How about posting a how to on ferrocement.com for people to learn from.

PS > I posted my experiments open source exactly for someone like you. Improvements and evolution of the techniques and materials is the goal of open source.

PSS > I put up a new picture from India today, need to set up another three presentations. Here's the photo http://www.ferrocement.com

well, actually, you have a much better manual than me up there. I did the old-school FC with rebar + lathing in a barrel vault design (kinda like in your book). I happen to live in a country with cheap steel and cement. Sand is free locally.

Also, that price doesn't include windows, doors and finishing, just the structure. I've built a few FC roofs for $1/sf, pretty easy to do, really.

The main point here is we are arriving at similar figures for the same portions of a structure. In science this is referred to as a verifiable experiment completed.

The cheapest value per sq ft. that I have ever obtained was $9 per sq. ft. when I added 1100 sq ft. to a house that was up 9 ft. on blocks. We built another story beneath the existing roof. All labour was paid. Most materials were salvaged from demolitions. My older brother did most of the work for $20 per hour which was a good deal cheaper than if I had hired most carpenters. It had 2x10 walls insulated to R 32, 2 bathrooms, 2 bedrooms and a small rental suite. The backhoe guy recieved 1200 bricks for his trouble.

Today the same thing would cost me $25 per sq. ft. My brother charges more, I don't have a glut of perfect wood and insulation, drywall and stucco cost a bit more and Steve the backhoe guy has finished work on his place and would need to see money instead.

Are you guys all related? Seems like a Connelly family reunion.

Connally and Connelly are not related.

In my experience, wood framed buildings are considerably more expensive than FC.

A lot of the cost of a structure is in the roof. In my area, a metal roof runs about $2-3/sf plus labor, whereas a FC roof runs around $1/sf plus labor. Acrylic concrete runs about $2/sf, and has about the same amount of labor as metal, though FC is more labor intensive.

I've seen several owner-built earthen homes (earthbags, adobe, cob, CEB) built for around $5/sf, depending on the roof system.

Well, I gotta say I like the sound of Connally being like Connelly but I do have a little difference in cost experience.

Before accounting details ,,, I understand Connolly is a catholic branch, not sure but assume Connally might root in protestant. Connelly is rumored to be the non religious ones who didn't want to fight over religion but can get their dander up over freedom from the English. This is all hear say.

Permitted ferrocement houses in my California experience are about 15 - 20% premium on wood framing. This premium could be reduced with foundation savings because the structure is itself like a girder but there are no sane engineers that will fight city hall about foundations.

My $5 figure is for bamboo framing, a thin burlap acrylic and cement roof and floor, and labor supplied free by people who need homes. It is a shell that includes windows, doors, rain gutters a little bit of electrical conduit and plumbing for future use and a nice finish.

PS > The big difference in ferrocement houses is they are storm, earthquake and fire safe,. They don't need as much insurance and maintenance and thus eventually pay for themselves with this savings.

Questions regarding FC - what additive is in the mix to make it waterproof? And is this then leached into the surrounding soil, or is it held in the mix?

I really like the idea of FC roofing, but I'm still concerned about the chemical makeup.

Thanks for the links!

Ferrocement roofs are best waterproofed with a mixture of acrylic and cement. Nothing leaches out of the cement into the soil that I know of. Cement is old sea shell rock formations ground and baked to drive water from the stone molecules. The usual environmental concern is energy used to make cement. This way it is thin and reduces pressure on forest harvest. http://www.ferrocement.com then go to the first to items on the list for more info.

flyash can also be added to help with that, but the absolute best thing for waterproof concrete is the least amount of water possible in the mix, then vibrate it very well when applying. Vibration does more for waterproofing that just about anything I've seen.