Papercreters: [papercreters] Re: PC and rebar

I think a pc dome would be difficult to seal completely especially in an area where you live where you get a lot of rain. I would think the only way to be completely confident on the mold issue would be to infill between conventional framing and siding but then one loses the "cheap" factor which is one of pc's strong points.

--- In papercreters@yahoogroups.com, Jerry Fant <jerryfant@...> wrote:
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> I am not as much worried about total failure as much as the flexing will create cracks in the outer finish. These cracks will let moisture into the pc. I live in Central Texas, the Hill Country and we get a good amount of rain about 35 inches a year sometimes! Black mold is prevalent here. My walls that I am designing are flat walls, a conventional style structure to match my house and such. If I were building a dome type structure the issue would not be as important since the curvature of the house and roof would alleviate most of the mentioned stress'. So why not build a dome structure? I am not a fan of the dome, in the floorspace inside the dome I see a lot of wasted space especially for a workshop.
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> Jerry
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> --- On Fri, 6/12/09, donald1miller <donald1miller@...> wrote:
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> From: donald1miller <donald1miller@...>
> Subject: [papercreters] Re: PC and rebar
> To: papercreters@yahoogroups.com
> Date: Friday, June 12, 2009, 4:58 AM
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> I am definitely not an engineer or architect,just someone who is 65 years old and has spent a good portion of those years involved in carpentry and building of some sort or another. I belonged to the Carpenter's Union for 10 years although most of that time I was working on dams and the work I did was not related in any way to house construction. In the ensuing years I have done a lot of building and built a 2000 sq. ft. house for myself in 1981 which was approved by the county building and planning department. It seems that we are excessively concerned about a wall collapsing or a roof blowing off a building which in my recollections down through the years is a very rare occurrance short of a full blown hurricane or tornado. And in the case of hurricanes, the biggest damage is from flying debris and water and of course a tornado is totally off the charts and not really something the average person can comprehend as far as the destructive factors
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> I am not advocating using a papercrete beam to attach trusses or rafter to but having a wood bond attached to rebar anchored in concrete. There are of course multiple forces attacking buildings and structures of all kinds. I would guess wind would put the most stress on structures and again I think it is very rare that a roof blows off a building short of a major hurricane or tornado. And if one were to fasten the trusses and or rafters with hurricane brackets the probability of that happening would be greatly minimized. As far as stucco and plaster cracking, that is hardly life threatening and if one were to look at tract housing you would find that that is a very common occurence and not a huge problem except for asthetics.
> I read in Gordon Solberg's Building with Paper Crete and Paper Adobe book where a so called building engineer stated that for every entry in the building code book there had been a person killed by substandard building practices, thus neccessitating the rigorous codes that we have. I would challenge anyone to substantiate that statement as I can truthfully say that I have never heard of or read of or talked to anyone who has experienced such occurances. A ceiling will crack or bow and a wall might bow and a floor might flex, but as far as this being life threatening and a great worry, I find this to be greatly overblown and a means to validate the building and planning departments overblown budgets. It would seem that we are overly concerned with the "safety" of alternative building methods, ie, straw bale, cob, papercrete to the point of stifling the utilization of these alternative building methods. Anyone with a reasonable amount of experience with
> building can build a building using these alternative methods that will stand up to the elements and not be a threat to himself, family or neighbors. After all, the human race and our American forebears have survived and flourished using common sense and a pooling of knowledge and experience to provide the neccessities of life long before we had the bureaucratic structure we have in place today to tell us how things need to be done.
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> - In papercreters@ yahoogroups. com, "slurryguy" <slurryguy@ ..> wrote:
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> > Donald:
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> > I agree with a lot of your points, but I disagree with a few of your conclusions.
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> > The strength of any building material is always important. While snow loads can be significant. Most every climate and every geographic location has its own issues to deal with. Every building should be designed to withstand whatever forces it encounters. Hopefully any building is adequately strong that nobody has to "worry" about it, but that's a pointless semantic argument, hehe. Regardless of the wording. I think we always should be aware of what various materials are good at.
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> > A beam on top of a wall serves several purposes.
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> > 1. It distributes all loads above the beam evenly throughout the wall. This is important because almost every house design has at least some uneven loads above a wall. There are the obvious, like an air conditioner mounted in the attic, or a partial 2nd floor. There are the more obscure, like wind loads being stronger on the upwind areas and weaker in the downwind areas. There are many possibilites. In any case, it is best to spread those loads out. This is especially true with papercrete. Papercrete can often flex a little. A large point load on top of a wall may tend to sink into a papercrete beam and create an uneven area everywhere above. This could easily cause trusses to break, and roofs to leak. In fact, if one part of a papercrete wall carries more load than another part of a papercrete wall, it could easily lead to cracking stucco and plaster (if stucco and plaster are the surface treatments. By spreading the loads out over an entire wall,
> everything reacts in unison. Keep in mind that roof trusses and roof rafters can be considered a bunch of individual point loads. Some roofing materials can actually be heavier than many snow loads. Concrete roofing tile may be the heaviest. Those beautiful ceramic roofing tiles that are popular in the Southwest and in Mexico aren't exactly lightweight either. Don't get me started about the constant fluctuatons that come from wind loads.
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> > 2. A beam on the top of a wall also acts as a wall stiffener. This acts to prevent a wall from bowing inward or outward. Again, this is another common cause of plaster and stucco cracking. It's typically not vertical loads that cause wall bowing, it's horizontal ones. You would be surprised how many tons of lateral pressure a very unassuming wall may need to resist.
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> > 3. The beam also acts as a strong attachment point for whatever structural members are above it. Roof trusses being the most obvious.
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> > 4. When built properly, the beam on top of the wall is directly tied down to the foundation. We shouldn't be counting on the tensile strength of the papercrete wall to hold things down. This concept has been discussed previously on Papercreters. I even got out my crayons to draw a rather ugly looking picture describing one method of attaching a wall beam to a foundation. (There certainly are other methods that what I described.) Here is one thread where we discussed it:
> > http://groups. yahoo.com/ group/papercrete rs/message/ 2581
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> > If you scroll down to the bottom of that page, you will see the responses people posted to that message.
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> > When considering everything that a beam is asked to do. My personal opinion is that a papercrete beam simply isn't up to the challenge in practially every situation I can think of (at least in any structure of any size). There are better materials to perform as a beam. They need not be particularly expensive either.
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> > --- In papercreters@ yahoogroups. com, "donald1miller" <donald1miller@ > wrote:
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> > > I'm reading this discussion on tensile-compression strength with interest. It would seem that we don't have to worry too much about the compressability of a papercrete wall unless one lives in an area that gets a tremendous snow load and such an area might not be a good choice for pc except as infill and well protected from external elements as most areas that get a lot of snow also get a lot of rain in the spring and fall. The other force to deal with is the lift force. A conventionl framed 2X4 wall with a double top plate is not inherently strong but it combats the lift forces because it is anchored to the concrete footing. If a pc wall has rebar anchored in concrete say every 4 feet or so and with a bolt welded to the top of the rebar to attatch to a plate thus compressing the wall somewhat, it will not require a humongous plate to attatch the roof to as it will be anchored securely to the concrete.
> > > As for making a beam out of pc and when thorougly dry placing it on two blocks and standing in the center, that is not how a beam would be stressed on top of a wall. There would be a wall under the entire beam so it wouldn't break in the center as it would in the experiment. As for lift on the roof, I live in La Paz County Arizona [The Arizona Outback] and I am not too worried about snow loads and excessive rain. I deal with very severe winds and short, extreme rains in the summer. Most of the storms don't have much rain, only a lot of dust. I am going to do a tradional southwest adobe type structure with no roof overhang and canales to run off what water will fall on the roof.
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