Bobby makes excellent points.
Even if your cardboard only blocks do not support flame, they may slowly smolder for a very long time inside a wall without anyone noticing. If/when enough papercrete turns to ash, the entire structure and roof system could be compromised and collapse.
However, all need not be lost.
As Donald pointed out. Standard stick framed structures are vulnerable to fire and burn down all the time. It is very possible that his cardboard blocks are safer than standard framing due to a slower combustion rate. IF PEOPLE ARE AWARE THAT THE PAPERCRETE IS BURNING. The biggest concern might be when someone smells a hint of smoke for a week and can't find the fire until after half the structure wants to collapse on them.
Bobby also very accurately points out that Donald's structure is his own, and he is more than entitled to build it as he sees fit. I wholeheartedly endorse that sentiment. Especially if the structure being built only puts at risk the guy who is building it.
Assuming someone wants to build using blocks that are combustible. I encourage some slight alterations in the typical techniques used to lay up the blocks in the wall.
I encourage manufacturing an appropriate number of "fire stopping" blocks that can be laid in the wall in such a way as to prevent any fires from spreading throughout the entire structure.
Just as standard stick framed construction requires fire blocking to prevent stud cavities from becoming chimneys that spread fire quickly. A limited number of strategically placed "fire stopping" blocks might serve a similar function in a papercrete wall.
If one were to lay up blocks in a wall with a non combustible row ever few feet, fire would not be able to spread vertically beyond that fire stop. If columns of non combustible blocks were also laid in the wall ever few feet, horizontal spreading of smoldering fires could also be stopped.
I can also imagine that using a non combustible plaster inside and out would also be extremely useful.
Using a non combustible layer of plaster, even if it is a non combustible papercrete plaster could be used in all utility cutouts for wiring and ventilation. I suspect that other than from a wood stove, the easiest way to start a papercrete wall smoldering might be via an electrical malfunction. If all those wiring pathways were coated with a non combustible layer, you could probably prevent any sparks from igniting the papercrete in the first place. Even better would be to use electrical conduit as well as a non combustible plaster layer inside the channels cutout for wiring runs.
Another technique would be to use a non-combustible papercrete mortar to lay up the combustible blocks. That would tend to isolate each block individually helping to prevent the spread of a smoldering fire from one block to the next.
In my opinion it is simpler and better to build entirely out of a non-smoldering papercrete. I would like to see this be considered standard "best practice" for building with papercrete. The small additional costs are justified for the added value and peace of mind.
However, if someone is determined to do otherwise, I do think that if someone takes appropriate precautions and takes advantage of the above suggestions it is possible to build papercrete structures using some portion of combustible paperctete that are at least safer than standard "code approved" structures. How well someone pays attention to the details would be important for success.
--- In papercreters@yahoogroups.com, "liberty1_27606" <liberty1@...> wrote:
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> Donald,
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> Your project is your own, to do as you please. But --- there is a real problem with combustibility. Even though a block may only smoulder slowly, eventually it will become all ash, with no structural strength. And it will set the one next to it on fire. And the next. Then your whole wall has no strength. No big conflagration with dramatic flames, but the building collapses. If I remember right,even back then, Gordon was concerned.
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> I would suggest you do fire tests on some sample blocks. And leave it overnight in a safe place. The next day, if there is a small area of ash, that's OK. But if the whole block is ash, it needs some help,
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> I believe there are inexpensive borax or boric acid sources. And it only takes a small percentage. A month or so ago there was a discussion about borax.
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> <http://en.wikipedia.org/wiki/Borax>
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> <http://en.wikipedia.org/wiki/Boric_acid>
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> (For those using clay or cement; in sufficient quantities, they also retard fire.)
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> Bobby
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