Cellulose is problematic by its role in the environment. Termites and fungus love the stuffl and in pure form it is not very stable. I suppose you could 'chemically' treat or enclose it, but why bother with something like epoxy when you can better use the epoxy with glass or carbon fiber, which are more inert?
Actually, other than its affinity for water papercrete is a nearly perfect material; with enough PC in the mix to make it mechanically stable it won't burn, and termites won't eat it. The problem is that, unlike straw bales, the paper fibres are close enough together for water surface tension to span them, so that the entire air space within the block will fill with water through capillary action. That doesn't happen to straw. The sealing problem arises because, while you can coat the fibres with for example latex (the cheapest and most effective solution I found was the water-based version of DryLok) it doesn't seem possible to shield the ENDS of the fibres, particularly where they emerge at the edges of the structure.
Yes, you could paint the whole thing (rather expensively) with epoxy, but if your armor has even one tiny flaw anywhere the entire block will saturate, and then you will never get it dry because it can't evaporate through your moisture barrier. This is mainly a problem because dry papercrete weighs about 20 lb/cuft, but soaked papercrete weighs closer to 80 lb/cuft, and papercrete structures have failed under the unplanned load from so much weight gain.
Just to clarify, PC is abbreviating Portland cement?
So I'm thinking straw bales coated with papercrete, and painted with latex.
Re: big bad wolf, I heard that straw bale structures have better wind resistance than other options, the bales are just so big and heavy, and and are strapped down.
So the bale is the main structural element. The papercrete doesn't like water, but the straw will absorb what doesn't dry out of it when it sets, just as with the plaster or stucco used to coat straw bale structures now. The paint on the outside prevent further moisture from entering, just have to repaint occasionally. Maybe even put gypsum or plaster of paris powder between the bales during construction, perhaps future water would be absorbed?
Prof_B: Yes, I took to abbreviating Portland Cement PC in my notes.
Papercrete over straw bales would be a definite possibility. The most important thing would be to avoid creating a capillary pathway between either the ground or the outer papercrete shell and the interior.
I did come up with a formula that can be sprayed which is a dead ringer, once applied, for sheetrock, including its fire resistance. Before I abandoned the project I was planning to use that formula for the interior, a thin ferrocement shell with galvanized wire reinforcement for the outside, and polyurethane foam in between. Unfortunately the housing market collapsed while I was in the market for a piece of land on which to site my experiments and final structure.
How big would the foam be, and the cost? I think foam would be great for insulation, and easy to handle, but would they be TOO light for an external structure?
Bales are cheap (a farmer said some folk pay to have them hauled away) but are very heavy.
If BOTH were used, would it be best to put the foam on the inside or the outside? Or is this an either / or situation?
So in a wall with multiple insulation types it would be on the same side as the vapor barrier is normally done in your climate.
I live in a cold climate, we mostly heat our houses, so we put the vapor barrier on the inside.
In generally hot climates, mostly air conditioned, it would be on the outside.
What we are attempting to do is prevent warm humid air passing through the wall and condensing in cooler layers.
We can't completely eliminate the humidity migration but we want to mitigate the effects.
All insulation and vapor barrier types have a vapor penetration rating. Always have the tightest on the hot side and lessor on the colder side.
In this case, Plastic first, foam second and straw third.
Note! The house wraps like Tyvec, are not considered to be a vapor barrier. It freely passes vapor.
I like the style of straw bale building where the bales fill in the walls between wooden roof support beams. The alternative is to sit the roof directly on the bales, which seems a bit too flimsy to me.
6 inch by 6 inch columns will take quite a bit of load. I see what appears to be a good slab on grade foundation under it all. Without the columns, the straw is going to compact and settle in rather unpredictable ways.
I don't see any diagonal bracing for lateral loading such as wind loads. Having steel tension cables provide lateral loading would be a big plus.
The straw is basically insulation which is a huge issue in the Far North. It really doesn't have much structural strength and will shift and settle with age. But it is excellent cheap insulation, especially if treated with fire retardant and some sort of pest control.
The standard stud wall construction was created to provide a very simple system that provided for both vertical and lateral loading. Once you learned the structural requirements it was easy to build and very easy for building inspectors to verify the structure was safe. Post and beam is requires a bit more care to avoid a sudden failure. One rotten post footing can have a great deal of impact.
Regarding vapor barrier....
Wood rots with moisture. I'd exclude the moisture with the vapor barrier on the exterior. At least that was commonly accepted in rainy Oregon. Humidity on the interior of a home can be controlled by keeping the home below about 28 degrees centigrade. The amount of water in the air is much less below that.
Termites love fungus, and fungus loves dark humid places. So exclude the dark humid places. That means putting a vapor barrier on the ground in the crawl space too and NO plumbing leaks.
I've repaired an awful lot of termite and dry rot damage and I am not sure that Duane's approach would prevent such in all cases. Humidity as a cause of rot has a lot to do with dew point changes. Wood homes that are rot free anticipate where moisture causes problems and try to keep the wood dry. Simply, dry wood doesn't rot and wood under water does not rot - it is an alternation of wet and dry that takes its toll.
Vapor barrier and modern windows do tend to make extremely tight houses and these can create modern problems of how humidity is handled - such as condensation on the interior of windows running down and rotting sills below windows. When a door is opened to the warm humid outside, wet air rushes in and the cooling seems to happen on the glass first. This has nothing to do with vapor barriers, but humidity gets in and converts to run off on cold surfaces. I have used tile window sills instead of wood on the interior to sucessfully prevent rot. Cold humidity is not as much a problem and usually resolved by a well constructed and well sealed exterior. Bathrooms and kitchens rot sooner as water and steam from bathing and cooking are present, also poorly vented laundries.
All this is certainly NOT a 20 hour robot built home. But the point is that good building design is very much about details being properly executed and these things add to the cost and labor.
Many traditional homes have done quite well with a good coat of paint being the only moisture barrier. But these days we have dramtically increased insulation. I can't imaginge why one should bother with Tyvex or any other building paper if it did not at least provide a moisture barrier. One often sees that by holding back moisture, it also stops migration of termites and dry rot to the underlying structure.
Not sure what the difference betwen vapor barrier and moisure barrier really is or if it is worth noting. This is not like Goretex rain coats. The wood must stay reasonably dry to not deteriorate.
Comments
Actually, other than its affinity for water papercrete is a nearly perfect material; with enough PC in the mix to make it mechanically stable it won't burn, and termites won't eat it. The problem is that, unlike straw bales, the paper fibres are close enough together for water surface tension to span them, so that the entire air space within the block will fill with water through capillary action. That doesn't happen to straw. The sealing problem arises because, while you can coat the fibres with for example latex (the cheapest and most effective solution I found was the water-based version of DryLok) it doesn't seem possible to shield the ENDS of the fibres, particularly where they emerge at the edges of the structure.
Yes, you could paint the whole thing (rather expensively) with epoxy, but if your armor has even one tiny flaw anywhere the entire block will saturate, and then you will never get it dry because it can't evaporate through your moisture barrier. This is mainly a problem because dry papercrete weighs about 20 lb/cuft, but soaked papercrete weighs closer to 80 lb/cuft, and papercrete structures have failed under the unplanned load from so much weight gain.
So I'm thinking straw bales coated with papercrete, and painted with latex.
Re: big bad wolf, I heard that straw bale structures have better wind resistance than other options, the bales are just so big and heavy, and and are strapped down.
So the bale is the main structural element. The papercrete doesn't like water, but the straw will absorb what doesn't dry out of it when it sets, just as with the plaster or stucco used to coat straw bale structures now. The paint on the outside prevent further moisture from entering, just have to repaint occasionally. Maybe even put gypsum or plaster of paris powder between the bales during construction, perhaps future water would be absorbed?
Possible?
Papercrete over straw bales would be a definite possibility. The most important thing would be to avoid creating a capillary pathway between either the ground or the outer papercrete shell and the interior.
I did come up with a formula that can be sprayed which is a dead ringer, once applied, for sheetrock, including its fire resistance. Before I abandoned the project I was planning to use that formula for the interior, a thin ferrocement shell with galvanized wire reinforcement for the outside, and polyurethane foam in between. Unfortunately the housing market collapsed while I was in the market for a piece of land on which to site my experiments and final structure.
Bales are cheap (a farmer said some folk pay to have them hauled away) but are very heavy.
If BOTH were used, would it be best to put the foam on the inside or the outside? Or is this an either / or situation?
So in a wall with multiple insulation types it would be on the same side as the vapor barrier is normally done in your climate.
I live in a cold climate, we mostly heat our houses, so we put the vapor barrier on the inside.
In generally hot climates, mostly air conditioned, it would be on the outside.
What we are attempting to do is prevent warm humid air passing through the wall and condensing in cooler layers.
We can't completely eliminate the humidity migration but we want to mitigate the effects.
All insulation and vapor barrier types have a vapor penetration rating. Always have the tightest on the hot side and lessor on the colder side.
In this case, Plastic first, foam second and straw third.
Note! The house wraps like Tyvec, are not considered to be a vapor barrier. It freely passes vapor.
Duane J
I don't see any diagonal bracing for lateral loading such as wind loads. Having steel tension cables provide lateral loading would be a big plus.
The straw is basically insulation which is a huge issue in the Far North. It really doesn't have much structural strength and will shift and settle with age. But it is excellent cheap insulation, especially if treated with fire retardant and some sort of pest control.
The standard stud wall construction was created to provide a very simple system that provided for both vertical and lateral loading. Once you learned the structural requirements it was easy to build and very easy for building inspectors to verify the structure was safe. Post and beam is requires a bit more care to avoid a sudden failure. One rotten post footing can have a great deal of impact.
Regarding vapor barrier....
Wood rots with moisture. I'd exclude the moisture with the vapor barrier on the exterior. At least that was commonly accepted in rainy Oregon. Humidity on the interior of a home can be controlled by keeping the home below about 28 degrees centigrade. The amount of water in the air is much less below that.
Termites love fungus, and fungus loves dark humid places. So exclude the dark humid places. That means putting a vapor barrier on the ground in the crawl space too and NO plumbing leaks.
I've repaired an awful lot of termite and dry rot damage and I am not sure that Duane's approach would prevent such in all cases. Humidity as a cause of rot has a lot to do with dew point changes. Wood homes that are rot free anticipate where moisture causes problems and try to keep the wood dry. Simply, dry wood doesn't rot and wood under water does not rot - it is an alternation of wet and dry that takes its toll.
Vapor barrier and modern windows do tend to make extremely tight houses and these can create modern problems of how humidity is handled - such as condensation on the interior of windows running down and rotting sills below windows. When a door is opened to the warm humid outside, wet air rushes in and the cooling seems to happen on the glass first. This has nothing to do with vapor barriers, but humidity gets in and converts to run off on cold surfaces. I have used tile window sills instead of wood on the interior to sucessfully prevent rot. Cold humidity is not as much a problem and usually resolved by a well constructed and well sealed exterior. Bathrooms and kitchens rot sooner as water and steam from bathing and cooking are present, also poorly vented laundries.
All this is certainly NOT a 20 hour robot built home. But the point is that good building design is very much about details being properly executed and these things add to the cost and labor.
Many traditional homes have done quite well with a good coat of paint being the only moisture barrier. But these days we have dramtically increased insulation. I can't imaginge why one should bother with Tyvex or any other building paper if it did not at least provide a moisture barrier. One often sees that by holding back moisture, it also stops migration of termites and dry rot to the underlying structure.
Not sure what the difference betwen vapor barrier and moisure barrier really is or if it is worth noting. This is not like Goretex rain coats. The wood must stay reasonably dry to not deteriorate.