Straw

[LordyLordy]

Originally Posted by swagger

Not very fire resistant, though.

You have no clue what you are talking about obviously

Straw bale homes are VERY fire resistant, been tested quite a few times by state authorities in at least one state and a few University studies. At the density of the straw used in a house and the pressures in the walls due to weight, plastered inside and out - the straws is very compressed and completely inflammable.

[LordyLordy]

Originally Posted by ChrisC

Straw bale homes needn't look like the trendy straw homes that have been a subculture thing since the hippie era. More traditional straw bale homes typically look like any other home at first glance. It's just that the "insulation layer" is quite thick. You have to remember that many of these old homes were built with typical framing. When we say straw bale homes, many people think of basically living in a haystack--not traditionally the case. It would be like saying today, "I live in an insulation home"... which would be a stack of insulation panels with a tunnel leading into a hollow spot. Not typical, right? Just think of the straw as being like our fiberglass insulation of today. Same applies: our homes are not built of insulation, they just have insulation in them.

Same applies to "sod homes." Traditional sod homes could be built to look like any other home--just sod core in the walls.

The main problems with building a straw bale home are moisture and size. You protect against moisture by:
1. Building with straw bales above ground, typically at least a foot or two of concrete foundation wall above ground first
2. By having bigger roof overhangs
3. By plastering the outside with plaster

If you follow the above three, you will not have any moisture problems.

As for size: a home larger than 30x30 built without a frame (only straw bales on a concrete foundation, bales are impaled on rebar, tied to the ground with a strong cable looping under the roof ) will be OK. If you have anything larger/longer you will most likely see the straw bales sag in the middle due to roof weight. Some people put wooden rafters on top of the straw, some put concrete, there are a few systems to do this and potentially avoid the sag but obviously the longer the building, the less support straw will provide for the roof. You don't have to build a full wooden frame, you can provide strategically placed beams coming out of the foundation...

A 1,000 sqft straw bale home build on a stone/concrete foundation (cheapest is to make it using slipforming) would need no wooden frame, thus saving a lot of the costs and pollution. A straw bale around here costs $5 delivered, a 1000-1100 sqft home would need about 350 of these guys so the walls would cost about $2000 tops. If you do your own foundation (you only need the carrying walls the width of the straw bale plus extra few inches to hold the floor joists - your floor can float in air and be supported with concrete piers along the way) and put your own roof - the whole house (unfinished inside) will cost you no more than $10-15K including all doors and windows and plastering. We are talking super insulated place, one wood stove or pellet stove and an evaporative cooler and you are good to go. A few solar panels on top and you are energy self-sufficient....

[MTSilvertip]

Originally Posted by swagger

Not very fire resistant, though.

And what about the big bad wolf huffing and puffing and blowing your house down???

Actually, due to the surface area and low oxygen of the bales, they are a lot like books when closed, they don't burn well.
That said, in the right conditions they can smoulder for a long time. Farmers around here burn old stacks that are no longer fit to use, and there can be smoke still coming up over a month after the fire is out.

I have actually seen some experiments done using bales of shredded documents in place of straw. The one I saw was using detergent boxes because the plastic coating made the boxes nearly impervious to fire.
The Paper Bale House | SKI Magazine

Others like in work done in Germany leave the bales open to the air to dry out.
Recycled Paper Bale Being Used in Building Construction - TechTxr

There are definite low cost advantages as well as thermal to this kind of construction, but for my money I would have a strong frame of timber or concrete and fill with paper.
You can achieve many of the same advantages using blown cellulose insulation in regular stick built construction.
Cellulose Insulation – Blown Cellulose Insulation

Personally, if the material, (either paper or straw), is covered, I would want a seal against mold for these kinds of construction especially in a humid climate. Perhaps a vacuum seal plastic prior to adding the stucco covering. Moisture is going to be the big enemy of this kind of material.

That and Big Bad Wolves

[bongo]

Very interesting paperbale houses, MTSilver! Thanks for posting them.

[PedroMartinez]

Pretty cool info.