STRAWBALE HOME CONSTRUCTION (Overview)

[I.M. Boggled]

STRAWBALE CONSTRUCTION


Considerations:

Strawbale construction is the use of compressed blocks (bales) of straw, either as fill for a wall cavity (nonloadbearing) or as a structural component of a wall (loadbearing.)
In each case, the interior and exterior sides of the bale wall are covered (by stucco, plaster, clay, or another treatment .)
This sandwich of straw and plaster can offer structural properties superior to the sum of its parts.
Both categories of strawbale design divert agricultural waste from the landfill for use as a building material with many exceptional qualities.

Advantages of strawbale construction:

* Excellent thermal and acoustic insulation – enhances comfort throughout the year
* Reduced construction waste: the main building material is a ‘waste’ and excess straw can be used on-site in compost or as soil-protecting ground cover
* Potential for major reduction in wood and cement use, particularly in load-bearing strawbale designs
* Requires no toxic treatments; can be good for chemically-sensitive individuals
* Can be highly resistant to vermin (including termites) in use, but biodegradable or reusable at the end of its useful life
* Can be economical. Strawbales are inexpensive, occasionally free, and owner/builders, unskilled volunteers, friends, and family can contribute significantly to labor.
* Aesthetic flexibility – from conventional linearity to organic undulation
* Usable in new construction, additions, and remodels

Considerations in strawbale construction:

* Straw bales may be plastered inside and out to provide thermal mass and, like standard construction, the walls must be protected from moisture
* Strawbale can be more resistant to termites and vermin than stick construction, but (as with any type of construction), elimination of cracks and holes is key.

Disadvantages of strawbale construction:

* If labor is done primarily by building professionals, the square-foot cost of strawbale construction can cost just as much as standard building methods
* Special measures must be taken to provide nailing surfaces, since straw bales do not hold nails as well as wood

Summary: Strawbale Construction

Standard wood-frame residential construction practices require specialized skills and tools, as well as large quantities of wood, concrete, gypsum board (drywall), and fiberglass. While the environmental impacts of these materials are described throughout this guide, it's worth noting that construction in the United States consumes about 10% of the global industrial lumber harvest in a nation is home to about 5% of the world's population. Similarly, concrete, drywall, fiberglass insulation, and other building materials each have significant environmental impacts during extraction, processing, and disposal. Some standard building materials are also potential problems during application and use, such as toxic adhesives, binders and sealants. Strawbales are one of a range of ‘alternative’ building materials that help reduce or eliminate many environmental problems because they use plentiful, non-toxic, reusable, and biodegradable elements to build durable, comfortable, healthy places to live and work.

Strawbale construction was invented more than a century ago on the Nebraska plains, where waste straw was plentiful and wood was in short supply. Loadbearing strawbale construction, where the roof is directly supported by the bales, is termed “Nebraska-style,” while nonloadbearing strawbale construction involves post-and-beam support for the roof and the use of bales as a fill that insulates and defines the shape of the wall cavity. Greater familiarity and adaptability have made post-and-beam strawbale construction far more common than Nebraska-style. California Health and Safety Code Section 18444.40 – 18444.41 limits loadbearing strawbale structures to a single story in the absence of supporting engineering calculations.

Strawbale construction has been growing in popularity since the 1970s, and there are now thousands of strawbale homes in the U.S.
By contrast, stick-frame construction has been standard practice in the United States since the end of World War II, but it remains uncommon in parts of the world with fewer timber resources.
http://www.ecoact.org/Programs/Green_Building/green_Materials/strawbale.htm

 

[I.M. Boggled]

STRAWBALE STRUCTURE GUIDELINES:
Summary Recommendations and Brief Overview

Straw bale construction exhibits R values from R-30 and up to R-45.

The bales are typically covered with concrete mortar/stucco, achieving a high degree of fire resistance.

Two hundred million tons of straw are burned annually in the US. The stability and lack of weathering in straw is not desirable in agriculture but quite desirable in construction.

Straw in straw bale structures has not shown evidence of termite infestations.

Dry bales should be used. Moisture levels in use and in storage should be below 14%. The bales should be kept dry after construction.

Bales are anchored to each other when stacked by stakes of wood (1x2x36), rebar (#3 or #4) or bamboo that penetrate at least two bales. Another less popular method uses mortar between bales. A new method uses bamboo (or similar) stakes on both sides of the bales, tied with wire or twine, "corsetting" the bales. Such anchoring is generally accepted to be primarily necessary to keep walls from toppling during construction; well applied plaster will usually provide sufficient stablility once complete - though by that time, whatever pinning method was used is embedded in the walls.

Bales can be used flat or on edge. They are best used flat for structural purposes. Plaster will also "key" into the ends of the straw when bales are laid flat, whereas bales on edge will have the long length of the straw on the wall surface, providing a weaker bond between the plaster and bale.

Bales come with two-wires or three-wires (or strings) holding them together. Two-wire bales weigh about 50 pounds and three-wire bales, 75-100 pounds. Two-wire bales are usually 14 inches high, 18 inches wide, and 32-40 inches long (typical in Texas). Three-wire bales are 16-17 inches high, 23-24 inches wide, and 42-47 inches long (typical in western states).

Bales should be firm and strung tightly with either baling wire or twine. Half bales and whole bales are needed so the bales are staggered when stacked.

A timber frame construction (or steel or concrete) can use bales as infill. The frame adds to the expense in materials and in labor for constructing it and then working around the frame with the bales. However, this approach will be more readily received by building officials.

Window and door frames and headers can be made from wood. Windows and doors are typically accentuated towards the interior or exterior of the opening creating a deep well. Care is needed to avoid water entering or collecting in these areas.

A wood plate or concrete beam (or bond beam) is placed on top of the wall. Trusses or roof framing can be set on this. A threaded bar can penetrate through the top bales and be fastened to the plate or beam for added roof stability

Poultry netting can be mounted on both sides of the walls for plastering. Stucco lath is used around windows, doors, and corners for added strength. The wire netting and lathe are typically held against the bales by wire ties through the bales or pins into the bales.

Utilities can be laid in the walls as they are built, laid against the bales after the walls are built or run in moldings, interior walls, under floors, or in the attic.

Structural, or "Nebraska Style," straw bale construction requires that the bales sit for a short period of time to complete any settling before stucco is added, or that the walls be mechanically pre-compressed. If the bales are firm, there will be very little settling (typically less than 1 inch). A wire tie-down system which is connected to the foundation and the top plate, application of downward pressure using a front end loader bucket or similar, or any of a number of other techniques have the ability to firm up the wall and compress it to compensate for any settling concerns.
...
http://www.greenbuilder.com/sourcebook/strawbale.html
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http://www.redfeather.org/programsStrawBaleConst.html

Red Feather educates and empowers American Indian nations to create sustainable solutions to the severe housing crisis within reservation communities.
While focusing public attention on the intergenerational poverty and acute community development problems that plague American Indian reservations, Red Feather teaches affordable, replicable and sustainable approaches to home construction.
Red Feather organizes volunteers, and, alongside tribal members, builds desperately needed homes.

 

[Guest]

I really dont understand those american houses... european brick and concrete houses are great... then you dont have to cry that wind crushed your wood frame house...

 

[bartender187]

and he huffed and he puffed....

pass that shit ; 0

 

[Guest423]

interesting...i never seen or heard of anything like that before...nothing beats an old log cabin though!

 

[Guest]

quit hatin on my house yall

 

[vhGhost]

and he huffed and he puffed....

pass that shit ; 0

OMG lol .. i actually thought the same thing when i saw the pic

 

[I.M. Boggled]

Why Strawbale?
...because it bums dem big bad wolves right out
...they also tends to be Fire, hurricane and torrnado proof...

Buildings are designed to temper our environment; to keep us warm in winter and cool in summer; to keep out bugs, insects and other people's pets; to keep out the rain and snow; to shield us from wind and protect us from fire; and to make our homes quiet and safe.
We ask our walls to do all of these things, plus more--we want the walls to hold up the roof and protect us from hurricanes and earthquakes.

Plastered straw-bale walls do these things simply and very well.
Wood and steel systems often require that several complex components must fit together to do the job that a straw wall does simply and easily.
A structural straw-bale wall system--bales with plaster--requires no special detailing to do the job we ask of it.
The structure itself tempers our environment.

Of course we all know that straw is a good insulator.
In addition, and at no extra cost, a plastered straw-bale wall provides abundant thermal mass.
Thermal mass is almost as important as insulation in creating a tempered, energy-efficient environment.

A plastered bale wall provides a good barrier against air and water coming from the both inside and out.
At the same time, bales can hold up the roof. Because bale walls are highly fire resistant, this structural system comes with its own fire proofing.

We would expect this kind of performance to come from a high-tech, state-of-the-art product, something manufactured from exotic materials, costly and difficult to obtain.
But bales are a waste product--cheap easy to obtain without damaging our environment or wasting resources.
When straw-bale is appropriate for a project, it is usually the most efficient system.

We like wood--in fact we love wood.
It's a beautiful material.
We try to use wood which has been responsibly grown and harvested.

We also like straw-bale walls.
They're cozy and quiet.
Light comes in beautifully through deep windows.
When we build with bales, we try to design the other components of the building to be as environmently sound, efficient and beautiful as the walls.

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Straw-Bale Building FAQ's
http://www.skillful-means.com/strawbale/papers/strafaq.htm

 

[I.M. Boggled]

Natural Building with Lime
Plasters, Mortars, and More
http://www.northcoast.com/~tms/lime.html

There is a renewed interest in using lime, gypsum, clay and earthen plasters for strawbale and other natural material houses. Many people know that lime has been used for over 5,000 years, most notably by the Romans to make mortars and plasters. In the cold northern regions of Scotland and Wales lime plasters protect even stone walled builings from harsh weather and fierce rains. Lime "harling" ...a thrown lime plaster...is used as a sacrificial coating to keep water from cracking and damaging stone walls and mortar joints.
When lime is used on strawbale and earthern walls it provides a vapor permeable skin which allows moisture in, and out again, before it can seep to the wall and cause damage. And lime offers many more advantages.

Alternative builders are choosing lime-sand plasters instead of Portland cement based plasters, and achieving excellent results. Cement, while cheap, and popular in traditional stick-frame building, cannot compete in performance with lime.
The National Lime Association recommends a small portion of cement for guaging in a 1:2:9 cement:lime:sand, mortar or plaster. Many builders are eliminating cement altogether. Some are using quicklime (when it can be obtained), slaking it, and adding Prickly Pear Cactus gel (Nopal) to mixtures as a binder. Most builders can use hydrated lime soaked in water to make a plastic, workable mix. Simple, old fashion limewashes are becoming more popular too.

Straw bales perform well with lime based plasters and earthen plasters.

Lime plasters dry more slowly, gaining strength over time, which is their advantage for owner-builders. Lime in building use is very forgiving, and can be reworked for days after placement, unlike cement which is meant to set-up in hours, and cannot be altered at all once mixed.


Wide window ledges are the result of the straw walls

 

[Verite]

I would hate to find out if mice can live on straw.

 

[Guest]

Cool thread Boggled...I know a fella who lives in Idaho that has him a strawbale home. You wanna talk about warm and quiet?

Seed

 

[I.M. Boggled]

Straw Bale Construction
(print version)
From Wikibooks, the open-content textbooks collection


http://en.wikibooks.org/wiki/Straw_Bale_Construction/Print_version

While use of grass-family plant fibers has long been a part of building methods worldwide, dating far back into prehistory, actual straw-bale construction was pioneered in Nebraska in the United States, in the late 19th/early 20th century, in response the then-new availability of baling machines and the lack of significant amounts of timber or buildable sod needed to build barns and housing in the Sandhills region. Under the Homestead Act of 1862 and the Kinkaid Act of 1904, the "sod-busters" were required to develop and live on their new property for five years in order to maintain ownership; building housing was a legal requirement. The straw-bale house was first seen simply as a make-shift structure, to provide temporary lodging, until enough funds were available to pay for the shipping in of timbers, to build a "real" house. However, these homes quickly proved to be comfortable, durable, and affordable, and so became regarded as permanent housing. Over the past century they have indeed outlived many neighbouring timber-frame buildings, and a number are in continuing use today and beginning their second century.

After World War II a scattering of U.S. veterans turned to straw-bale for shelter, but modern straw-bale construction experienced a re-emergence in the late 1970s, after the 1973 energy crisis helped bring issues of real sustainability to the forefront, with first examples built primarily in the southwestern United States. Now, they are being built the world around, from northern Canada, Mongolia and post-Chernobyl Russia, to Mexico, Australia and New Zealand. Because it is based on an inexpensive and renewable so-called "agricultural waste product," with a technique relatively simple for beginners to implement, involving few synthetic chemicals and providing effective energy-conserving insulation, it continues to grow in popularity, especially with do-it-yourself-ers "owner-designer-builders" and other proponents of sustainability.

(@ LINK)

CONTENT:
o 1.1 History
o 1.2 Current Perspective and Regulations
* 2 Materials
* 3 Characteristics
* 4 Acoustics of straw bale structures
o 4.1 Links
o 4.2 Insulation
o 4.3 Thermal mass
o 4.4 Passive Solar
o 4.5 Availability, types and cost
+ 4.5.1 Availability
+ 4.5.2 Types
+ 4.5.3 Cost
o 4.6 Resistance to pests
o 4.7 Resistance to fire
o 4.8 Limits to structural strength
o 4.9 Design and construction challenges
o 4.10 Foundations
o 4.11 Walls
+ 4.11.1 Straw Bale Infill
+ 4.11.2 Load Bearing Walls
+ 4.11.3 Curved Walls
+ 4.11.4 Structural Capabilities of Bale Walls
o 4.12 Finishes
+ 4.12.1 Cement/ sand stucco
+ 4.12.2 Clay plaster
+ 4.12.3 Lime plaster
+ 4.12.4 Tadelakt
+ 4.12.5 Floor finishes
o 4.13 Openings
o 4.14 Roofing
+ 4.14.1 The Green Roof
+ 4.14.2 Roof and Ceiling Insulation
+ 4.14.3 Related Links
o 4.15 Pushing the Limit
+ 4.15.1 Arches and vaults
o 4.16 Related Resources
+ 4.16.1 Content
o 4.17 Useful Software
+ 4.17.1 Technical Studies, Reports and Tests
# 4.17.1.1 General
# 4.17.1.2 Acoustics
# 4.17.1.3 Insulation
# 4.17.1.4 Fire Safety
# 4.17.1.5 Building Codes
# 4.17.1.6 Construction Strength
# 4.17.1.7 Moisture
# 4.17.1.8 Studies in other languages
+ 4.17.2 Worldwide organisations and contacts
# 4.17.2.1 The Americas
# 4.17.2.2 Europe
# 4.17.2.3 South Pacific
# 4.17.2.4 Email Lists
+ 4.17.3 Straw Bale Building Registries
o 4.18 Resources on the internet
+ 4.18.1 Wikipedia, the free encyclopedia
+ 4.18.2 Wikibooks, the open-content textbooks collection
+ 4.18.3 External links
* 5 Bibliography
* 6 Glossary of Terms

http://en.wikibooks.org/wiki/Straw_Bale_Construction/Print_version