ProVillage


ECO-BUILDING – PART 12 – Electrics in a Straw Bale House

When having electrics in a straw bale home, one will need to know how to install it, as it might might be so that electricians will not necessarily have earlier experience with straw bale structures.

All of the wiring is to be hidden behind the plastered wall, or made to run in required places behind a special panel, so it is better to get it done right the first time. The panel solution also makes it easier to fix faulty wiring, if the need arises.

The wiring can also be placed to run in a tube which makes the installation easier.
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The idea in a nutshell

village layout sample

A description of the project in a nutshell can be downloaded from the following address:
https://provillage.files.wordpress.com/2010/01/concept-description-eng.pdf
The material has also been presented to some local decision-makers, and is pending for a decision.
We are naturally also interested in having cooperation with people and instances interested in similar ventures and ideas.
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Projektin kuvaus pähkinäkuoressa löytyy allaolevasta linkistä:
https://provillage.files.wordpress.com/2010/01/konseptin-kuvaus-20100112.pdf
Materiaali on myös lähetetty joillekin kunnallisille päättäjille, odotellessamme päätöksiä.
Olemme luonnollisesti myös kiinnostuneita yhteistyöstä eri ihmisten ja osapuolten kanssa, jotka ovat kiinnostuneita samanlaisista hankkeista ja ideoista.

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ECO-BUILDING – PART 11 – Preparations for Plastering a Straw Bale House

A job well planned and prepared is a job half done. A quality plaster job starts before the plaster is brought to the site. The condition of the substrate, or the base surface to be worked with, is very important – as the plaster can only be as strong as the substrate it is attached to. Straw generally makes a great substrate for a plaster, as so does a mesh – if any mesh is to be used.

The transition points of bale to wood must also be detailed, because they have their own rate of expansion. Because these two materials expand and contract at a varying rate, many cracks will appear if the transition points are not properly detailed with a plaster lath.
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plaster and wood transition points

One method is to cover all wood with roofing felt to isolate the wood from the plaster. One can also use a plaster lath to give the plaster something to hang on to. The plaster should always have some surface to hang onto, and hang on its own without any structural support. This is even more important around doors and windows as well as at the intersections with the ceiling.

burlapOn exterior surfaces, all wood needs to be covered as described above and any large gaps need to be filled.
Materials used for doing the filling are cob, light straw clay, burlap, spray foam (PU-foam) or other suitable materials.

When the plaster is to be applied, the walls should be tight and solid. All wooden parts should be covered and the mesh should be attached firmly to the wood structures and/or sewn through the straw bale walls.

All holes and gaps should be filled firmly so that no deflation occurs. It is also good to keep the site clean of straw and other debris, so one can walk safely around the structure.

The floors should also be covered so that dropped plaster will not have the possibility to mar it.

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ECO-BUILDING – PART 10 – Working the Bales into Shape (continued…)

As an addition to the previous post: The nooks and niches in the walls can be made into various forms and for various purposes.

Nooks and niches are possibilities to remember, when you build straw bale houses

In this case too, only the imagination sets the limit.

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ECO-BUILDING – PART 10 – Working the Bales into Shape

Cats loves to live in straw bale houses with smooth and beautifully curved windows and elements

A straw bale house is commonly equipped with soft curves. The advantage of having softer curves around the windows is that they allow more direct light to filter into the rooms while also acting as reflectors for indirect light. These curves are easy to make and have an additional effect on the aesthetics of the house.

Mesh

When a mesh is used for the engineering of a building, the creation of curves becomes quite easy. The mesh provides a form for the straw. The desired shape is created when the loose straw is placed behind the mesh, which is then nailed to the framing. For some shapes, such as curve around a window or door, additional plaster may be needed.

When using a metal mesh however, there is always the risk of creating a Faraday’s cage.

Niches and nooks

The characteristic of the walls being relatively thick makes it possible to create niches and/or nooks, if one desires. The spaces can be carved into the walls after the bales of straw have been stacked. They act as a decorative addition to on the walls, and can also be used to highlight an item in your home. These nooks can also be made into an ideal feature if a light fixture is attached to them.

These are a number of different options available as for the mesh – welded wire mesh, plastic mesh, chicken wire. It is worthwhile to experiment with various methods regarding to various usages.

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ECO-BUILDING – PART 9 – Custom bales

A lot of custom trimmed bales are required in any straw bale home. The areas with windows serve as good examples. The task is to make a rectangular bale to fit. During the process one needs to know how to cut and retie bales, and how to notch and shape them.

Re-tying

The tip of a baling needleCutting the bales is not as easy as one would think. A bale of straw cannot be worked on as one would work wood. The bales have a tendency of breaking apart if not worked on in the correct manner. When working with bales one has to mark the bale where one wants a cut to be made and then proceed cutting the bale while incorporating a tool called a baling needle to retie the bale in parts where one will not be cutting the bale.

With a good baling needle you can retie a bale and create two custom bales from one in a short amount of time. The most important knot to know here is the Miller’s knot.

Notching and shaping

Notching and shaping require the use of a chainsaw and a can of spray paint to make the markings of where you need to cut. Notches might be needed to fit the posts and other framing components. A time-saving method is to slightly over-cut the needed part for the posts and then stuff the space with straw if needed. Be careful not to cut the string of the bales while notching. Some notches can be more intricate than others.

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ECO-BUILDING – PART 8 – Framing

Post and beam systems

Straw bale building are not the same as conventional buildings. This is an advantage and precisely the reason why some people incline to building straw bale houses. The best thing to do is to use framing systems which are adaptable to the bales found for your build. For most non-bearing systems, the framing is a post and beam or a modified post and beam frame.

In a non load-bearing construction the whole strength of the home is in the construction itself. This provides a load path for the roof and floor systems. It also acts with the shear strength for the building. This system holds the house up.

A similar value can also be given to the bales and the sorts, even though the frame is often regarded as the actual structural system.

Special considerations

Mesh used to reinforce the surface renderUsually a conventional frame is to be changed for straw bale purposes in a number of ways. First, there needs to be enough room for the adequate nailing of the lateral shear mesh around the doors and windows. For making this, an additional trimmer may be required depending of the inclusion of the exterior trim. There also has to be enough nailing surfaces along the base of the wall system for a possible mesh to be used.

Framing layout

Unlike conventional construction, the framing does not land on four foot centres and in four foot modules to accommodate plywood sheets. Instead, the layout of framing is designed to fit the size of the bales and support the calculated loads. The more accurate you are with framing to the bales sizes, the less you will have to do during the baling stage. It is also important to pay attention to the header and plate height around the house. The goal is to fit the bales tightly under the top plates to help squeeze the bales and strengthen the wall. The windows and door header heights should be lined up so that numerous layers of stuffing are not required to continue the running bond of the bales.

Roof design

Hip roofRoof designs do not change that much to the conventional roof. When making a gable roof, more custom made bales have to be used, and some designs require more work to be adapted to a straw bale home. As an example: In a gable roof design, more custom-made bales have to be made, as one builds more towards the roof line.

Gable roof

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A roof design can also help diminish the darkness sometimes created by the thick straw bale wall. By making an open roof design or dormers, more natural light can reach the room, thus brightening a room that may otherwise seem dark due to window size and orientation. The roof overhangs are should be quite remarkable in order to protect the construction from rain and/or snow.

Toe ups

The creation of toe ups is a part of the framing process. In a straw bale construction, toe ups are a necessary part of the straw bale construction. They provide adequate nailing surface for the possible wire mesh and separate the bales from the concrete and create a so-called moisture break. Should there occur a water break, the toe ups keep the bales dry and protected. The toe ups can be constructed using pressure treated 4×4 material, gravel and tar paper. They also provide a foundation or base for the bale anchors, which are required by code in various countries. The bales are attached to the toe ups, and the toe ups are attached to the concrete. In this way, the entire system is anchored to the foundation.

Some code books require the use of re-bar impalers for the system, but some nails applied to the toe ups have also been accepted in certain areas. The nails create a much stronger connection for the bales and do not interrupt the separation of the bales from concrete the way a rebar sections buried in the concrete does. Many building departments have easily accepted this kind of change in the construction.

Straw bales stacked on toe ups in a construction

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ECO-BUILDING – PART 7: THE BEST BALES FOR THE JOB

Once you have gathered some knowledge of the land and a design which you have found appropriate, the origin of the bales is to be found out.

It would be helpful to know exactly how big the bales are, and which kind you are going to supplied with – and at least their approximate dimensions. This is crucial during the design and engineering of the framing.
There are many farmers with available bales, so there is also a lot to choose from. Do meticulous research on the quality aspects of the bales. The difference in price does not vary that much, and this little extra effort is worth its while it in the end.

Visual inspection

strawbalesThe colour of the bales tell a lot of the history of the bales: If they have seen weather or not? Have they been stored properly? If there is a lot of white powder coming from the bales when they are agitated, it can be considered as interior mold. This can also be judged by smell; in the case of mold, the smell is unmistakably musty.
If the the visual inspection reveals that the bales damaged by water, moldy or otherwise not in good condition, it is advisable not to use the bales in the construction because then the whole construction would be placed into jeopardy.

Bale density

One important factor when choosing the bales is the density of the bales. Most building codes which recognize straw bale construction commonly require a specific density for the bales.
Calculating the density in some regions is usually calculated by the dry density of pounds per cubic foot (1.10 kN/m³).
It is essential to know the density of the bales in order to guarantee the building inspector of the quality of the bales.
A field test can be conducted in order to make sure of the density of the bales.

Moisture content

moistureThis might be most important factor when choosing bales. If the moisture content reaches over 20% , this level is enough to give a habitat for mold and decay. It is difficult to reverse the process of mold and the process produces two things the bales need to rot: moisture and warmth.
When measuring the moisture of the bales, keep in mind that the bales take and lose moisture in relation to the ambient moisture. When reading the moisture content, the reading should come from the bales and not the atmosphere.
It is not recommended to measure the moisture content in the early morning, when the dew may affect the reading.

straw baleQuestions such as what science do the local codes require in making the decision also have to be answered. And furthermore, it is much more desirable to have the straw bales from the local area for the building to have a lower impact towards the environment.

After you have found a suitable supplier concerning the bales you can move on to the next phase of designing and construction.





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ECO-BUILDING – PART 3: Strawbales are outstanding as insulation!

The construction of strawbale homes has grown enormously around the world. The reason for this is the cost-effectiveness of the building material, and that the normal supporting structures and the clay-plastered straw bales replace many other materials, such as tile or wood cladding, wind-proof boards, insulation, plastics and decorative boards.

A large straw bale house - Wikipedia

Even large houses, such as exhibition halls of thousands of square meters, are being built using straw bales.

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From our three separate ’ProVillage’ -documents you can get a relatively clear idea about our project:

The documents can be found both in Finnish and in English.

Downloading might take some time, because the files have an approximate of 130 images.

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Wikipedia-Matawa_straw_bale_library

Here a library has been constructed using straw bales.  The wall support structures have been crafted for the windows. After this the walls have been plastered with a clay and sand mixture to leave it to a distinctive light colour.

straw-bale-house-window-installetion

The supporting structures are made in the same fashion as in the usual building of a house. Here a window-area has been prepared for the application of the external render.The window benches and the window frames are connected firmly together to the supporting structure. In the meantime, the ‘packages’ of straw are tightened and ‘barbered’ to a uniform surface.

Straw-bale-house-under-construction

The window benches and the window frames are connected firmly together to the supporting structure. In the meantime, the ‘packages’ of straw are tightened and ‘barbered’ to a uniform surface.

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The insulation capability of a straw bale structure

The Finnish thermal insulation requirements will tighten remarkably by the year 2010.

”The U-value (or U-factor), more correctly called the overall heat transfer coefficient, describes how well a building element conducts heat. It measures the rate of heat transfer through a building element over a given area, under standardized conditions. The usual standard is at a temperature gradient of 24 C°, at 50% humidity with no wind (a smaller U-value is better). U is the inverse of R with SI units of W/(m²•K)”

Source:  http://en.wikipedia.org/wiki/U-value#U-value

The U-value (previously known as the K-value) in part C3 of the collection of building regulations. —– The U-value is to indicate the thermal insulation of various structures in a construction.

The smaller the U-value, the better the insulative capabilities of the material.

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PASSIVE HOUSE:

“The term passive house (Passivhaus in German) refers to the rigorous, voluntary, Passivhaus standard for energy efficiency in buildings. It results in ultra-low energy buildings that require little energy for space heating or cooling”

Source: http://en.wikipedia.org/wiki/Passive_house

All or nearly all of the heat energy needed  is obtained from solar energy and the heat generated from the living in the house.

A passive house does not have an actual heating system. The outer shell of the house has to be well insulated and tight.

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550-1

The pictures above and below have been taken from a guide book which is published by Amazonails, which also can be downloaded in PDF-format from:

http://www.amazonails.org.uk/UserFiles/files/strawbaleguide.pdf

550-2

The following is a table of summary:

The tightening demands on external insulation of various building materials

building regs

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The situation is such that if one was to use 45 cm of mineral wool on a wall, that would also fall into the requirements of a passive house, but at the same time would be very expensive.

So it can be deducted that in reality strawbales are the best and most cheapest insulation material, falling greatly below the norms with its values even under tightened circumstances.

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Here you can find a lot of literature in English on the topic:

http://www.amazonails.org.uk/?contentId=59

Pictures :  http://www.StrawBale.com and http://www.LearnStrawBale.com

An information package can also be found there which can be distributed freely.

Videos can be seen here => http://www.StrawBale.com/videos


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Eco-building – Part 1: Establishment of a family-oriented village for artisans

https://provillage.files.wordpress.com/2009/09/stones-and-pallets-as-ventilation-under-thr-straw-bale-construction

Displayed  are some on the main building materials incorporated with the construction. Picture: Tero Syvänen”

https://provillage.files.wordpress.com/2009/09/artist-straw-bale-home-ground-floor-taiteilija-olkipaalitalo-alakerta

A conceptual model of the house intended for construction.
The facade has been omitted in the picture in order to give an impression
of the dimensions.

Presently our introductory files are being translated into Chinese, Russian and Arabic – and their English and Finnish versions can be downloaded from here.

Other languages to follow.  We can be contacted at: provillage2010@gmail.com

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