Pa floris the development conventional american building elements made from bamboo

• Marketing factors for bamboo based product in the USA • To improve bamboo’s material performance by using sustainable technologies • The introduction of improved designs to create func

The development of

"Conventional" American building elements

made from bamboo Floris Keverling Buisman, Msc

Common Ground Community/Blue Moon Grantee

505 Eighth Ave, 15th Floor

New York, NY 10018 Phone: +1 212 389 9364

Fax: +1 212 389 9312

• Marketing factors for bamboo based product in the USA

• To improve bamboo’s material performance by using sustainable technologies

• The introduction of improved designs to create functional products with a wide market potential

• Scope of market for building materials and their price range

Exploration of these factors led to the development of several possible

construction element/modules that have a synergize bamboo fast growing aspects, can be produced locally in China and won’t require construction practices in the USA to change their customs to drastically Implicating that the bamboo products will both bring income to the producing county, as well will be easily implemented in the conventional building industry in the USA

Taking all the factors together, the hybrid level (combination of elements of traditional processes with elements of advanced treatments, non-traditional processes and the design input) of technology should result in a win –win situation Generating more local benefits in China while providing the USA with a better-engineered and more sustainable construction product

To introduce these materials on the USA market, various tests will have to

be done on the different materials, so that they conform to the required standards as demand by the (local) building codes

The end result of this research is a recommendation of which bamboo based materials (studs, in- and exterior panels and doors) will be feasible to be introduced in the USA

2.2.2 Indoor environmental quality 8

3.1 Dimensional lumber replacement 16

4 US market for industrial bamboo construction products 41

4.1 Demand and prices of wood based products 41

1 INTRODUCTION

Introducing bamboo construction materials in the USA, has to overcome one big hurdle: the conventional western building tradition This grid-lock which

is formed by design customs (architects), building codes (officials and

legislation) and the building industry (manufacturers, suppliers and

contractors) make introducing new and more sustainable products a

challenge To overcome this problem, the products will either have to have

an aesthetic or practical appeal and to ‘break the ice’ have a sustainable appeal, which preferably can be combined with the crucial aspect:

competitive pricing

This implies the following (D Larasati, 2003):“Although these (sic: products)

are promising, there have been no other official test results on bamboo

board’s endurance against weather, fire and chemical substances Bamboo board is commonly used only for indoor construction, therefore the many other obvious possibilities, such as cabinetry and furniture applications need to be explored

This is where designers can contribute their knowledge Industrial design is one of the professions, or knowledge fields, that can be expected to uncover the potential for more creative applications People in urban areas, who responded to the questionnaire concerning attitudes toward bamboo

products, welcomed the idea of improved bamboo products and expected that an exploration of bamboo would lead to new high quality products

Design professionals can be expected to come up with creative, intelligent and appropriate uses of the material With modern applications that can expose its superior qualities, bamboo material will be able to perform

efficiently and prove itself as a competent and exciting material.”

What qualities and potentials of bamboo that can be merged into a

successful material, for which there is demand in the USA construction market? This paper first explores the US marketing factors for bamboo in general Followed by a research of the production process of ‘western’

bamboo products and which improvements can be made for the US market After which common building materials of the USA construction market will

be identified, for which (potential) designs will be identified of their bamboo based counter parts The market potential of these will then be determined

in the next chapter, by looking at the prices of conventional building

products, with which it will have to compete and this will help to set the (target-) price for the bamboo based product Influencing the market

potential on a different level are sustainability, the building codes to be

met/the costs of testing and if applicable aesthetics

2 USA BAMBOO MARKETING FACTORS

Why would there be a demand for bamboo product in the USA? What would

be the interest of architects and owners, to have this un-conventional

material in their projects, houses and offices? An easy answer could be, the looks If the aesthetics are appealing to professionals in the design industry and/or the people that have purchasing power (owners); the product will get sold So making a modern/wanted product is one method to market a

visible building product in the construction industry The cost and other influences are in that case of secondary concern As one can see with Plyboo, (see figure 1 and 2) which is used in luxury cabinetry and furniture in the USA

Figure 1 Plyboo production direction of slits (www.plyboo.com)

The refined properties of this material, the attractive edge and its wood-like handling, offer carpenters options for intrinsic connections/details (see

figure 2)

Figure 2 Hybrid bamboo miter joint (RISDviews – Fall 2005)

The appearance of this material initially has a familiar wood feel to it But

up close it is distinctively different (see figure 3) This grain like appearance

is in general considered attractive and can thus can be left visible under a protective clear-coat (paint), protecting it from scratches and preserving the aesthetic value of this natural product

Figure 3 Front and side of vertical core cross laminate

The high-end look and marketing in that field has had its financial

implications for this product The consumer cost of this material is

presently $180 per 4’x8’x3/4’ sheet (1220x2440x18mm), which is high

when compared to high-quality birch plywood ($75) The reason the product sells must be that it has ‘extra’ qualities that plywood doesn’t have What are these other factors, besides aesthetics, that makes bamboo so attractive, exclusive and thus expensive?

After investigating and getting a price quote from FUSTAR, it seems that prices of Bamboo panels shouldn’t be more $50 This is a wholesale price but a 300% mark-up for shipping, storage and profit margins from the USA Bamboo panel importers raises the price to far to be competative Ways improve price competitiveness with high end plywood is either direct sales (over the internet) by the Chinese bamboo manufacturers or using the

economy of scale and the free market (as has worked tremendously for

bamboo flooring that is now less expensive (as a result demand is growing)

than hardwood in the USA) Meaning that if more bamboo panel

import-companies will compete for the consumers, based on quality and price, the price will go down and quality will be assured At the moment there is only one company importing bamboo panels to the USA, enabling them to

artificially keep the prices high as there is no competition

2.1 Sustainability

In the building industry, the selection of a building material is mainly

determined by its costs and durability However, as sustainability is

emerging as a key issue in the last decade, especially in western countries, the environmental aspects of building materials have also become a

significant selection criterion Bamboo, as a fast growing renewable material with a simple production process, is expected to be a sustainable alternative for more traditional materials like concrete, steel and timber. (P.van der Lugt, 2004)

Sustainable development is the most vibrant and powerful force to impact the building design and construction field in more than a decade

(www.usgbc.org dec 2004) The sustainable properties that are listed above are reasons that demand for bamboo flooring and other bamboo based

products is growing since the public is becoming more aware of ‘green’

architecture and thus the demand for ‘green’ construction products is rising

Bamboo can thus being market as sustainable, but as P van der Lugt’s

(2004) states: Life-cycle-assessment study shows, one has to be careful to call bamboo sustainable because it grows so fast One also has to take into consideration the production process and transportation of the product that can have a large ecological impact and thus diminish the advantageous

aspects of bamboos rapid growth

Compared to wood, bamboo can have certain advantages: The amount of wood required for construction purposes is taxing the regenerative

capabilities of this resource, as well as depleting a critical component in

ecological balance Trees affect water quality, rainfall, and air quality, both

in the immediate region and on a global scale

The principles of sustainability, which underpins the Green Builder Program favors, forest management practices that retain natural forest ecosystems Some of the options associated with this approach are difficult to implement There are very few "certified" sustainably managed wood sources and

certifying groups are still in the process of determining universal guidelines for certification (www.greenbuilder.com, dec 2004) One can conclude that bamboo from well managed plantation can have the competitive edge over wood First it has faster regenerative properties than wood and secondly

could fill the void of the lack of certified wood

2.2 LEED certification

“The LEEDv2.1 (Leadership in Energy and Environmental Design) Green Building Rating System® is a voluntary, consensus-based national standard for developing high-performance, sustainable buildings” (www.usgbc.com, 2005) Point are given in 6 catergories; sustainable sites, water efficiency, energy & atmosphere, materials & resources (M&R), indoor environmental quality (IEQ) and innovation & design process A total of 69 different credits can be achieved A minimum score of 26 points, will get a building a bronze certification Bamboo based construction materials can help the

design/building attain credits in the M&R and IEQ categories

2.2.1 Materials & resources

“Rapidly Renewable Materials

Intent: Reduce the use and depletion of finite raw materials and long-cycle renewable materials by replacing them with rapidly renewable materials

Requirements: Use rapidly renewable building materials and products

(made from plants that are typically harvested within a ten-year cycle or shorter) for 5% of the total value of all building materials and products used

in the project “ (Green Building Rating System, LEED v 2.1, USGBC 2003) 2.2.2 Indoor environmental quality

“Low-Emitting Materials: Composite Wood

Intent

Reduce the quantity of indoor air contaminants that are odorous, potentially irritating and/or harmful to the comfort and well-being of installers and occupants

Requirements

Composite wood and agrifiber products must contain no added

urea-formaldehyde resins.” (Green Building Rating System, LEED v 2.1, USGBC 2003)

See paragraph 2.4.1

2.3 Raw material physics

For the most part, the bamboo culm is valued for the solid (wood like)

material obtained from the lower part of the plant, and the jointed stems that give the plant its distinctive segmented appearance (see figure 4)

Figure 4 Parking Garage in Germany (www… )

It is supremely strong, durable, stable, and flexible Certain species of bamboo possess a tensile strength (or resistance to lengthwise stretching) that's stronger than steel In addition, bamboo has a hardness comparable

to maple wood yet is more far more stable-bamboo materials typically

experience half as much contraction and expansion as hardwoods Bamboo

is also one of the fastest growing plants on earth

Figure 5 The bamboo culm as a finishing material (Hulshof architects)

From an environmental perspective, the benefits of bamboo don't stop with its almost instant renewability There are a host of other factors that make bamboo an ideal raw material in a sustainable world Because bamboo is a grass, it grows from the base up Unlike trees, which grow from their tops and therefore die at harvest, bamboo isn't killed when it's cut Instead, new sections simply grow up from whatever portion is left, and a living root system remains between harvests to hold soils together, prevent erosion, and stop rain run-off (www.gaiam.com dec 2004)

Figure 6 Bamboo used as an exterior finishing material in a Parking Garage in Germany

“The main concern of any actual or potential user of a bamboo house or product is the short durability of the material The service life of bamboo is generally considered as being too short for any worthwhile investment This, unfortunately, is true to a large extent Bamboo has less natural durability than most woods, owing to a shortage of certain chemicals that occur in

most woods but are absent in bamboo.”(J.J.A Janssen 2000) This implies that treatment of some kind is needed to make bamboo durable to western standards But if a large market penetration of bamboo product is sought, one would have to produce product that can be integrated in modern

western construction typologies and not just as a finishing, exotic material (see figure 5 and 6)

2.4 Engineered Material physics

“In Europe and elsewhere some people do buy products made in developing countries, but this can never amount to structural support for the economy

of bamboo-growing countries For that, there has to be bamboo products that can compete with products made from wood or even plastic.”(J.J.A Janssen 2000) Implying that not the culm, a product based on the culm (like traditional bamboo furniture) but a manufactured product made from the culm, is the way to create an increase in demand in Western countries and generate income/create jobs for the population in bamboo-growing

nations

The USA construction industry has a high adversity to new building

materials, as change introduces uncertainties and unwanted risks that

most architects and contractors rather avoid than encounter The materials design should reflect this, meaning that the products will have to have large similarities to conventional building products Again, these bamboo-based products can take advantage of the growing demand for ‘green’ architecture The obstacle of a new, unknown product can be negated Presently,

sustainability is a rapidly growing influence in the American construction industry This can been seen by the number of LEED registered projects, that grew 400% from 2003 to 2004 (www.edcmag.com, 2005) So, in at this time, when demand for sustainable architecture (and materials) is growing among clients the principle “the customer is always right”, will hold through This means bamboo products should take full advantage of their

sustainable marketability One can even increase bamboos given ‘green’ characteristics (rapid renerability), with appropriate manufacturing

practices, as is described in the following paragraphs

2.4.1 The adhesives

The adhesive employed to create the laminated products are all resins that will bond the strips together Some of these solutions have better water-

resistant properties, others have higher VOC emitting properties The

distinction between the formaldehydes (PF and UF), which is toxic under certain conditions and the Soy bean based (green) adhesives will now be further explained, and why this is a concern while introducing materials with these resins on the USA market

Formaldehyde

Formaldehyde is an important industrial chemical used to make other

chemicals, building materials, and household products It is one of the large family of chemical compounds called volatile organic compounds or 'VOCs' The term volatile means that the compounds vaporize, that is, become a gas,

at normal room temperatures Formaldehyde serves many purposes in

products It is used in pressed wood products, especially those containing urea-formaldehyde glues, are a source of formaldehyde These products include particleboard used in flooring underlayment, shelves, cabinets, and furniture; plywood wall panels, and medium density fiberboard used in

drawers, cabinets and furniture When the surfaces and edges of these

products are unlaminated or uncoated they have the potential to release more formaldehyde Manufacturers have reduced formaldehyde emissions from pressed wood products by 80-90% from the levels of the early 1980's

Formaldehyde is a colorless, strong-smelling gas When present in the air at levels above 0.1 ppm (parts in a million parts of air), it can cause watery eyes, burning sensations in the eyes, nose and throat, nausea, coughing, chest tightness, wheezing, skin rashes, and allergic reactions It has also been observed to cause cancer in scientific studies using laboratory animals and may cause cancer in humans Typical exposures to humans are much lower; thus an risk of causing cancer is believed to be small at the level at which humans are exposed.(www.epa.gov, dec 2004)

Urea-formaldehyde (UF) resins are found in wood products that are

intended for indoor use Phenol-formaldehyde (PF) resins are used in

products intended for exterior uses UF resins emit significantly more

formaldehyde gas than PF resins (www.environet.com dec 2004)

PF also changes the appearance of natural bamboo by making it reddish and giving it a characteristic smell (Larasati, 200X) This cannot be judged

as a bad aspect of this adhesive, although this is an important

characteristic which has to be considered for marketing purposes

Soybean based adhesives

Environmental concerns and requests from users for adhesives made from renewable feedstock have caused a resurgence of interest in developing new soy-based products for the wood adhesives industry

Air emissions of volatile organic compounds and hazardous air pollutants contribute to a variety of modern maladies from smog to sick building

syndrome Formaldehyde and phenol based resins have been targeted for replacement The use of soy additives is demonstrating the ability to

stabilize or even reduce total emissions of these pollutants from wood

products

Most USB-sponsored research has concentrated on the use of hydrolyzed soy protein (soy hydrolyzate), used either as a direct substitute or in a

mixture with PF and UF Soy hydrolyzate is made from soy isolate at a yield

of 12 pounds/bushel of isolate Other research has investigated the use of a lower-cost soy flour at a yield of 39 pounds/bushel of flour This product, in combination with MDI, has been successfully used to make OSB in early trials A two-part system of soy hydrolyzate and PRF adhesive has been

commercialized The PRF/Soy2000 adhesive system is a hydrolyzate-based, finger-joint adhesive intended for uses requiring either a nonstructural or structural, wet-use, exterior-exposure end joint The adhesive was developed with funding provided by USB and specifically allows green lumber to be finger jointed Typical adhesives in use today can only bond wood that is dry

(….)PRF/Soy 2000 is accepted by the Western Wood Products Association (WWPA) as an exterior-type adhesive meeting the requirements of ASTM

D2559, or equivalent The adhesive is suitable for the bonding of wood

including finger-jointed lumber of all structural grades

Air emissions of volatile organic compounds (VOCs) and hazardous air

pollutants (HAPs) contribute to a variety of modern maladies, from smog to the sick building syndrome Formaldehyde, a major constituent of many wood adhesives today, and phenol resins have been especially targeted The use of soy adhesives may not replace these compounds completely, but

instead allow continued growth in wood product manufacturing to meet

growing world demand, while stabilizing or even reducing total emissions of air pollutants. (www.unitedsoybean.org dec 2004)

Relative Economics/Supplies of adhesives

Phenol and urea wood adhesive pricing and availability are both subject to the vagaries of the petrochemical industry Phenol demand is driven by

bisphenol A(used for polycarbonate plastics) andcaprolactum (for nylon 6 used in carpeting) Phenol capacity is expected to become very tight as

demand in these areas grows UF is derived from natural gas, with only

about 5 percent of capacity going into adhesives Agricultural uses for

fertilizer and feed additives utilize more than 90 percent of U.S urea

capacity Urea prices fluctuate significantly with agricultural demand, and supplies are seasonally tight Formaldehyde pricing is dependent on

methanol supply and demand Methanol prices were relatively stable for a number of years before spiking in 1994 Soy adhesives, in contrast, are

based on a renewable resource Soy prices fluctuate with world supplies of feed grains and oilseeds (www.unitedsoybean.org dec 2004)

PF resins are more expensive than UF, but the VOC emissions of UF are not

a positive marketing tool if one wants to introduce bamboo based product

on the market as ‘green’ It will have to be investigated what the cost (and other) implications are, if any, if soybean based adhesive will replace (part of) the formaldehyde adhesives This so that a ‘greener’ product can be

introduced on the USA market

“Precious Bamboo® also import glue from Japan which is totally free from

formaldehyde emission and special for Japanese market After stringent testing by MLIT, Precious Bamboo® Flooring has been approved of

marketing in Japan by Ministry Approval.” (www.presiousbamboo.com

2005) Research in 2005, while directly approaching this company, has

proven that these non-VOC emitting bamboo floors, are not higher than

‘regular’ bamboo floors ($17.87/m2 or $1.66 SF, CIF New York) The type of adhesive that is used (imported from Japan according to Precious) is

unknown

2.4.2 Plantations

Bamboo’s green outlook can be further enhanced by sustainable managing the plantations As there is not certification for bamboo yet, as there is for sustainable grown wood (FSC), the customer has to rely on the plantations good intentions for this aspect

“The Forest Stewardship Council (FSC) is an independent, not for profit, non-government (….), that provides standard setting, trademark

assurance and accreditation services for companies and organisations interested in responsible forestry

ounded in 1993, FSCs mission is to promote environmentally appropriate, socially beneficial and economically viable management of the worlds forests (…)

The distinctive FSC trademark - the check and tree symbol - as well as

the letters FSC and words 'Forest Stewardship Council' enable customers

to recognize responsible forestry products in stores around the world

Major retailers in Europe, North America, South America and Asia ask for FSC certification when ordering forest products so they can assure their customers about the origin of the products they are buying.”

(www.fsc.org dec 2004)

As similar certification for bamboo, by an non-partisan, independent

organization, assuring customers that the management of the plantation resembles a balanced ecosystem, will be beneficial for the local populations, global ecology and marketability of bamboo Since certified wood can earn a LEED credits, if there would be a bamboo certification this would,

presumably, count towards the same credit

3 BAMBOO CONSTRUCTION MATERIALS

The majority of houses in the USA, some industrial construction and mostly all interior partitions are made with stud walls Invented in 1833: “Partially

a result of the incipient industrialization occurring in the young nation, the balloon frame was based on much lighter precut two-by-four-inch studs positioned sixteen inches apart and held together by factory-produced nails Although light, the frame was very strong and able to withstand heavy

winds, since the stress was spread over a large number of studs The factory production of nails and mill cutting of standardized lumber reduced costs and increased availability of materials to individual builders These houses were constructed quickly and easily, requiring only two workers using basic carpentry techniques The method allowed many urban workers in America

to build their own homes, in contrast to Europe where traditional

construction techniques kept the rates of homeownership low for most of the nineteenth century.(… ) Balloon-frame construction has persisted, with most homes today, whether stucco, wood, stone, or brick (exterior,sic),

based on this method (college.hmco.com, dec 2004)

The balloon/stud frame house could be a starting point of this investigation Beside studs, beams and rafters in this construction typology, also the

interior sheathing and exterior bracing could be replaced by a bamboo

based product (paragraph 0) The next opportunity is the exterior

sheathing/wall, of which the possibilities are described in 0 After which possibilities for more engineered wood based product are then investigated the same paragraph Of course there are more building components that can be made from bamboo, which are listed in 0 The overall practical

question in this chapter was: What bamboo materials could be designed, that could replace these materials and have the most practical and

sustainable properties, so that the substantial and expanding USA

construction market can be effectively penetrated?

3.1 Dimensional lumber replacement

“Dimensional lumber refers to the wood used in constructing the wall, floor and roof framing of a house” (www.greenbuilder.com, dec 2004) or any

building The dimensions that the wood and metal elements are produced in are essentially the standard components that all contractors and architects use The professions are so familiar with these sizes (in wood and steel) that all new products introduced on the market will have to conform to them (note: Europe has a slightly different set of standard sizes) In Figure 7 these sizes are listed, the nominal size is the common name, followed by actual size in inches and in MM

Nominal sizes Actual sizes Size in MM

38x184 38x235 38x286 89x89

38x38 38x63 38x89 38x140

Figure 7 Size of dimensional wood in the USA

As stick (or balloon-/metal-) framing is the most common construction method in the USA, introducing bamboo product that can replace the

common product (a 2x4), could create an enormous market potential

Bamboo could potentially be the base material for both studs, beams and rafters

3.2 Studs

The enormous market of 2x4 (and 2x6) wood/metal studs is focus of this investigation What properties does the product have to have to be

successfully introduced in the USA? And how those properties can be

optimized in the design This research is based on an investigation that looks both at copying wood and steel studs Their properties, means and methods of construction etc after which will be concluded what the most promising is

3.2.1 Wood

As mentioned earlier in this chapter, the wooden 2x4 is the most common wood size, and is used extensively for both structural walls (of homes and low rise buildings) as for interiors (homes and offices) What would be the options to replace this material with a solid bamboo stud (SBS)?

The first thought that comes to mind is making a SBSs from strips of

bamboo (similar to plyboo construction) One opportunity could be, to be competitive with pine (which is grown and dried so rapidly, to keep costs down, that it warps), to ensure the solid bamboo stud is straight, As it is mechanically produced, this shouldn’t be a big problem This would give it

an competitive edge over pine wood

Other considerations would then be:

• The use and construction would be exactly similar to wood A concern here is that the studs are generally nailed together with a nail-gun

The brute force will most likely to split the SBS (as that it is one of its properties), which will ruin the connection

• Costs (as with plyboo) probably the material won’t be cost competitive with pine (cost in chapter 4)

• Costly aesthetically pleasing material will be hidden in wall

The density (www.simetric.co.uk) of pine wood is around 530 kg/m3 (34 lbs/cf), bamboo is lighter around 300-400 kg/m3 (18-26 34 lbs/cf) This is before processing, which will add substantial weight One can make the assumption that the addition of glue and pressing the material will weigh down the material to 600 kg/m3 (38 lbs/cf) (P.van der Lugt, 2003) Making the bamboo studs 1.2 times heavier than the regularly used pine wood SBS being 20% heavier is a mayor disadvantage, which will seriously limit the market potential for this product, while most wood is hand carried on the construction site before installation this will material will put a bigger strain

on the labor force (and transportation costs) Also, since the overall

construction will be heavier, this will lead to certain structural ‘upgrades’, that will drive up the costs of the construction As this construction market

is highly competitive on price, both these factors are really unfavorable towards solid bamboo stud development

One can conclude that the hardness, its splitting properties when nailed, in combination with its greater density are such unfavorable properties, that it

is not likely that the sustainable properties will offset this If there are ways

to use the higher (softer/lighter) parts of the culm to produce these solid studs, that don’t have these disadvantages and could be nailed Such a SBS product will have potential to be successfully introduced in the US

Certainly because the construction trades don’t have to learn new

construction methods Present production process don’t allow this

‘advantages’ only SBS to be developed any time soon in my opinion Hence,

as the basic SBS has to many disadvantages, research has to focus on a lighter, an practical way to build with bamboo studs

3.2.2 Steel

Although traditionally all houses were built with wooden studs, a quick investigation of steel studs walls shows, that some light industrial buildings use this material, but its largest use is interior walls in high rise residential and office buildings in dense cities like New York They have certain

advantages I would like to address in this research “Because of the strength advantage produced by this bending process, steel framing material has a strength-to-weight ratio that is very favorable when compared to most other materials, particularly wood” (Waite, 1994) This makes it easy to carry them around on building sites and hoisting them up to higher floors

Furthermore, no sawdust is created when they are cut to size, which keeps the jobsite cleaner, a big concern when there are neighbors close by

“The gauge or thickness of sheet steel ranges from 10 to 25 By convention the higher the gauge number the thinner the steel The more light-weight

non-load-bearing interior walls of residential structures are usually made of

25 gauge steel, while the exterior load-bearing steel studs are usually built from stronger 18 or 20 gauge steel (asceditor.unl.edu, dec 2004) The

problem being with these interior (25 gauge) studs is, that they are so thin that they tend to get damaged during construction, before sheetrock is

placed The replacement of studs and occasional crooked walls this causes

is one of the inconveniences of construction typology

Weirton Steel Corporation (1995) advertises several advantages of steel Steel components weigh 60% less than wood A 2000 square foot home

requires only 6 tons of steel compared to 20 tons of lumber Also steel

components generate minimal waste and all light gauge steel construction materials are 100% recyclable On the contrary, steel’s biggest disadvantage

is its excellent thermal conductivity, making extra (exterior) insulation a crucial need if one wants to build sustainable

3.2.3 U-shaped Bamboo studs walls (Steel stud like)

The greater density of metal 7850 kg/m3 (490 lbs/cf) is compensated by its efficient 25 gage U-shaped stud design These studs have openings in their members, to save weight, but also to allow electrical conduit to be passed through them without alterations (wood studs require drilled holes on site for these measures)

If one could develop and produce a bamboo-based product that has this same efficiency and is installed in a similar fashion, this product would combine certain advantages of wood (better thermal conductivity, wood like modification) with steels (light, conduit openings), it would be a great

replacement of both products and thus have an enormous market potential

As a starting point bamboo mat-corrugated board (BMB) was examined To make this product ”platens having approximated sinusoidal wave patterns were designed to be fitted with hydraulic hot press to produce corrugated sheets by using bamboo mat coated with suitable resin binder Extensive experiments were carried out using woven bamboo mats of Melaconna

bambusoides & Ochlandra travancorica that were dipped in phenol

formaldehyde resin and pressed under temperature and pressure”

(www.bambocomposites.com, dec 2004) (see Figure 8)

Figure 8 Corrugated bamboo mat boards (www.bamboocomposites.com)

These mats are made from the higher part of the culm, that is more flexible and cannot be used for bamboo flooring and plyboo Using the higher part of the clum, that is otherwise underutilized, eg burned for heat or wasted, increases the efficiency of bamboo plantations/harvesting and processing Especially since only the lower 4m of the culm of the Chinese bamboos is used for plyboo/floors (P van de Lugt, per e-mail) Hence this would be a very useful application to use the upper part (mayority) of the plant for

bamboo-based studs

Since these mats are flexible and can be pressed into a certain shape, I think it is feasible to make a U-shape (metal like) stud, that conforms to the standard 2x4 size (See Figure 9)

Figure 9 U-shaped bamboo stud (FKB)

The studs have 5 cm (2” ) diameter holes drilled in them to enable conduit

to be passed through This also save somewhat on transportation costs and lessens thermal conductivity (that was already better than steel)

Production Bamboo is sliced into designated thicknesses and weaved into mats, as is usual in BMB production The only difference is the press that is used has

‘sharper’ corners than a regular corrugated press (see Figure 10 and the drawing on the next page)

Figure 10 Corrugated BMB press ( www.bamboocomposites.com oct 2005)

The pressed form results in a corrugated board (assumed 3mm thick) with right (radius 3-5 mm) corners This is has to be determined by testing, the sharper the fold, the stronger it will make the material and the tighter the connections between the studs can be

After it is pressed the edge of BMB are trimmed off and sliced in half

(horizontally) Woven sheets will must be 10’ 3050 mm high The width depends on the used machinery, which will determine the number (and size)

of the ‘2x4’ U-shaped bamboo studs (UBS) that are produced

A variety of sizes could potentially be made from with the same press, when

fitted with different size press elements The use for this is of course the

different sizing demands of the construction industry, but there is also a need for slight width variations, which will be explained in the next

paragraph

Figure 11 3-D view of UBS stud configuration (FKB)

Connections for U-shaped bamboo studs

Just as one can assume SBSs have splitting problems with nails, a different connection problem occurs with UBSs When compared to metal stud walls system, which has slightly wider runner tracks (1mm) that can receive the studs, allowing easy installation with screws A different solution has to be found for UBS, which will be strong, efficient and quick

When on considers that the thickness of the bamboo stud has to be at least 3mm (1/8”) then one can understand that the horizontal elements

(runner/header) have to be able to receive the stud, meaning they will be just as wide on their interior, as the regular UBS is on its exterior (see

Figure 11) So to compensate for the 3mm thickness of UBS material on both sides, the UBS-runner has to be 6mm wider to be able to receive the stud

The last problem that has to be solved is how one connects the stud to the track

Connecting UBS to runners with screws

“(…) considering how easily bamboo splits and how

difficult it is to glue it Perhaps we need to find suitable fasteners

and methods for making connections Perhaps screws can be

engineered for the singular purpose of holding bamboo screws that bite into bamboo, but which will nonetheless require pilot holes to avoid splitting Fine threaded screws tend to strip out a hole in bamboo quite readily Perhaps a course threaded screw would be more effective, such

as drywall screws” (groups.yahoo.com oct 2005)

Connecting the runners to the floor can be achieved by pre-drilling holes, and screwing them to the floors or concrete nailing them with a nail gun with a washer The biggest concern is the screwed connection from runner

to studs, as this is the majority of connections that will be made If the UBS can be screwed into without splitting it, so that the screw will make a decent connection, that would be the easiest way to solve this problem Otherwise the pre-drilling would present a, time consuming and costly, alternative This is unfavorable from an economic point of view and is preferably avoided

The woven BMB properties, being multidirectional (several layers of mat), will decrease the likeliness of the material splitting This has to be

researched on actual prototypes of the UBS system, which will determine if the screws will split/restrict the connection, or that it is economically (time-wise) feasible to pre-drill holes for this connection

Connecting panels to the UBS and runners