INDEX
U1 – INTRODUCTION
U1 TIME
PAGE
U1 Learning Outcomes
5
U1 Session 1 : General Introduction 4 hr Info-Presentation 1 : History of Straw Bale Buildings Info-Presentation 2: Modern Straw Bale Buildings &Trends
6 7 8
U1 Session 2: StrawTalk 1 day Info 1 : Straw and Bale Properties Tips: Straw Bales – Quality, Density, Measurements, Expansion Info 2: Storage Info 3: Straw Bale Production Info 4: Safety on the Building Site Tips: Safety – Ladders & Scaffolding, Slip- and Fire Hazard, Lack of Attention, Pikes
10 11 12 16 17 18 20
U1 Session 3: Testing and Customizing Straw Bales 1 day Info 1 : Handling and Adjustment of Straw Bales Tip: Carry Straw Bales and save Energy Info 2: Cords and knots Tips: Tools – Belts, Hammers, Cutting, Sawing, Knives, Hedge Saw, Motor Saw, Persuader, Rake, Bigbags, Bale Needles, otherTools, filling Aids (Boards), Stuffer, Surface Shaving/Smoothing, Filling Gaps and Cavities
27 28 29 30 31
Credits and Impress
48
SHORT VERSION OF THEFull STEP HANDBOOK U1 Version is available only in the STEP-Training
3
U1 – INTRODUCTION
LEARNING OUTCOME
U1 Level 3 (ECVET credit points: 1 5) / Level 4 (10)
Knowledge
Skills
Trainees know … • various types of straw and their usability • history of straw bale building • the properties of a good construction bale (moisture, • direction and length of fibres, dimensions, density, amount of weeds, type of twine) • about the production techniques of straw bales • the health and safety regulations related to straw (fire hazard, dust, slipping) • recommendations for the farmer in the production of good quality and good bales • how to handle, divide, shape and store straw bales • appropriate tools for straw bale building (measuring, shaping, compressing and handling) • the appropriate ways of shortening straw bales • reutilisation of remaining waste material
Trainees can … • define the quality and properties of building bales (dimensions, humidity, weight, density) • define the amount of weed and the direction of the fibres • plan and supply of materials • adjust the shape of the bale and cut them accurately to size • divide and compress the bales • use the tools for handling and transforming straw bales according to security rules • keep the bales dry and well ventilated during storage and transport
Competence Trainees can … • organise appropriate bales and skilfully work with bales (transport, storage, handling) • estimate the risks connected to the use of straw and knows how to avoid these risks • communicate with the other players on the straw bale building site about necessary safety measures • work in teams
5
SESSION PLAN S1
U1 – INTRODUCTION
U1
Session Plan U1-S1 : General Introduction Objectives:
Good start of training: It’s important that the trainees feel comfortable. The trainer has to create a good atmosphere. Introduction of participants. The advantages of straw bales in sustainable building Communicate with the other players Work in team
Methods:
- Energizer to know each other better (game) - Lecture/Talk - Practice - Power point
History of straw bale building
Theory
Examples of professional straw building
Practice
First contact with straw bales (free style)
Trainer:
Place:
Classroom Workshop
Duration:
Min. 2 hours
Equipment:
Projektor Flip chart 50 Straw Bales Anything else you need for games
Documents:
Trainer Sheet: Tr1 Games Tr2 SheetTrainee Tr3Training programme Tr4 Free style Tr5Why Straw?
Text sheet:
Tx1 Ecological Advantages
Powerpoint:
Ppt1 : History of Straw Bale Buildings Ppt2: New Buildings
Evaluation:
Multiple Choice
Organisation:
One month before order 50 bales
6
U1 – INTRODUCTION
History of Straw Bale Building
SESSION PLAN S1 – INFO-PRESENTATION 1
U1
7
U1 – INTRODUCTION
SESSION PLAN S1 – INFO-PRESENTATION 2
Modern Straw Bale Buildings &Trends
8
U1
SESSION PLAN S2
U1 – INTRODUCTION
U1
Session Plan U1-S2: StrawTalk Objectives:
Know various types of straw and how it differs from hay The properties of a good construction bale (moisture, direction of fibres, dimensions, density, content of cereal, type of string, shape) About the production techniques of straw bales The health and safety regulations (fire hazard, dust, slipping) Recommendations for the farmer in the production of good quality and good bales Keep the bales dry and well ventilated during storage Health / allergy
Methods:
Practice
Theory
Lecture / talk Practice Power point Quality control (e.g. impurity: other plants or stones inside?) Handling the bales preserving the good shape Properties in different directions Insulation value / vapour resistance Requirements for good building straw bales Baling machines Maintenance of machine / different kinds of harvesting and bailing machines / good use of regulation of machine / different twines Before the straw talk: talks about different types of cereal (length, colour, strength, see the wax protecting the straw, discover that the stalks are empty, etc.) Prepare two bales, one ideal construction bale, another in bad condition (increasing the bad conditions). The trainees discuss and discover the differences before the straw talk.
Organisation:
Trainer:
Place:
Class
Duration:
Min. 2 hours
Equipment:
Projector Flip chart Straw bales in different conditions Different grains Simulated working place
Documents:
Info sheet: i1 straw (bale) properties i2 storage i3 straw bale production / baling machines i4 health & safety Text sheet: Tx1 manual baling machine Tx2 the best bale (ASBN) Tx3 list of humidity measure
Powerpoint:
Ppt1 : the best bale
Evaluation:
Multiple choice
Prepare classroom. Have different types grains talks. Two bales, prepare one in a bad condition (bad shape, high humidity, bad colour, low density, strings removed, with cereal, with herbs, short straw, etc.) and another ideal bale.
10
U1 – INTRODUCTION
Properties of Straw and Bales
SESSION PLAN S2 – INFO 1
U1
11
U1 – INTRODUCTION
TIPS S2 STRAW BALE – QUALITY
U1
001 To check the Quality of Straw Bales
If you want to use your own bales locally and you do not want to use certified bales (specified as a building material, ETA), you have to check the quality of the bales and therefore the suitability as building bales. The ideal bale is 1 ) yellow (and not gray, brown or black), 2) form stable (similar to a cuboid rather than a ball), 3) dry (content of moisture not over 1 4%, if a bale is yellow, it has never been in contact with moist for long periods), 4) from hard cereal cultivars (winter or summer wheat, rye or spelt), 5). free from green grains (less than 2% by weight), 6) sufficiently dense (851 20 kg / m3, which gives a weight between 1 2 and 1 7 kg for a standard small bale (80 x 47 x 36)). If the material is from organic cereals or conventional cultivation is far less relevant in comparison with the residual content of pollutants (pesticides) in the constructional bales, as e.g. from stalk shorteners (in rainy areas almost already standard). Biologically cultivated grain often has the disadvantage that the amount of greens is higher. And with moisture (imagine the moisture-content of the plaster on the straw), the weed acts as a catalyst for mold grow.
12
U1 – INTRODUCTION
TIPS S2 STRAW BALE – DENSITY
U2
002 To check the Density of Straw Bales
In order to determine the density of the bales, and thus their suitability as building bales, the weight can of course be measured (hanging scale, put on bathroom scale with and without bales...). We know from tests that the bale's best insulation values are between 90 and 1 40 kg / m3. Below and above, it decreases slightly (too much air in the bale means convection, too little air means less insulation, because the stationary air between the stems provides the good insulation value). Now you can calculate: approx. 7.5 bales fit in 1 m3, the measured weight x 7.5 = the specific density (kg / m3). It is easier and quicker to try to press the two cords together. If this is easy the bale is badly compressed, if it is hard, the bale has its ideal weight and if it doesn't go at all ... usually it is not possible to bale higher densities with the small standard baling machines. Higher densities are not necessary, when we have to cover/plank (boards) the straw bale wall on both sides. For this kind of construction, lighter bales (85-90 kg / m3) are more suitable, as it is easier to work with it. But it is important to have an appropriate density of min. 100 kg / m3 (with 36 x 47 x 80 cm bales, ie 1 3.5 kg / bale), when the wall is directly plastered.
13
U1 – INTRODUCTION
TIPS S2 STRAW BALE – MEASURING
U2
003 Measuring Straw Bales It sounds simple, but often leads to confusion or at least to communication difficulties. How long is a bale really? Where do you measure exactly? Because of rounded edges or bulged side surfaces, one person comes to 87 and the next to 80 cm. And why is it so important at all? Well, in the ideal case (if we have a wall without windows and doors), we assemble the posts naturally in a distance according to the length of the bales. Since the lengths vary slightly, we take the measurement from the longer bales and fill too short bales with flakes (01 6). The easiest and most reliable method of measurement is to flatten the sides of the bales. If the bales are now semi-rectangular, we hold 2 boards or plates on the side of the bale and measure the distance between them. If measuring this way, a 87 cm long bale will fit between a 85 cm post spacing. The measure of the thickness is usually 36 cm (but also worth checking). We have already had to extend roof rafters of 35 cm, because the roof plate could not be mounted on the protruding bales. And the width is in most cases 47 cm (and not 50, as often published). Again, it helps to measure between two boards. We can at least be sure that the thickness and width once measured in a charge is the same for all other bales (if it comes from the same baling machine). And one more thing: the boards must of course be kept parallel for exact dimensions.
14
U1 – INTRODUCTION
TIPS S2 STRAW BALE – EXPANSION
U2
004 Straw Bales expand only in press-direction (of bale canal)
Straw bales always (and only) expand in the longitudinal direction, ie, in the direction in which they have been compressed in the bale channel to so-called (8-1 4 cm thick) "flakes" (layers). These pressure-forces in the bale should be used: if you cut the cords after filling them in post and beam constructions, good compressed bales close the gaps to the construction (and you have less to stuff). That is why we always cut the strings in wooden p&b constructions. However, the bales will not expand more than 2-3 cm. For larger cavities, we fill flakes into the spaces (tip 01 6-01 7). Only in the load bearing straw bale construction the cords remain in the construction, otherwise the walls would fall apart after removal of the temporary construction.
15
U1 – INTRODUCTION
Storage of Straw Bales
16
SESSION PLAN S2 – INFO 2
U1
U1 – INTRODUCTION
SESSION PLAN S2 – INFO 3
U1 Production of Straw Bales (Baling)
17
U1 – INTRODUCTION
Health and Safety at the Straw Bale Building Site
UNIT S2 – INFO 4
U1
Objective: To observe safe working practices at all times - and to have fun!
Good practices In general, there are fewer accidents and errors on the site if everyone is happy and well motivated. It is good practice for the entire team to get to know each other, and how each separate action is part of the final realization. It is very useful for everybody to meet at the beginning and at the end of each day, to share thoughts and reflections on the work to be done or the way to do this, and to discuss potential problems. If we can recognize our interdependence with each other rather than be in competition, which will help to generate a staff attentive and helpful, or each individual is responsible for his own person, but also takes into account the well-being of others. This is particularly necessary at a site self-construction or the people have different levels of knowledge or skill. Encourage the questions concerning a task or a tool, until everyone feels comfortable and safe in their use. The construction sites in bales of straw are renowned for their ethics to work together, share the knowledge and skills, equality for women, the learning enjoyable and fun. And there is no reason that these qualities cannot be encouraged on all construction sites.
Security on the site These are the basic guidelines that will help to ensure that no person suffers an accident: • Each construction site, even if it is your own home, should have a first aid kit available and everyone must know where it is! • Never use defective tools!! • It is forbidden to smoke anywhere on the site or around the straw stored. • Make sure that you know where is the nearest water point. • Always keep the site clean. The scaffolding and working areas must be swept and tidied up each evening. It is useful to store materials and waste etc in specific locations to maintain the order on the yard. • Keep a central place for tools so that all those who are not used can be delivered, and can be found in case of need. • Never leave the tools lying around. Each person should be responsible for the tools he or she uses, must know where they are and where to store them when they are not used. • Unplug all electrical tools when they are not used! • Don’t let electrical wires become trip hazards on the site! • Fuel for the chainsaw or the brushcutter must be stored in a locked space far from the straw. • All scaffoldings must be firmly attached. • Step ladders and work platforms must always have a solid foundation. •The helmets should always be worn. Especially so when somebody works above oneself. • Extra precautions should be taken in the use of heat or open flame. Never use anything like that in the vicinity of exposed straw.
18
U1 – INTRODUCTION
Health and Safety at the Straw Bale Building Site
UNIT S2 – INFO 4
U1
Tools for the construction with straw bales The construction in bales of straw requires almost no specialized tools. As with most things, there are different grades of tools on the market. Generally speaking, it is better to buy tools of good quality, even if they cost a little more, because the tools of poor quality may be inaccurate and wear quickly. They will certainly frustrate you and make you feel incompetent. Remember, the tools are the means by which you are able to do a good job. You will use them for a long period, therefore take care of it, sharpen it, oil it, whatever is necessary to have it in good shape. They must resist the normal wear on a building site, therefore need to be robust. The right tools, if they are properly maintained, can last a lifetime, not only for the time you build your first home. The right tools make the job easier, faster, and more secure. Watch the security notice for each tool!
Clothing and safety equipment When you work with straw, it is advisable to wear a long-sleeved shirt and long pants, because the stalks of straw can be thorny. Gloves are also a must, at least for some aspects of the work. Eye protection, ear protection and dust masks may be necessary for some work. The helmets must be worn if someone workes above yourself. Safety shoes are necessary for protecting the feet from falling objects. Identify the responders qualified on the site, and attach a list of emergency phone numbers.
19
U1 – INTRODUCTION
TIPS S2 SAFETY – FALLING
U1
005 Safety on Straw Building Sites: Falling (from) Ladders
When filling from a stepladder, always place the steps parallel to the wall, otherwise there is the danger that you will fall over from the ladder when filling with high pressure. The distance of the ladder to the wall is also important for the pressure and your power. The more the you use your own weight as pressure, the less efforts and muscles are required for the filling process. So, try to place the ladder a little further from the wall, and lean your body in an angle to the wall. Do the same with auxiliary scaffoldings (scaffoldings with planks) and the façade scaffolding (you will nedd a space between also for stuffing and plastering). Finally, leaned ladders should be fixed with a cord or a wire at the upper end, if there is a risk of slipping (especially on straw) as well as falling danger.
20
U1 – INTRODUCTION
TIPS S2 SAFETY – SLIPPING
U1
006 Safety on Straw Building Sites: Slipping
Where work is done, chips fall. In our case, it is straw. Summerized - scaffoldings, floors, ladders and stairways on our construction site are soon covered by a (thin) layer of loose straw. As romantic as this may be: loose straw is quite slippery (especially when wet, ie while plastered). Cables disappear under this straw blanket, as well as tools and, of course, holes (e.g., between provisional planks or boards). The most important danger, however, is represented by our hardboards for filling (023). Loose straw in combination with (the slippery) filling aids laid flat on the ground will let you slip even with the best shoes. The first requirement on a straw site (also for reasons of fire protection) is therefore cleaning: collect the loose straw in BigBags. Tools should never be placed on the ground (always collect them centered on tables - easy available for all employees. Place the cut bales on the narrow side and lean against a wall so that the layers do not fall apart. And before the shaving, all the straw is collected again. Because the short straw which is falling from the walls when shaving is ideal as a fiber reinforcement for our plaster.
21
U1 – INTRODUCTION
TIPS S2 SAFETY – FIRE
U1
007 Safety on Straw Building Sites: Fire
The handling with open fire on a straw site is, of course, forbidden. This applies both to smoking and especially to welding and hot-tacking (whether it is gluing roofing paper or welding rainwater gutters). Here, great caution is necessary, because most of the fires were caused by the flames or heat of roofing works or improper - non insulated - chimneys through straw bale walls. Finally, waxed or oil-impregnated cloths must be kept in sheet metal (danger of self-ignition). Nevertheless: Well compressed straw bales form a coal layer in the event of fire, which strongly hinders the propagation of the fire (see fire test below). The problem is loose straw, which literally burns like tinder ("straw fire").
22
U1 – INTRODUCTION
TIPS S2 SAFETY – CARELESSNESS
U1
008 Safety on Straw Building Sites: Carelessness
Everyone who works on a straw bale building site should be aware that one can barely see the ground with one or two straw bales in their hands. The ground on which we move, - whether it is the loamy excavation pit, a foamed glass fleece covered with straw (which perhaps is folded), the unfinished floor, 2 laid boards for a ramp (always the same thickness), a temporarily planked (interleaving) floor or terrace (no holes, planks fixed with screws) or the scaffolding (well anchored), - should be blindly accessible without being seriously injured. Often we work with large weights (wheelbarrow full of clay). We should be at least able to rely on the safe ground under our feet. Laying planks without temporarily fixing them (nailing, screwing) is negligent. To remove a scaffolding plank somewhere without an arrangement, because youI need it somewhere else, is actually a murder attempt. It is also negligent not to anchor a scaffolding to the wall. And finally, anyone who runs or jumps on a construction site should get the red card, no matter how fast he / she wants to finish the work.
23
U1 – INTRODUCTION
TIPS S2 SAFETY – PROTRUDING TIPS
U1
009 Safety on Straw Building Sites: protruding Tips
Especially when nailing or shooting brackets you will not always hit the wood-construction behind. The tips of the brackets / nails / screws extending in the insulation area are difficult to see when filling, so always check and remove or flatten them before you strat the infill. They are a serious risk of injury. When naileg / screwed planks are removed, remove the nails / screws immediately (if necessary with the grinding machine). Even with steel caps on the shoes the kick on a screw tip is dangerous (and hurts badly). Even building irons (rebars), which extend the foundations, should always be made more visible with a cup or bottle. Summarized it can be said that most of the subsequent accidents occur under time pressure / during busy work. It should be self-evident that we can rely on the correct execution of the work of our partners and those, who worked before us, that everybody corrects his/her own mistakes.
24
U1 – INTRODUCTION
TIPS S2 SAFETY – CABLES & ACCUS
U1
010 Safety on Straw Building Sites: Cables and Accus (Batteries)
The cable-free construction site will remain a dream, despite batteries (accus). Compressors and many other tools have electric cables. Cable drums and their feeds usually run crosswise through construction sites and where barriers are piling up (wooden stacks, straw bales) also cross these piles on top. And even batteries are charged via chargers with cables. Cables, hidden under the straw on the ground or on scaffolding, can easily become a tripping trap. If you are in a hurry on a construction site, you are more exposed to the risk of serious injury. In case of shaving the bales with hedge saws or cutting with the alligator (electrical saw) you can if you are not careful and wear the cable for example over the shoulder - also slightly cut the cable and cause a short circuit (or ruin the tool).
25
SESSION PLAN S3
U1 – INTRODUCTION
U1
Session Plan U1-S3: Customizing Straw Bales Objectives:
How to handle, divide and shape straw bales Appropriate tools The advantages and disadvantages of different types of strings The appropriate ways of tying straw bales (knots) Check the quality and usability of straw bales
Methods:
Practice
Theory
Presentation Testing and customizing straw bales
Trainer:
Place:
Workshop
Duration:
Min. 3.5 hours
Equipment:
Tools and straw bales
Overview about the tools on a typical straw bale building site Methods of measuring and manipulating straw bales (tools, machines)
Documents:
Plan the supply of straw bales Use the bale in the correct orientation Measure the bales Adjust the shape of the bale and square off the ends Divide and restring the bale Cut the bale Calculate the density of bale Check/measure moisture in the bale Use tools for handling and transforming bales
Evaluation:
Trainer sheet: Tr1 Health/ Safety game Info sheet: i1 Control sheet i2 handle and shape bales i3 twine and knots i4 straw bale measuring
Multiple choice
Organisation:
prepare the work shop (tools, bales, safety recommendations)
27
U1 – INTRODUCTION
Shaping Straw Bales
28
SESSION PLAN S3 – INFO 1
U1
U1 – INTRODUCTION
TIPS S3 HANDLING STRAW BALES
U1
011 Carry Straw Bales and save Energy
Small standard straw bales (36 x 47 x 80-100 cm) are usually tied with 2 strings in the longitudinal direction (formerly sisal, now mostly polyethylene). In order to carry the straw bales, these cords are of course very suitable. However, always put the hand around both strings when carrying, so that a cord does not slip from the bale (which - at least if the bale is not perfectly compressed - causes it to fall apart). Keep the weight of the bales (approx. 1 2-1 4 kg) as close to the body as possible, it reduces the force required. Another possibility is to embrace the bales and to carry them close to the body. This can be a relieve for our fingers, because the cords cut with time quite nicely into the hands. In addition, you should quickly learn to see the raw material bales as a valuable material and not as a favorable waste material in grain harvesting. Watch out for the mountains of loose straw, which can occur if you do not care about this building material. It is quite elaborate to dispose, even if it can finally be composted and it is always in the way on a construction site.
29
U1 – INTRODUCTION
Cords and Knots
30
SESSION PLAN S3 – INFO 2
U1
U1 – INTRODUCTION
TIPS S3 TOOLS – BELT & BAGS
U1
01 2 Straw Bale-Tools: The practical Belt
I personally have in my (carpenter-)belt bags (left and right) always my two stuffers (like colts), for me the most important professional tool in straw bale building, next to a knife to cut the strings. In the bags I have a few galvanized 6 cm nails, various screws, a meter measure and a carpenter's pencil. Also gloves which are thin enough not to prevent the feeling in your fingers, but protect you against the many small chips from the construction wood. Actually, the bags should have top tabs, as they are constantly filling with straw. Or I would have to turn the bags to the backside, but I find that not practical looking for right screws or bits.
31
U1 – INTRODUCTION
TIPS S3 TOOLS – HAMMERING
U1
01 3 Straw Bale-Tools: Hammering Nails
The Carpenter-Hammer must not be missing. With it, you simply (no, that is actually a lie) pull out nails. There are two different models available on the market: those with the flat tips, which are also ribbed so that they have better grip on the nail head. And a model (claw hammer) that often meets me in other countries, which I personally can not handle. It is so bent and has such a round head that it is almost impossible to get a nail straight in. What I want to say is, that everyone is used to the tool with which he has learned. That is why you should always take it with you to your building sites. Even with hammers without grip on the cap, it can be hard to strike a nail straight. No wonder, that nailing seems to be the biggest challenge for many in straw bale building. Therefore, here are a few tips: 1 ) Holding the hand at the bottom of the stem, helps to save energy. It is about the momentum, and the less often a nail is hit, the less chance of bending it. Well, practice makes perfect. 2) Look at the hammer head and align it before impact so that it does not strike obliquely on the nail head, avoiding the distorted bending and pulling out again. The same technique also leads to the goal (hole) with tennis or Minigolf.
32
U1 – INTRODUCTION
TIPS S3 TOOLS – CUTTING
U1
01 4 Straw Bale-Tools: Cutting Straw Bales
II tried pretty much everything that has blades. But the only tool that really cuts straw like butter is the electric saw (in German Elektro-Fuchsschwanz). I use the Bosch ® Professional with 35 cm sword, which also cuts at the top. There are alligators with comparatively long swords. But if the first 5 cm of the tip do not cut (see drawing below), it becomes tedious. It is not always a question of dividing or cutting a bale in the longitudinal direction, but sometimes also of forming a wedge or an opening (niche) into the bale. The two blades are, by the way, easily interchangeable and there are different ones for wood (and straw), metal and plastic.
33
U1 – INTRODUCTION
TIPS S3 TOOLS – SAWS
U1
01 5 Straw Bale-Tools: other Saws
In addition to this all-purpose device, a simple (sharp) hand saw (without electrics), e.g. for the cutting of our CUT-battens should of course be available. Also a jigsaw is a nice addition to our tools, especially for all round cuts. But this is more for wood construction, as it usually don't cut a straw bale. A crosscut saw is, of course, also worth the gold on a construction site, for all exact cuts in the wood (joining). And finally we need a table circular saw, if we e.g. cut the battens lengthwise from the raw planks.
34
U1 – INTRODUCTION
TIPS S3 TOOLS – KNIFES
U1
01 6 Straw Bale-Tools: Knifes (Cutters)
The advantage of cut-off blades is that they are always sharp. As we soon get muscles when working on building sites we start to cut with more pressure, so the more sturdy 3 cm blades are more convenient to us. The 1 cm toy blades are good enough for paper, but even do hard when cutting the polyethylene cords. By chance, cutting straw bales on a construction site (actually more sawing) with a new, ribbed bread knife works wonderful. The result was so positively convincing that I always have one with me (or ask the cook for it). For all other knives applies: it's about the sharpness, halms/stalks are quite brittle and it's boring to sharpen your knife constantly.
35
U1 – INTRODUCTION
TIPS S3 TOOLS – HEDGE SAW
U1
017 Straw Bale-Tools: Shaving Surfaces with Hedge Saws
We do not only want to squeeze a few protruding stalks with hedge saws, in most cases we want a plane surface to save plaster and to avoid different drying times, even if bales are slightly differently thick or bulged or not exactly installed plane. Even if there are customers who prefer a more organic-hunched surface, in most cases they mean slight bumps in the (hand-) plaster and not simply covering uneven bales with the plaster. The cutting of the hunches of straw bales is a long-term work, but it really becomes hard work with not really sharp hedge saws. Unfortunately sharpening is often as expensive as a new one. A tip to save energy is to pick hedge saws with a rather shorter sword (about 50-60 cm). The longer the sword, the more pressure we need to push to the bale surface, and the harder it is to shave a round wall or vault inside. In terms of strength: from 450 W, hedge trimmers are robust and strong enough. The sharpness of the knives is much more important. Hedge saws are among the very safe machines (since they cut only between the knives). Nevertheless, you can tweak neatly with hedge saws (a small cut with painful bruising is the result). It can happen when you sit on the scaffolding shaving the walls. More often, if you don't take care, you will cut the cable and cause a short circuit. Therefore, it is best to carry the cable over the shoulder. Or choose a model with battery.
36
U1 – INTRODUCTION
TIPS S3 TOOLS – CHAIN SAW
U1
018 Straw Bale-Tools: Cutting Bales with a Chain Saw
Some can do it, I have never managed to cut a straw bale with a chainsaw, it almost always leads to smoking straw halms under the chain cover in short time. The mixture with the chain saw oil is quite inflammable. The trick is to use a chain saw with rather long sword and cut only (mainly) with the tip so that the stalks fly tangentially away and do not get under the protective cover of the chain. Gasoline powered chainsaws are also noisy and stinking, electrical usually not so strong. For structural wood ideal, I cannot recommend it for straw bales from my point of view.
37
U1 – INTRODUCTION
TIPS S3 TOOLS – PERSUADER
U1
019 Straw Bale-Tools: the Straw Bale Hammer or Persuader
This wooden hammer "persuades" each bale (at least as long as it is not fixed by battens). It is a must on each straw building site and also easy to manufacture in the DIY process from residues of construction wood. Only the handle should be sturdy (typically hardwood). Do not screw the handle to the wooden plates too often (2 times should be enough), otherwise it will break more easily at this point. The Persuader should be heavy, but it is used with a swing to move the bales back into the row, or to connect the upper bale with the underlying ones well.
38
U1 – INTRODUCTION
TIPS S3 TOOLS – RAKE AND BIGBAGS
U1
020 Cleaning the Building Site: Rakes and Bigbags
Keeping your construction site always clean is not only practical, it's also a matter of safety. With a broom you will work mainly on floors, natural subsoils need flat rakes for cleaning and removing straw, as we often cleaning grassy or gravel surfaces. The elastic leaf rakes work best for this. And because of the quantities that are caused by building bales due to destroyed bales and loose straw, the purchase of BigBags is worthwhile (or you take your used clay or sand bags).
39
U1 – INTRODUCTION
TIPS S3 TOOLS – BALE NEEDLES
U1
021 Dividing Straw Bales with Bale Needles
Bale Needles may be useful or even indispensable for load-bearing straw bale walls (in this case each new row of bales needs half-bales). In the infill-technique, the bales are compressed more easily with adding flakes between two plates (023). Bales can also be compressed to a certain density by simply rebinding it with strings, depending on the strength you tear, or with screw clamps. But as bale needles are connected to straw bale building like the halms to the bale, let's look at these tools. Actually a pointed wooden stick with two holes at the top is enough for their function (since there are 2 new cords needed - one for the right, one for the left bale part). There are also combined bale needles (which are connected to a bar / handle, which pull all 4 cords through the bale at the same time (2 upper and 2 lower instead of the 2 existing cords). After you pulled your strings through the bale, the cords are knotted to each half-bale. There are special knots, as they are known from sailing. After you rebound your halfs, the original two cords are removed, thereby maintaining the density of the bale. If you took the right strings on the right half bale you can divide your bale (otherwise, if strings are crossed, you have two connected half-bales). So you can definitely say that some straw balers make a science out of a simple thing.
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U1 – INTRODUCTION
TIPS S3 TOOLS – MORE TOOLS
U1
022 More Tools on Straw Bale Building Sites
A cordless screwdriver (per worker) must not be missing on straw sites. We will not screw straw bales to the wall, but often enough we need to do smaller woodwork and fixtures, just for safety reasons. We also need a spirit level. But that's it for now. With these tools you are already equipped as a straw bale builder. Except for the crosscut saw (which is brought by the carpenter) and the table circular saw (let's assume, it is anyway on a good construction site) our tools fit playfully into a small car, even with 3 employees and luggage. Especially in the case of workshops, it is a good idea to put the tools in different labeled boxes so that they can be found by every participant. Paying attention to your collection of tools saves a lot of searching-time.
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U1 – INTRODUCTION
TIPS S3 TOOLS – INFILL AIDS
U1
023 Straw Bale-Tools: The essential Infill-Aids (Boards)
For infilling flakes, we use thin (6 mm) plates (baords) of plywood, hard fiber, plastic or metal, usually with a handle (hole) or with metal flaps with a bent folding handle, so that they can be pulled out more easily. The smooth surface shows to the flake, the rough to the existing bale or the construction. The boards should be available in different sizes (approx. 47 x 47 cm for filling from the front, 36 x 57 cm for filling from above, or half-sizes for smaller cavities).
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U1 – INTRODUCTION
TIPS S3 TOOLS – INFILL AIDS
U1
024 Straw Bale-Tools: How to handle Infill-Aids
When infilling bales or flakes (best with a helper), the boards are held like a funnel to create the largest opening possible for the position (see picture). As soon as the bale or flake is half filled into the wall, the helper pushes the plate to the bale (so that the funnel becomes a tunnel with parallel sideboards and the straw is not squeezed on the backside). Insert the flake only until the surface of the wall (same level as the adjacent bales around). Another tip: usually more flakes fit into cavities than assumed. If you fill too little, you must repeat the process. Therefore, use a little more straw (several - still cohesive - layers at a time), then the surface becomes even more even. When removing the boards, lateral wobbling helps (much easier than just pulling). If enough layers are infilled (high density) the boards are difficult to pull out: this is the guarantee for a really good plaster surface.
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U1 – INTRODUCTION
TIPS S3 TOOLS – STUFFER
U1
025 Straw Bale-Tools: DIY-Stuffer in two Sizes
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No one can fill straw bales between posts / rafters (or stack them over one another in the load bearing straw bale building) without leaving any holes at all. This is due to the fact that bales on the edges are often rounded (and not sharp-edged); on the other hand, cavities can also develop when filling (densifying) with layers. And finally it happens again and again that, for structural reasons, there is a (diagonal) squared or round wood in the insulation area, such as the planks of an intermediate vault. In order to fill these cavities with (loose) straw and prevent convection in the thermal insulation layer or simply a cold bridge, we use homemade, simple (DIY) stuffing tools. Of course, you can also stuff with the hands (fingers), but I wouldn't recommend that for larger areas. After some days you cannot move your fingers any more. Especially if the wall is to be plastered, it is important to stuff the straw in the same density as the bales nearby, so that the weight of the plaster does not pull it out again. For these purpose we need 2 tools, made of strips of 25 x 25 mm (1 x 1 ") for the small and 25 x 50 mm for the large stuffer. So we are building a "T", which we screw together 1 -2 times (6-8 cm screw, 5-6 mm hole pre-drill). The smaller handle has a length of 1 5 cm, the larger handle has a length of 25-30 cm, which we slant at the top like a screwdriver (with a jigsaw or crosscut saw). Finally, we put a small notch in the middle of the "cutting edge" so we can later better collect the straw to be stuffed. Finally we take sandpaper (or a rasp) and round off all edges easily.
U1 – INTRODUCTION
TIPS S3 TOOLS – SHAVING AND SMOOTHING
U1
026 Preparing Straw Bale Surfaces for Plasters
Straw bales provide a pretty good plaster ground when the surface is prepared (and will not be planked). To achieve the best possible and long lasting connection with the plaster, the surface of the bales is cut with a (sharp) hedge trimmer. Since this can be a lot of work (especially with well compressed bales), short hedge saws (about 60 cm of sword) are usually better than long ones. This also makes it easier to cut curved surfaces (as in the case of a round house or vault). It is not just about removing protruding stalks, but of smoothing all the unevenness, ie shortening the whole stalks one to two centimeters. On these many stalk ends, the plaster adheres much better than on the untrimmed stalks covered with a wax layer. This method of plaster preparation is much more useful than depositing the bales (so that the wax layer disappears). Earth- and lime plasters have mainly mechanically based connections to the plaster-ground through rough surfaces.
45
U1 – INTRODUCTION
TIPS S3 – STUFFING HOLES
U1
027 Customizing Straw Bales: Stuffing Holes
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Now go to the stuffing: by the rule of thumb, the loose straw is to be stuffed to the middle of the bales (about 1 8 cm deep). For preparation the surface is shaved with a hedge trimmer, then we see the holes much better. Take as many stalks as possible from a straw bale (in the beginning always twice as much as you think that fits in the hole), put this amount centrally over the hole and form a heart: with the small stuffer you insert the stalks to the centre of the bale so they are deep in the hole and only about 5 to 10 cm is exceeding. This should be done with power, and if it goes too easy, you took too little straw. The protruding stalks are then bent and put back into the cavity, this time with the larger stuffer. If we do this on both sides of the wall, a heart shape is created. It is very important that in the end the triple bent stalks neither protrude nor form a new cavity (because we have stuffed the straw too deep). The visible crease should lie exactly on the surface. We can easily remove any protruding stalks with a second hedge-trimmers (or push them by hand into the bale), but if we cut the crease, the short stalks fall out again. Why the trick with the crease? Again, we use the material's own power (the strong tendency of the stalks to expand after buckling or compression) to fix the straw well in the bale. If you do not believe, try it differently, but then you should also plaster at this place. I have often experienced that suddenly plugs of plaster fall from the wall because the straw was not well fixed in these places. This may sound a bit complicated, but it is really simple - and guarantees a perfect straw surface, which is also a good plaster-ground.
U1 – INTRODUCTION
TIPS S3 – FILLING GAPS
U1
028 Customizing Straw Bales: Filling Gaps
Larger holes and cavities can be stuffed in the same way, if necessary. In principle, we fill the gaps as good as possible with bunches of loose straw and compress the straw with the stuffer. This may seem hopeless in the beginning, but there is always the moment when everything suddenly becomes stable (and dense). One of the basic principles of straw construction is that compressed straw tends to expand and at a certain density it begins to form a stable building body no matter what shape. Straw figures or straw sculptures can also be built in this way, as hollow spaces can be filled and compressed. The only exception are oblique or very shallow cavities which have a larger opening to the exterior. Here you need to build a cage for the straw: close the surface with plates, sturdy mats (for example, bamboo) or with strips / boards, then you can stuff the straw in the cavity, without falling out again.
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STEP – Straw Bale Training for European Professionals UNIT 1 – Introduction/Einführung (201 7) Editing/Tips: Herbert Gruber, Helmuth Santler (ASBN) Cooperation: BuildStrawPro-Team (Erasmus+ Project) Design & Fotos: Herbert Gruber (ASBN, StrohNatur), More Fotos: RFCP, provided by Architects & companies. Illustrations/Icons: Michael Howlett (SBUK) This Handbook is based on the Handbook from LeonardoGroup STEP (201 5)