STEP U2 Handbook EN

1

2

U2 – INFILL AND PREFABRICATION

INDEX

U2

DURATION

PAGE

U2 Learning Outcomes 5

U2 Session 1 : Construction Systems 3 h 7

Info-Presentation 1 : Construction Systems 8

Info 2: Building Physics (Intro) 9

U2 Session 6: Construction Plan, Time Schedule 4 h 1 0

Info 1 : Design and Planning 11

U2 Session 2: Building Details 1 h 1 2

Info 1 : Building Details 1 3

Tip: 01 4 Filling Corners 1 5

U2 Session 3: Hybrid Constructions 1 day 1 6

Info 1 : CUT-Technique 1 7

Tips: CUT 1 9

001 -1 9 CUT-Technique, 002-20 CUT-System,

003-21 Structural Integrity and Bracing, 004-22 OrganiCUT

Info 2: GREB-Technique 24

U2 Session 4: Infill-Constructions 1 day 27

Info 1 : Infill-Construktions 28

Tips: Infill-Construktions 30

005-30 Adjusting Constructions to Bales, 006-31 Infill Bales: vertical

or horizontal, 007-32 Diagonal Bracing/Shear Forces, 008-33 Planking

or Direct Plaster, 009-34 Plaster as Bracing, 01 08-35 Double-Posts,

011 -36 Bowing (Buckling)

U2 Session 5: Prefab and Modules 1 day 38

Info 1 : Prefabrication 39

Tips: 40

01 2-40 Prefab-Modules in Multistorey Houses,

01 3-41 Prefab-Modules with Multibaler

U2 Session 7: Timber Constructions 4 h 42

Info 1 : Timber Constructions 43

U2 Session 8: Building Laws 2 h 45

U2 Session 9: Praxis Straw Bale, pract. Test (min) 5 days 47

Credits and Impress 48

3

4


LEARNING OUTCOME

U2

Level 3 (ECVET credit points: 20) / Level 4 (20)

Knowledge

Skills

Trainees know …

• about the existing national relevant building

regulations related to straw bale building

• the specific problems organising a straw bale

building site and their solutions (weather

protection, safety, logistics).

• the symbols to be able to understand plans

and construction drawings

• appropriate structural and wind proof

constructions to be infilled with straw

• techniques to fix the bales in the construction

• the necessity and the techniques to avoid and

to close the gaps (between bales and between

bales and construction)

• other bio sourced insulation materials, that

can be used additionally in straw bale building

• the reasons and the techniques to fill in straw

in an required density.

• the different infill- techniques and their

requirements related to schedule, planing,

budget and resources.

• about prefabrication, its specific features of

planning, its advantages and disadvantages.

•The details for the adjacent building elements

(ceiling, walls, floor- and roof plates)

• the details for openings (windows and doors)

and for intersections (chimneys, pipes, wires).

•The reasons and the techniques to prepare the

substrate with a plane and gap free surface.

.

Die Teilnehmenden können …

• control the quality ofexisting constructions

in relation to its suitability to be infilled with

straw

• handle tools and machines which are used

generally on straw bale building sites and for

simple wood constructions.

• execute different Infill construction methods

with the required compression and adjust and

fix the bales correctly.

• Fill in straw bales into prefabricated

constructions.

• implement diagonal bracing in the

construction according to static needs and

plans

• read and understand the symbolic of plans

and construction drawings

• fill the holes and gaps with straw and other

bio sourced insulation material avoiding cold

bridges

• calculate building costs related to straw bale

constructions

• prepare all surfaces for the successive crafts

people (plaster, cladding, wind- and air

tightness) or execute these these tasks in

mutual agreement.

• assemble the supporting wooden structures

and the frames for openings.

Competence

Trainees:

• can organize and attend the building site at all stages and adapt the working process, the use oftools

and adequate techniques (planning, preparations, execution, additional crafts)

• can take responsibility for the requirements ofthe performance ofstraw as insulation material.

• can co-ordinate and communicate the special needs of infill constructions with other professionals.

• can explain different techniques ofinfill and prefabrication techniques including their advantages and

disadvantages.

• Can control the general quality ofbales during the whole building process.

5

6

U2 – INFILL AND PREFAB

SESSION PLAN S1

U2

Session Plan U2-S1 : Construction Systems

Objectives:

Trainees ...

understand and are able to explain the three general different

construction-options of

a) direct-plastering (loadbearing and hybrid, NSS),

b) planking on one side (hybrid, NSS), and

c) planking on both sides (infill, SSS).

understand the needs for infilling the bales in the right density,

prevent gaps, fix the bales, direction of the halms and prevent

deformation of the construction.

know the necessity of structural bracings to withstand the shear

forces.

know and are able to explain the advantages and disadvantages of

the different techniques.

Methods:

Presentation, lecture

Trainer:

Place:

Class or workshop

Duration:

Min. 2 hours

Equipment:

Straw bales

Construction samples

Theory

Different structural options of infill and prefabrication and their

characteristics and bale requirements

Fixing bales in different techniques

Compressing bales in different systems

Advantages and disadvantages of infill and prefabrication

techniques

Details of connections: foundation, corners, windows and doors,

roof, etc.

Preparing different surfaces for plastering

Identifying the different systems in construction samples or

pictures

Documents:

Trainer sheet:

T1

Info sheet:

I1 How to choose the

construction-system,

different techniques

I2 Construction samples

Practice

Organization:

Presentation, projector, construction samples

7

U2 – INFILL AND PREFABRICATION SESSION PLAN S1 – INFO 1

Construction Systems

U2

airtight- and windproofness

only provided by plaster

diagonal bracing only through

plaster (hard to proof)

no installation area

not suitable for passive

houses

airtight- and windproofness

easier to achieve

diagonal bracing through

planking, outside: rainproof,

inside: installation area

suitable for passive houses

double safety: airtight- and

windproofness (but more

expansive)

rainproof, installation area

suitable for passive houses

8


Construction Systems

U2

9


SESSION PLAN S5

U2

Session Plan U2-S5: Construction Plan and Timetable

Objectives:

Trainees ...

have the ability to read and understand architectural plans and

construction drawings and the symbols used in.

have the ability to read and understand details of windows,

corners and connections to the roof and intermediate ceilings.

know different structural options for straw bale walls.

know the advantages and disadvantages of various solutions.

know how to make a timetable for a straw bale building site and

estimate times for infill, stuffing and wall preparation.

know about the various trades and their works and responsibilities

concerning straw bale construction (builder, carpenter, plasterer,

roofer, tin smith, window-maker, plumber, electrician,… ).

Methods:

Lecture/talk

Explanations

Practice

Trainer:

Place:

Class

Duration:

Min. 5 hours

Equipment:

Pen and paper

Calculators

Projector

Theory

Basics of architectural plans and construction drawings

Different structural options, characteristics and bale requirements

Advantages and disadvantages of different techniques

Compare the building costs (material, labour, etc.) using different

techniques

Setting up a timetable for the constructive works

Trades on a straw bale building site (who makes what)

Documents:

Trainer sheet

T1 Planning basics

T2 Characteristics of the

different construction

techniques

Info sheet

I1 Design and planning

Task

Interprete a case study comparing the results with other trainees

Draw a building detail by hand

Practice

Organization:

Prepare a case study for every group of trainees (2–3 persons), study it in order to be able

to compare it with the results of the participants.

10


From Design to Construction Plan

U2

11


SESSION PLAN S6

U2

Session Plan U2-S6: Building Details

Objectives:

Trainees ...

know the details of a wall (connections foundation-wall, wallwindow/door,

wall-ceiling, wall-corner-wall, wall-roof) for the

different infill building techniques.

can do simple non-loadbearing woodworks (install a window

frame, make a corner, make connections,… ).

can read details in plans and architectural drawings.

can detail openings in a wall (electricity, installation, ventilation,

chimney,… ).

Methods:

Lecture/talk

Explanations

Practice

Trainer:

Place:

Classroom/workshop

Duration:

Min 4 hours

Equipment:

Pen and paper

Projector

Laptops (optional)

Theory

Details of a wall (connections foundation-wall, wall-window/door,

wall-ceiling, wall-corner-wall, wall-roof) for the different infill

building techniques

Documents:

Trainer sheet

T1

Info sheets

I1 Building details

I2 Construction systems

Practice

Task

Drawing of different details of a wall (connections foundation-wall,

wall-window/door, wall-ceiling, wall-corner-wall, wall-roof) for the

different infill building techniques

Prepare (crosscut), assemble, raise and connect a sample or part

of a sample with bottom plate, ring beam, window and corner

Organization:

Plans, drawing and sampels of details

1 2

U2 – INFILL AND PREFABRICATION SESSION PLAN S6 – DETAILS – INFO 1

Building Details

U2

1 3

U2 – INFILL AND PREFABRICATION SESSION PLAN S6 – DETAILS – INFO 1

Building Details

U2

1 4


TIPS S6 BUILDING DETAILS

U2

01 4

Timber (P&B) Constructions:

Think how to fill the Corners

When designing the dimensions and making the construction plan, take care, that

there is space to infill the corners (where two walls meet). Straw bales can only be

filled into cavities between posts if they have a minimum clear width of 40 to 50 cm

(exception: flakes/parts of bales are filled). This is particularly important when a

facade is planked beforehand for diagonal bracing. Carpenters should make the

construction plan in consultation with the straw bale builder or at least have it

inspected by one. Especially in the case of wall corners, as there are a lot of simple

and practical details which have been developed in cooperation with carpenters,

structural engineers and straw bale builders and allow the easy infill and

compression of the bales in the construction.

easy infill (enough space

on both sides)

cannot be infilled

from inside

(round) corner needs a

mesh or reed-stucco

1 5


SESSION PLAN S2

U2

Session Plan U2-S2: Hybrid Constructions (NSS)

Objectives:

Trainees ...

know the different hybrid construction techniques and when to use

them.

know different structural options.

know the pros and cons of different solutions.

can organize building sites during the infill process ( i.e.: take

responsibility to leave the building site rain- and windproof, keep

strawstacks fireprotected, remove loose straw after work,… ).

can take responsibility for the requirements of straw building in a

“normal” building routine.

know the details (window, roof junction,... ) for hybrid construction

techniques.

Methods:

Lecture / talk

Practice

Explanation

Trainer:

Place:

Workshop

Duration:

Min 1 day (7 hours)

Equipment:

Wood

Screws

Straw bales

Tools

Reed stucco

Theory

Different structural options of hybrid construction techniques and

their characteristics and bale requirements

Fixing bales

Compressing bales with different systems

Advantages and disadvantages of hybrid construction techniques

Details of connections: foundation, corners, windows and doors,

roof, etc.


Viewing and study of existing building samples

Documents:

Trainer sheet:

T1

Info sheet:

I1 CUT/CST

I2 GREB

Practice

Task:

Working groups

Preparing simple wooden frames and structures

Infill straw bales in standing position (“on edge”)

Compress the bales with different techniques

Fixing the bales in the construction

Airtight/windproof connection to a window

Shaving the bales, if necessary

Preparing bales/boards for plastering

Organization:

20 straw bales for each group

Wood parts, boards and joints (screws, nails, brackets, staples) -> see material list

Tools -> see tool list

1 6


Hybrid Constructions – CUT

U2

17


Hybrid Constructions – OrganiCUT

U2

1 8


TIPS S2 – CUT

U2

001

Hybrid Constructions:

CUT-Technique

If a surface of the straw bale wall is to be directly plastered, only one side has to be

planked (and diagonally braced). Straw is a good plaster ground, wood is not.

Exposed wooden planks must be covered with a plaster ground (reed stucco, steicounder-floor,

Heraklith - magnesium-bound woodchipboard, mesh). In order to save

that labour, to save wood and improving the overall insulation value of the wall, in

some cases it’s better to just use 1 post for planking or diagonal bracing (shear/wind

forces), the other side is directly plastered. This post should not exceed 4 cm in

thickness, with a maximum width of 1 8 cm. The gap in the rest of the wall is closed

by good compressed straw bales (if well infilled). The post can be placed on one side

of the bale, facing with the straw surface (for external planking), in the middle (for

direct plastering of bales on both sides) or inside (for internal planking and

installation areas). If one side is planked, the straw filling is correspondingly easier

because the bale is simply pushed against the planks. If the post (1 " or 2,5 x 1 4 cm

for non-loadbearing, 4 x 1 4-1 8 cm for load bearing walls) is centered, you have to

take care that the bales are exactly placed near and above each other to provide a

flat surface (always look on the neighboring bales). To prevent bales from slipping

out in hybrid constructions (where they are not fixed between two boards), the bales

have to be fixed with battens: this is what we do with the so-called CUT technique.

The name comes from „Cells UnderTension“ and from cutting (because we have to

cut the bales on the surface to insert the batten).

1 9


TIPS S2 – CUT

U2

002

CUT-System:

Smart and Versatile

In the CUT-technique, on one side of the posts, a squared timber (batten) 25 x 25 mm

or 1 ” (best cut from rough, inched planks) is pressed into the surface of the straw

bales so that they are fixed in the construction and cannot slip (even when directly

plastered). For this purpose we first cut a section along the battens in the bale’s

surface (the side of the bale with the folded halms up are easier to cut than the cut

surface of the other side) with a sharp knife, grooved bread knife or electric handsaw

(two blades, Alligator). The cut is widened with your fingers or our stuffer to a

groove. Then the batten is inserted, manually with a 1 m board, which is pulled down

on each side by two helpers, with an auxiliary tool or by standing on it) and finally

fixed to the side of our CUT posts with (galvanized) 6 cm nails. For load-bearing CUT

constructions, we use posts with a cross-section of 4 x 1 6-1 8 cm (4 cm is sufficient to

keep the transversal-pressure low and to connect the boards with 2 cm of space on

both sides of the nails. Bowing of the posts is prevented by by the nails each 47-50

cm (height of the bales in a row).

The CUT technology is really a sophisticated, versatile, smart, inexpensive and yet

simple construction system that shows the straw bales at their best.

20


TIPS S2 – CUT

U2

003

CUT-Technique advanced:

Structural Integrity with Planking

A number of tests have shown that both the load bearing capacity and the diagonal

bracing of these walls by the means of the plaster surfaces (from 3 cm) is sufficient

to build all types of single family houses. And the tests were not made with posts in

the cross section dimensions of 4 x 1 8 cm but in the cross-section dimensions of 1 ”

(2,5 x 1 4 cm).

In order to be on safe side (in the case of timber construction, we always have

something oversized, and this is also a positive fact), we still recommend 4 x 1 8 cm

posts for load-bearing walls and one-sided diagonal planking. If this is outside (on

the façade), we install the diagonal planks at a distance of 6 - 1 0 cm (because for

exterior side the wood is not diffusively open enough (μ value over 20)) and fill the

gaps with a mixture of plaster and straw (as clay is hygroscopic, it draws moisture

from the dew point area and keeps our straw bales dry. If a wooden façade is

preferred, we plaster the outside with a diffusion-open 1 6 mm DWD plate (μ value

approx. 8, similar to lime plaster), then a ventilation layer (min. 5 cm) and then the

cladding. For many reasons (building physics, sustainability, residential health,

smart design for straw bale walls, self-construction suitability, resource

consumption), this externally diagonal braced CUT construction is the best

construction for straw ball walls in 1 to 2-storey residential buildings.

21


TIPS S2 – ORGANICUT

U2

004

CUT-Technique organic:

OrganiCut

Directly on both sides or on one side plastered straw bale walls can also be

produced in CUT technology as vault, semicircular (dome), chain line - thus in any

organic (curved) form. In this case, simply curved sections (for load-bearing walls,

for example, offcuts from 4 cm three-layer panels, for non-load-bearing walls

planks/posts from 24 mm cross-laminated-wood boards) are used as the posts.

Depending on the radius of curvature, the straw bales must be angled (with an

electric hand saw) or the wedge-shaped gaps must be filled (stuffed) with straw.

Such curved walls or organic buildings can be covered with a separate roof (on

external/internal construction posts), built as a vault in the attic space under an

existing roof or covered directly with a flexible (ventilated) roof membrane (EPDM

foil and green roof, flexible photovoltaic cells on EPDM shingles; see FabHouse

Barcelona), wooden shingles or sheet metal and thus made rain-proof. What has

previously been possible only in the concrete spraying method on metal rebars

(Flying Concrete) can be produced with this technique organically and with natural

building materials.

22

U2 – INFILL AND PREFABRICATION SESSION S2 – INFO 2

Hybrid Constructions – GREB

U2

25


SESSION PLAN S3

U2

Session Plan U2-S3: Infill Constructions

Objectives:

Trainees ...

know the infill construction techniques.


know the advantages and disadvantages of this solution.

can organize building sites during the infill process (i.e.: take


strawstacks fire protected, remove loose straw after work,… ).



know the details (window, roof junction,... ) for infill construction

techniques.

Methods:

Lecture / talk

Explanation

Practice

Trainer:

Place:

Workshop

Duration:

Min 1 day (7 hours)

Equipment:

Wood

Screws

Straw bales

Tools

Reed stucco

Theory

Different structural options of infill techniques and their

characteristics and bale requirements

Fixing bales with different techniques


Advantages and disadvantages of infill construction techniques

Details of connections: foundation, corners, windows, doors, roof ...



Documents:

Trainer sheet:

T1

Info sheet:

I1 Infill construction

techniques

Practice

Task:

Working groups

Preparing simple wooden frames and structures







Organization:




27


Infill (Post & Beam) Constructions

U2

28


Infill (Post & Beam) Constructions

U2

29


TIPS S3 – INFILL

U2

005

The Length of the Straw Bale

defines the Distance of the Posts

Usually, we design wooden post constructions (especially hybrid constructions like

CUT walls) where it is possible according to the length of the bales and not vice

versa. This does not mean that windows and doors are not planned where they

guarantee the best view or the shortest path. But where a wall has no openings, we

can measure the distances of the posts according to the longest bales. This ensures

that the straw bales (still bound with strings) will fit completely between the posts

and only the spaces/gaps between too short bales and the construction have to be

filled with additional flakes. By filling additional layers, we can also compress badly

pressed bales (below 90 kg / m3), which is particularly useful when the bales are

directly plastered.

30


TIPS S3 – INFILL

U2

006

Straw Bale Infill:

Vertical or horizontal?

Whether the bales are infilled horizontally in the wall (about 80-90 cm post spacing)

or vertically (47-50 cm post spacing), doesn’t matter much for the total insulation

value (including construction). The 36 cm balesd have the same direction in both

mounting positions. The wood consumption is larger (and thus cold bridges: wood

insulates less than half as well as straw) and often it is structurally not necessary.

The 47 or 50 cm is a fixed size (defined by the bale channel) and you don’t have to

fill up too short bales with flakes. However, you are more flexible with horizontal

bales on edge (all cavities of 1 0 to 1 00 cm post spacing can be filled with one or

several flakes or one whole bale + one or more flakes). This means that we do not

interfere with the architecture of a building. I personally regard grid dimensions of

rigid 80 cm only useful for prefabricated modules (see page 1 88).

31


TIPS S3 – INFILL

U2

007

Diagonal Bracing:

Withstand the Wind Forces

Timber constructions must be designed for vertical load transfer (timber

dimensions, prevention of the so-called buckling). Here the loads of the building but

also snow are taken by vertical posts and beams, avoiding any deflections

(buckling). But building / load-bearing construction must also be stiffened against

horizontal wind loads (shear forces). Diagonal reinforcement (bracing) can be

achieved through 3 cm plasters on both sides (sandwich-effect), as in the case of

load-bearing straw bale construction (proved by tests), but also by boards (from 1 6

mm OSB tongue & groove on the inside, 1 6 mm diffusion open DWD or Agepan

tongue & groove on the outside). Other methods to withstand horizontal loads are

diagonal bracing with 1 ” (2,5 cm) raw sawn planks, usually mounted at an angle of

45 ° or an inner box out of 1 0 cm thick KLH panels - glued cross-laminated wood (see

S-House Böheimkirchen, AT). Or in case of traditional buildings e.g. diagonal beams

to stabilize the connection of a post and beam (known from Fachwerk-

Constructions), but also existing concrete or brick walls, which are the insulated on

the outside (Wrapping).

32


TIPS S3 – INFILL

U2

008

Planking or Direct Plaster:

Requirements to a Structural Wall

Whether the bales on both sides or on one side are directly plastered or additionally

diagonally braced, depends less on the required fire protection (this can be adjusted

with the plaster thickness from 3 cm from F30 to F 1 20; compare FASBA tests for fire

protection, DE). It’s more depending on wind forces or the need for installation areas

(electrics, water, sewage, ventilation) and the montage of e.g. kitchen shelfs. While

direct plastered walls are common and thoroughly tested in (load-bearing) straw

bale walls for one-to-three-storey buildings without additional diagonal bracing, the

wind forces can hit facades so severly that even conventional planking is not

enough. So it depends on the architect or structural engineer, where he plans and

places the bracing in the construction of the building: in the plastered or planked

straw bale walls, by using interior walls for structural bracing (diagonally braced

post & beam, KLH, brick, concrete) or - completely separated from the outer walls -

braced structures usually made out of concrete (Plattenbau). In any case, carpenters

naturally tend to prefer diagonal bracing from wood, masonry/brick/concrete

builders rather from concrete or bricks and plasterers usually are not asked.

33


TIPS S3 – INFILL

U2

009

Plasters as diagonal bracing Layers

(Sandwich-Walls)

Nevertheless, it is worthwhile to include the plaster at least in the calculation of the

wind reinforcement, particularly in view of the social housing construction and its

demanded production prices. No one will be surprised that both sides planked (loadbearing)

straw bale walls cost twice or three times as much as directly plastered

walls. Even if the entire walls of a building (without windows) are only between 1 8%

(single-family house) and 1 0% (multi-family house) of the costs of a house, no one

will ever be able to build a sustainable and ecological residential building according

to the prices of Social housing without keeping all the costs as low as possible. Then

we leave the field to the (chemical) industry and its lobbyists.

34


TIPS S3 – INFILL

U2

010

Wood Dimensions: Double Posts in

the width of the Bales

When selecting the statically suitable wood dimension, it is important to consider

constructively 4 factors: the deflection (which we want to avoid), the diagonal

bracing (against horizontal wind forces), the transverse wood pressing (how far a

vertical wooden post is pressed into a horizontal wooden base plate) and finally the

size of the surface for the assembly of eg bracing boards or diagonal planking.

In straw bale construction we usually use post dimensions of 6 x 36 cm (or two

straw-insulated double posts 1 4 x 5-6 cm) for 1 -2 storey-houses. The narrow side (5-6

cm) of the posts offers enough space (as a rule of thumb: we need 2 cm next to a

nail/bracket/screw) to fix a reinforcing board or diagonal planking on it. Even if only

one post (usually the inner post of the wall) bears the horizontal loads, the second

post offers a possibility to mount all kinds of panels (OSB/DWD-boards, sound

insulation, installation areas). Care must be taken in the condensation (dewpoint)

area on the outside, to ensure that there is no air gap between the outer panel and

the straw, which could lead to convection and thus to condensation.

.

35


TIPS S3 – INFILL

U2

011

Wood Dimensions:

Buckling & Compression

The deflection (buckling) is thus prevented on the one hand by the timber

dimensions on the other hand by screwing / nailing of the planks and boards. Good

to know that wood cannot be compressed (significantly) in the length direction. For

the cross-wood pressing, 4 x 1 4 or 6 x 1 4 or 6 x 36 cm posts also offer sufficient

support surfaces, so it would not be pushed into the base plate (to cause any cracks

in the plaster through settling). And regarding the diagonal bracing wooden boards

(1 6 mm OSB tongue & groove, 1 6 mm DWD or Agepan tongue & groove) or

diagonal bracing (25 mm planks) can be used instead of the earlier used (traditional)

corner timber bracings (which are situated in the insulation layer and thus create

thermal bridges and make the infill much harder). The building physics requirements

must also be met for the planking: outside diffusion open and windproof (in

combination with the plaster surface or taping the gaps), inside air-tight (plaster).

36


SESSION PLAN S4

U2

Session Plan U2-S4: Prefabrication and Modules

Objectives:

Trainees ...

know different prefabrication and modular building methods.


know the advantages and disadvantages of these solutions.

can organize building sites during infill process (i.e.: take responsibility

to leave the building site rain- and windproof, keep strawstacks

fire protected, remove loose straw after work,… ).



know the details (window, roof junction,... ) for prefabricated walls

and modules.

Methods:

Lecture/talk

Explanations

Practice

Trainer:

Place:

Workshop

Duration:

Min 1 day (7 hours)

Equipment:

Wood

Screws

Straw bales

Tools

Reed stucco

Theory

Different construction options for prefabrication and their characteristics

and bale requirements

Fixing bales with different techniques


Advantages and disadvantages of infill construction techniques

Details of connections: foundation, corners, windows, doors, roof...



Documents:

Trainer sheet:

T1

Info sheet:

I1 Prefab

Practice

Task

Working groups

Preparing wooden frames and structures







Organization:




38


Prefabrication and Modules

U2

ASBN, Kreativer Holzbau & Bauatelier Schmelz)

StrohTec + ASBN, Austria (1 999)

39


TIPS S4 – PREFAB

U2

01 2

Multistorey Residential Buildings:

Prefab-Modules

Straw bale walls in the multi-storey residential buildings have usually seperate loadbearing

structures (KLH boards [glued cross-laminated wood]), load-bearing brick

walls, concrete columns, concrete slabs as ceilings, (encapsuled) timber posts or

Fachwerk-constructions). In many cases, this load-bearing structures are already

braced against horizontal wind forces. Such timber constructions can be used similar

to the one to two-storey straw bale buildings. Moreover, hybrid designs such as the

CUT technology are a good choice. Also Wrapping (with an external thermal straw

bale insulation layer) of load-bearing and already diagonally braced KLH plate boxes

can also be easily combined with (non-loadbearing) hybrid constructions to support

and fix the insulation layer. In the case of increased fire protection requirements,

prefabricated modules - which are covered with fire-retardant DWD/Agepan panels -

can also be fixed to the supporting structure. A solution is provided by an Austrian

innovation (system / house / construction), which has been developed in cooperation

with the ASBN: 40 cm flakes of so-called (Krone) multibales are filled between Steico

posts 36 x 4.5 cm in the grid of 80 cm and outside 1 6 mm DWD, inside 1 6 mm OSB.

40


TIPS S4 – PREFAB

U2

01 3

Prefab-Moduls with

Bale Layers (Flakes) by Multibaler

Multibaler big bales have a cross-section of 75 x 1 25 cm and are tied up to 9times to

provide thicknesses from 30 to 40 cm (or more). 2 such layers, filled into a module,

incl. 4 cm base and top plate (Steico plywood) provide the dimension of 80 x 255 cm

with individually adjustable insulation thickness (suitable for passive houses). The

modules can be connected to each other with a flying feather (tongue) made of 4 cm

softfiber boards such as tongue and groove elements. Since the insulation value of

straw bales is the highest in the direction of the bale canal (through the flakes), the

Austrian multibales are offered as certified construction bales (approved building

material) and the filling of 2 layers between the plates (from the top with a funnel)

goes quickly and easily. Similar prefab modules are also used for the highest 7-

storey straw ball house in St. Die des Vosges. As suspended modules in front of the

load-bearing KLH construction.

41


SESSION PLAN S8

U2

Session Plan U2-S8: Timber Construction

Objectives:

Trainees ...

have the ability to crosscut and connect wooden posts and beams.

can fix a baseplate to the foundation, install a windowframe, make

a corner and a ringbeam (for roof or intermediate ceiling).

can make a production planning and production drawing of a wall

with windows and doors.

can make a production drawing of ceiling joists.

can calculate the amount of materials needed for a timberconstruction

(bill of quantities).

know the details of a wall (connections foundation-wall, wallwindow/door,

wall-ceiling, wall-corner-wall, wall-roof).

Methods:

Lecture/talk

Explanation

Trainer:

Place:

Classroom and construction

site

Duration:

4 hours

Equipment:

Pen and paper

Beamer

Construction wood

Structural boards

Machines to cut wood

Tools to nail and screw

Theory

Structural engineering (loads/bracing)

Wood construction and wood connections

Production-planning and -drawing

Calculation (bill of quantities)

Details

Calculate the building costs (material, labour, etc.)

Documents:

Trainer sheet

T1

Info sheet

I1 Timber Construction

Text sheet

X1

Powerpoint:

Ppt1 :

Practice

Organization:

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.

42


Timber (Post & Beam) Construction

U2

43

44


SESSION PLAN S9

U2

Session Plan U2-S9: Regulations and Organization of Building Sites

Objectives:

Trainees ...

know national or regional regulations relevant for straw bale

constructions.

know how to organize their straw bale work on a building site.

know specific problems of straw bale building site organization.

can organize building sites during infill process ( i.e.: take


strawstacks fire protected, remove loose straw after work,… ).

Methods:

Presentation

Talk

Trainer:

Place:

Classroom

Duration:

Min. 2 hours

Equipment:

Projector

Pen and paper

Theory

Building law or regulations for straw bale building

Organization of a building site (materials, tools, machines, waste,

access,… )

Security measures (how to behave in case of accidents,… )

Specific problems and risks of straw bale building site

organization

Storage and protection of straw on the building site

Documents:

Info sheets:

X1 Regulations

X2 Building site

Task

Short visit of a building site

Practice

Organization:

Looking for an appropiate building site in the surroundings

45

46


SESSION PLAN S7

U2

Session Plan U2-S7: Straw Bale Infill and Stuffing

Objectives:

Trainees ...

know about the infill process, right density (compression) and

how to avoid gaps.

know various methods to compress the bale in a construction.

know how to fix a bale in the construction.

know how to use the tools required for the infill process

(compression, cutting, infilling, stuffing).

know how to stuff/fill gaps with straw or complementary

insulation materials.

know how to prepare the substrates for plastering and cladding.

know how to coordinate the infill process with other craftsmen at

the building site.

Methods:

Workshop

Practice

Trainer:

Place:

Workshop

Duration:

Min 5 days

Equipment:

Straw bales

Stuffing tools

Cutting tools (Alligator)

Compression tools

Boards

Construction wood

Theory

Documents:

Trainer sheet:

T1

Practice

Infill, compress, fix,cut, shave,… straw bales and complementary

insulation materials in a sample wall

Make the wind and airtight connection to the straw bale wall

sample

Prepare the substrate for plasters and cladding

Operate a controlling of the realized work (gaps, density, stability

of bales, compression, surface)

Organization:

Prepare sample walls in different construction systems (hybrid, infill, prefab)

Organize materials and tools

47

STEP – Straw Bale Training for European Professionals

UNIT 2 – Infill & Vorfertigung/Prefab (201 7)

Editors/Tips: Herbert Gruber, Helmuth Santler (ASBN)

Coworking: BuildStrawPro-Team (Erasmus+ Project)

Design & Photos: Herbert Gruber (ASBN, StrohNatur),

Add. Photos: RFCP, provided by Architects & Companies

Illustrations/Icons: Alejandro Lopez, Michael Howlett

This Handbook bases on

the Handbook of the

Leonardo-Team STEP (201 5)

STEP U2 Handbook EN

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