ARGE – construction partnership in Germany: legal issues in cooperation of different engineering firms

Table of Contents

I DECLARATION IN LIEU OF OATH

II EXECUTIVE SUMMARY

IV LIST OF ABBREVIATIONS

V LIST OF FIGURES

1 INTRODUCTION

2 PROBLEM DEFINITION

3 CONTRACT RELATIONSHIPS IN CONSTRUCTION PROJECTS
3.1 Contract to produce a work and service contract
3.2 Architecture and Engineering relationships
3.3 Linkage to HOAI
3.4 General planner

4 PURPOSE AND TYPES OF ARGE BETWEEN ENGINEERING FIRMS
4.1 Purpose of ARGE
4.2 Types of ARGE

5 LEGAL FORMS OF ARGE
5.1 Basic legal form of ARGE: Partnership under Civil Law
5.2 Other legal forms
5.3 Differentiation from other coalitions

6 FOUNDATION OF ARGE FOR ENGINEERING FIRMS

7 INTERNAL RELATIONSHIP
7.1 Bodies and their tasks
7.2 Contributions and performance
7.3 Contravention
7.4 Internal Liability
7.5 Withdrawal or exclusion of an ARGE member
7.6 Performance bond

8 EXTERNAL RELATIONSHIP
8.1 External representation
8.2 Liability
8.3 Insurance for external relationships
8.4 Insolvency of ARGE

9 CLOSING AND DISORGANIZATION OF THE ARGE

10 PARTIAL INVALIDITY OF ARGE

11 TAX TREATMENT OF THE ARGE

12 CONCLUSION

13 BIBLIOGRAPHY
13.1 Literature
13.2 Other sources
13.2 Internet

14 LIST OF JURISDICTION

I Declaration in lieu of oath

I hereby declare that I produced the submitted paper with no assistance from any other party and without the use of any unauthorized aids and, in particular, that I have marked as quotations all passages, which are reproduced verbatim or nearby-verbatim from publications. Also, I declare that the submitted print version of this thesis is identical with its digital version. Further, I declare that this thesis has never been submitted before to any other examination board in either its present form or in any other similar version. I herewith disagree that this thesis may be published. I herewith consent that this thesis may be uploaded to the server of external contractors for the purpose of submitting it to the contractors' plagiarism detection systems. Uploading this thesis for the purpose of submitting it to plagiarism detection systems is not a form of publication.

Stuttgart, 09.02.2012

II Executive Summary

This Master Thesis investigates and evaluates the legal framework for engineering firms to step into an ARGE partnership with other planning offices. ARGE, in German construction industry an established form of partnership, becomes more and more important in acquiring and accomplishing construction projects. Principals are interested in placing orders to ARGE partnerships, so they force it in tender procedures.

Reasons therefore are that the ARGE underlies the regulations of the German Partnership under Civil Law. Consequently the ARGE partners are jointly and several liable for the contract to produce a work with the principal. Thus the principal reaches fundamental advantages: He reduces his risk concerning insolvency of an ARGE partner, he increases competition and he gets services from one hand.

Engineering firms, who want to participate in these projects, have to handle their capacities and risks. Engineering firms are not interested in participating in ARGE partnerships. There is no reason for voluntary sharing of liability. Engineering firms want to be responsible and liable only for services they accomplish. They do not want to share the responsibility and liability with other construction planners.

Therefore engineering firms are interested in an ARGE agreement which divides the responsibilities and liabilities considering the rendered services. In external relationship with the principal, ARGE partners could not change the jointly and several liability. Principals will not deal about limitation of ARGE partners' liability. However in internal arrangements could be defined other regulations.

The ARGE model contract for building contractors, published by German Construction Industry Federation, could be adapted partly to the interests of engineering firms. From Chamber of Architects Baden-Württemberg published model contract is more suitable, because of equal treatment in liability and payment.

Beside the contract with the principal is the partnership agreement equally important. The ARGE agreement has to define the purpose of the partnership, the bodies of the partnership with their responsibilities and the services the partners have to accomplish for the ARGE. Partners have to be careful concerning liability. Partners should ensure in internal relationship that they are only responsible for services they had accomplished.

It is advisable to define other regulations in the ARGE agreement than the terms in law. For example, partners should define a fulfilment obligation, due to claim for damages by the principal. In case of insolvency of one partner, the other partners have still to fulfil the contract with the principal. If there are services they cannot carry out by themselves, they have to integrate other partners.

Engineering firms have to weigh within the framework of their business risk, if they are interested in acquiring the contract under the precondition to participate in an ARGE partnership. Capacity utilization is just important as the choice of partner.

IV List of Abbreviations

illustration not visible in this excerpt

V List of Figures

Figure 1: Relationships in construction projects

Figure 2: Contractual relationship with ARGE

Figure 3: Horizontale ARGE

Figure 4: Structure of Dach-ARGE

Figure 5: Transfer from pre-contract to ARGE agreement

Figure 7: Bodies of ARGE

Figure 8: Example for insolvency of an ARGE partner

Figure 9: Performance bond relationship

Figure 10: Liability for construction project

Figure 11: Ways of contractual exit

1 Introduction

Partnerships between construction companies become more and more important in accomplishment of large construction projects. Companies, who want to participate in large projects, have to handle their capacities and risks. Principals have their own interests: they are interested in increasing the competition, they want services from one hand and they also want to reduce their risks.

Engineering firms are also affected. How can small and mid-sized engineering firms acquire and accomplish large construction projects? There are different forms of partnership to enhance the capabilities and to fulfil the competition requirements.

Facing the competition requirements, the construction branch in Germany has established the partnership form of ARGE¹. This partnership is a special construction cooperation in Germany. It is widely recognized in partnerships between contractors and is legally supported². The ARGE partnership form is also supported by a model contract published by German Construction Industry Federation. The Chamber of Architects in Baden - Württemberg have also drafted a model contract for architects.

However, competitive conditions often pose high hurdles in Germany. Tenderer have to show their capability by disclosure of references, number of employees, office equipment and especially in procedures for supply and services of freelancers (VOF), they have to verify the professional experience of their employees.

Additionally, there are tenders which expect the foundation of an ARGE for example for architecture and engineering services³.

Engineering firms are not interested in accepting liability for services they are not competent for. Considering the principal, there are different interests which have to be coupled.

In this thesis will be discussed and illustrated the legal relations and difficulties of ARGE partnerships between engineering firms. Reflection starts with contractual relationships in the construction industry and the linkage to the Fee Structure for Architects and Engineers (HOAI). After that there was an overview about the ARGE structure, continued with screening the formal start - up requirements.

The main part of the thesis is divided in internal and external relationship. Liability and responsibility are the main terms which would be investigated in relation to principal and ARGE partners. After showing up the restriction possibilities considering insolvency of an ARGE partner or non-performing partners, the thesis comes to the end with an overview about tax matters.

The thesis was accomplished by starting in desk research, continuing in literature research and verification in jurisdiction. To get a practical relevance there were accomplished interviews with a CEO of an engineering firm⁴ and an interview with a tax consultant⁵.

2 Problem Definition

Usually there are different persons involved in the construction of a building. There are the principal, who could be the building owner or investor, the architect, planners and building contractors. Architects and planners are assigned by the building owner to consult him and to consider building laws and technical regulations. Architects and planners act on behalf of the principal on the construction site. Based on this frame conditions, they are practically the contact persons for contractors and building authorities.

Planners are employed in engineering firms. In Germany there are more than 35.000⁶ engineering firms for building services. They are responsible for the different parts of the technical systems within the building. In general, the services are divided in mechanical engineering and electrical engineering. The majority of the companies only offer one of the before mentioned services.

Many builders expect to have one contractor for consulting and planning the building services. Therefore many companies organized themselves by commissioning or subcontracting the missing half. However, subcontracting can also be problematic. First of all, subcontracts are independent of the main contract. The principal has no contractual access to the subcontractor. One example from market is a constellation which is common and wide spread: an engineering office for HVAC - Systems has none specialist for electrical systems, in consequence they have to engage an engineering firm for the electrical engineering. Nevertheless there may come up difficulties in the construction phase. For example the contractor for the electrical system may deliver and install the wrong devices. Because of bad construction site management the subcontracted engineering firm for electrical systems is involved. Due to the main contract between building owner and engineering firm for HVAC - systems they are also involved.

Additionally there could arise some more problems at the end of the project. The acceptance and handover of the building is difficult in two ways, on the one hand due to the handover from the subcontractor to the main contractor and on the other hand due to the handover from the main contractor to the building owner. It could be that the subcontractor has finished his work earlier than the main contractor and wants to accomplish the acceptance in order to issue his final invoice.

Another problem could come up when the builder runs into financial difficulties and is not able to bring up the project costs, which leads to insecurities with regards to the overall project funding. In this case the subcontractor could only deal with his contracting entity. These described problems are not minor losses. 0n the construction site all parts of constructing a building are closely linked to each other. That means that the end date for the hand over to the builder could be delayed and cause significantly higher costs. At this point, mistakes become very expensive. And due to the contractual constellation - the engineering firm for HVAC - Systems is also involved.

A possible solution for remediation could be an ARGE. In Germany ARGE is known as a partnership between contractors for large construction projects which cannot be accomplished solely by one contractor. 0rganizing engineering firms in ARGE cooperation like contractors do could be a better instrument in working relationship for construction projects. The partners of the ARGE would then have a direct contract with the building owner.

Nevertheless an ARGE contract also incorporates risks and difficulties. There are internal and external regulations which to be taken into consideration. For example there could come up problems with external authorization, internal and external rights and obligations of the ARGE partners. But also more difficult problems like the situation when one partner of the ARGE could not fulfill his contract by less service provision. Another question is: How to cope with the insolvency of one ARGE partner?

The main problem for engineering firms in ARGE partnerships is that they are jointly and severally liable with other partners. Engineering firms want to handle or limit their share in liability⁷.

Literature is more focused on ARGE for contractors. Special literature for ARGE of engineering firms is not available. The regulations must be adapted to engineering firms, but not all subjects can be transferred. Engineering firms underlie different laws and regulations than contractors⁸.

3 Contract relationships in construction projects

3.1 Contract to produce a work and service contract

Architecture and engineering contracts are not specifically regulated In German Civil Code⁹. The German Civil Code regulates two relevant types of contracts: the contract to produce a work¹⁰ and the service contract. Construction, planning and consulting contracts, can be adapted to these in BGB legal regulated contract forms. The coherency to the German Civil Code is necessary to have a legal basis.

The service contract is defined in section 611 et seq. of BGB and the contract to produce a work is defined in section 631 et seq. of BGB¹¹. The two types differ fundamentally from each other, so it is very important to choose the correct type of contract.

Contract to produce a work leads engineering firms to a success-oriented, strict liability to develop a property free of defects¹². In contrast to contract for services the warranty period for buildings is five years¹³. Contract to produce a work has a wide range of applications in construction. All kinds of contractual cooperation are involved, also technical systems which are integrated in the building according to sections 93 and 94 of BGB¹⁴.

Construction is a development and realisation process, which the engineer has to accompany with planning and site management. So the work he has to produce develops during the construction realisation. So there are also elements of service contracts. But in German law they were consistently treated like contracts to produce a work¹⁵.

A contract for services does not contain any liability for success and does not include the claim for supplementary performance¹⁶. Example for service contract is the treatment contract with the doctor. The doctor does not promise the healing, he does promise the proper treatment. Considering the construction branch, service contracts, have no obligations to carry out an acceptance. So the builder has no possibility to find out if the work was completed according to the specifications and rules¹⁷.

An engineering firm owes not the construction of a building as a physical object. The engineering firm is obligated for a faultless planning and if appropriate the construction supervision according to the rules¹⁸.

As described, architects and engineers contracts are not defined as independently contract in German Civil Code. In prevailing case law engineers contract have to be assigned as contract to produce a work¹⁹. Objective of the contracts is the building of a structure.

3.2 Architecture and Engineering relationships

There are different contractual opportunities available to link the partners of a construction project. The builder could bind each partner with separate contracts. He could also only engage a general planner which offers all necessary planning services. In the most cases are many companies and people are involved in the construction of a building. For example the principal or client can be the owner who will use the building or an investor who wants to lease or sell the building. The principal will usually always try to get the best quality coupled with the minimum price. So there are many options to order a building in Germany. In this thesis is the focus on realizing a building by involvement of architects and planners, who are responsible for planning and supervising.

In Figure 1 is shown a general example for contractual relationships in construction.

illustration not visible in this excerpt

Figure 1: Relationships in construction projects²⁰

The principal has direct contracts with all partners which are involved in accomplishing the building project. The planners and architects are not only responsible for planning and supervising their trades, they also have the obligation of coordinating with each other. Technical contractors also have the obligation for coordination with each other and with the building contractor. In general the planners and architects have to work together with the executing company on behalf of the principal. Furthermore the architect is responsible to reach the building license for the construction project.

In this model has the principal contractual relationship with each of the construction partners. To simplify the project management on his side and to handle responsibilities and liabilities for accomplishing services, the principal is interested in bundling services. So he could bundle packages which fit to each other, like the building services, or for example the whole planning procedure.

Planners could join together for one construction project in terms of an ARGE. In Figure 2 is shown a possible contractual constellation with participation of an ARGE for building services.

illustration not visible in this excerpt

Figure 2: Contractual relationship with ARGE²¹

In this case the engineering firms for planning building services are centralized in the ARGE. The builder has only one contract for engineering the building services. As described, the contract form between the builder or investor and the ARGE for engineering is defined in the German Civil Code as contract to produce a work. This contract form is the most used contract form for construction projects.

Payment to each partner is regulated in the several contracts. References for payments to architecture and engineering firms are regulated in the HOAI.

3.3 Linkage to HOAI

The HOAI is a Fee Structure for Architects and Engineers, which allows calculating the remuneration based on the cost calculation of each trade. So the objective of the HOAI is to provide a calculation method to assist parties without fee agreement. Furthermore the prescribed calculating method is an instrument, to proof the remuneration agreement. It can be verified if the fixed fee is within the maximum and minimum rate.²²

The HOAI couples the ordered service to the scope of work. Scope of work is defined in the HOAI²³, where does not contain any information standardised by law on the content or scope of an engineer's contract²⁴. In legal practice engineering services are assigned to contracts to produce a work²⁵.

The HOAI is divided in services. Services which will be aligned have to be defined in the contract to produce a work between the engineering firm and the principal²⁶. The BGH has confirmed, that it is allowed to define services by reference to HOAI²⁷.

If the contract to produce a work contains only several parts from the HOAI, for example the service phase 8 - construction supervising, than the contract is also defined as contract to produce a work²⁸. According to the conviction of BGH²⁹ the scope of works, which are defined in the HOAI, could serve as a basis in the contract. Restriction is that the scope of work has to be mentioned in the contract.

Section 7 of the HOAI does not affect employment relationships. So Engineers and Architects, who have an employment contract with their employers or instruction dependent freelancers, have not the HOAI as their legal basis³⁰. In this case the HOAI can only be utilized as basis for interpretation.

HOAI payment agreements are often used for determination of shareholding in the ARGE. So in ARGE agreements, there can be a reference to the contract to produce a work. In this contract with the principal is defined the payment to the ARGE. Also could be linked the ownership-share ratio of the ARGE to the contract for work and services.

Partners of ARGE have to be ensuring to separate their services strictly horizontal. In this case the HOAI could be involved in the ARGE agreement. Payment could be coupled to the accomplishment of services.

3.4 General planner

As described before, many engineering firms and architects assign subcontracts with other firms in order to offer the entire planning service. This instrument, to meet the builder's needs, to reach all services from one hand, is called general planner³¹. However there are many difficulties which are coupled with subcontracts. For example the builder has no direct contractual relationship with subcontracted companies³².

According to the phases of the HOAI, the general planning contract could obtain different performances. For example can be instructed the object planning and the outside facilities. The same applies to the structure planning and sound insulation verification.

With subcontracts engages the general planner the appropriate consultants and engineering firms. The engineering firms have only contractual relationship with the general planner. The risks are apparent: the general planner has far reaching liability risks. He is liable for faulty planning of his subcontractors.

If subcontractors have not sufficient liability insurance, the general planner has no chances of success with a claim for compensation. The general planner has to close a liability insurance contract which covers the risks with subcontractors. A usual architect cannot act as a general planner, his liability insurance covers him not against losses which occur through subcontractors³³.

Also a disadvantage is to sign up a contract which contains minimum rates of HOAI fee structure. The general planner has to invoice individual subcontracts. According to HOAI, the single contracts fees are higher than the remuneration for the overall contract³⁴.

Reason therefore is that the HOAI is digressive - single contracts in the sum are higher than the overall contract. One more disadvantage is the risk for the general planner that he has to pay his subcontractors although he was not paid by the client. Risks can be reduced by terms in subcontractor contracts³⁵.

For engineering firms, is the preferred contractual position, the position of the subcontracted company³⁶. As subcontractor, the engineering firm has a clearly defined scope of services to accomplish. Liability is delimited just the same. On the other side, for general planners is the ARGE useful. They are used to be liable for all services. In an ARGE partnership they could share the liability.

4 Purpose and types of ARGE between engineering firms

4.1 Purpose ofARGE

In building practice many contractors need partners in accomplishing construction projects. Partnership is not only necessary because of the size of the construction site. There are also technical, economic and organisational reasons.

First of all capacity or manpower is a reason to set up a partnership. Coupled with this reason is the time pressure of investors, who want to accomplish projects in shorter construction time. Specialized sole proprietorships have also reason to form partnerships. They need partners to offer entire services. Sole proprietorships and small companies have to face difficulties in entering the bidding process for large construction projects. They need partners to show that they are inclined to accomplish successful the contract to produce a work³⁷. Companies have to be aware of their solvency and flexibility according to their business activities³⁸. Size of contract should not commit the whole company and should not exceed companies' capacity.

According to section 6 of German Contract Construction Procedures (VOB) part A, bidding consortiums are equal to all other bidders. In this context ARGE partnerships are supported, due to partnership of mid-sized companies the competition will be higher³⁹. Certainly must be mentioned, that VOB part B cannot be agreed in engineering contracts⁴⁰. So the VOB as German Construction Contract Procedures have no influence in engineering contracts.

On the one hand an ARGE partnership increases the solvency and capacity of the partners; on the other hand the economic risk will be shouldered by partners⁴¹. As described in the previous chapter, ARGE is a useful partnership for general planners. General planners are responsible for the entire services. With the ARGE the partners have also to shoulder the liability.

Additional reasons for engineering companies are pre-financing and liability. Usually they are required to finish a phase according to HOAI before they get a payment.

There are also advantages for the principal. One important advantage for the builder or investor is the reduction of risk. If one member of the ARGE could not fulfil his part or becomes insolvent, the other members have to fill out the space and are still in duty to complete the project work⁴². From the principals point of view, the ARGE simplifies administrative and coordination expenses.

4.2 Types of ARGE

There are mainly two types of ARGE: the horizontal ARGE and the vertical ARGE. The horizontal ARGE is the widely recognized form of ARGE. The partners provide services to accomplish the project. The partners could have different focusses on performance. In picture 3 is shown the constellation of horizontal ARGE.

illustration not visible in this excerpt

Figure 3: Horizontale ARGE⁴³

In this example the ARGE consists of three partners. For example company A could be the engineering firm for planning the electrical systems, company B could be the engineering firm for HVAC - Systems, and company C could be the planner for the sprinkler system.

The builder has a contract with the ARGE which was founded by three companies. The three partners have to provide, manpower, machines, etc. All members are jointly responsible for accomplishing the project. The contractual relationship within the ARGE is not important for the principal; he gets all services from one hand.

In the ARGE agreement has to be defined which kind of capacities, contributions and performances the partners have to bring into the ARGE. In this case, the capacities will be technical and specialised knowledge, manpower and deposit to start working the ARGE.

The other type of ARGE or a variation of ARGE⁴⁴ is the so called Dach-ARGE or vertical ARGE. In external relationship there is no differentiation between horizontal and Dach-ARGE. Internal arrangements specify that that the services of the Dach­ARGE have to be divided into smaller packages. This smaller package will be subcontracted from the Dach-ARGE to each of the partners as subcontractor. All construction services will be accomplished by subcontracting the Dach-ARGE members. The Dach-ARGE does not accomplish direct services, but one possible task could be the responsibility for coordination.

Thus in internal relationship the partners are not liable for the complete service which the Dach-ARGE has to deliver, they are only responsible and liable for the subcontracted part⁴⁵. So this type of Dach-ARGE supports only the exactly separation of the performance. Claims for defects could be addressed to the affected partner easier. This type will be founded when different partners yield different services⁴⁶, and when the services could be precisely differentiated. The structure of Dach-ARGE is shown in picture 4.

illustration not visible in this excerpt

Figure 4: Structure of Dach-ARGE⁴⁷

In Dach-ARGE, partners have a dual role. On one hand they are subcontractor of the Dach-ARGE with all his duties and obligations, and on the other hand they are shareholder of the ARGE⁴⁸. Due to his position as shareholder, the partner has to fulfil his duty of allegiance towards the other partners⁴⁹. This duty goes beyond the common subcontract. Nevertheless each partner is full liable for the hole Dach-ARGE. So the liability in relation to the principal is the same as in an ordinary ARGE⁵⁰.

Disadvantage is still, that in case of insolvency of one partner, the other partners have to fulfil the contract with the principal - independent from the type of ARGE. The type of Dach-ARGE is useful to separate the service according to the partners. However the services from engineering firms could be clearly differentiated according to HOAI.

However there is coupled a higher administrative effort for the Dach-ARGE, because of separate subcontracts which have to be signed and recognized. Each partner will have two contracts: The contract with the principal, which is the same for all partners, and the individual contract with the Dach-ARGE. Contracts have to be congruent otherwise there result gaps in services, which could lead the Dach-ARGE in difficulties.

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¹ ARGE - in literature ARGE is defined contradictory. For example, on the website of Hochtief the term of "ARGE - Arbeitsgemeinschaft" is defined as consortium (http://www.hochtief.com/hochtief_en/117.jhtml, date 29.01.2012) In the model contract for ARGE -agreement of Hauptverband der Deutschen Bauindustrie e.V. ARGE is translated as „Joint Venture". In German the term "ARGE - Arbeitsgemeinschaft" is used as one time cooperation for one project. To prevent confusion the term "ARGE" is not translated and used in German language as fixed term.

² Heiermann, W. et al. (2008), page 155.

³ http://ted.europa.eu/udl?uri=TED:N0TICE:42398-2012:TEXT:DE:HTML&src=0, date: 08.02.2012.

⁴ Müller & Bleher Filderstadt GmbH & Co. KG.

⁵ Ellinger & Rückle Steuerberatungsgesellschaft Partnerschaft.

⁶ Federal Statistical Office Germany (2011), page 15.

⁷ Müller, M. (2012), Interview.

⁸ Krause-Allenstein, F. (2007), page 618.

⁹ Wirth, A. et al. (2004), page 47.

¹⁰ The German legal term „Werkvertrag" is translated in a variety of ways. For example in the Langenscheidt Routledge Technical Dictionary (3rd edition, 2007) is the legal term translated as „service contract" or „works contract". In Fidic - An Analysis of International Construction Contracts, the legal term is translated as „Contract for works". In this Thesis is used the legal term of „Contract to produce a work" inspired by the official translation of the German Civil Code.

¹¹ Mütze, M. et al. (2007), page 129.

¹² OLG Frankfurt (1981): Judgement from 27.05.1981 - 17 U 82/80, in BauR 1983, 156.

¹³ BGB (2009), section 634.

¹⁴ BGH (1997): Judgement from 15.05.1997 - VII ZR 287 /95, in BauR 1997, 1018.

¹⁵ Häußermann, D. et al (2008), page 27.

¹⁶ URL: http://www.brennecke-partner.de/48530/Der-Architekten--und-Ingenieurvertrag-als- Werkvertrag, date: 20.11.2011.

¹⁷ Wirth, A. et al. (2004), page 47.

¹⁸ Häußermann, D. et al (2008), page 27.

¹⁹ Simmendinger, H. (2009), page 1.

²⁰ According to: Häußermann, D. et al. (2008), page 14.

²¹ According to: Häußermann, D. et al. (2008), page 14.

²² Locher, H. et al. (2010), page 407.

²³ Häußermann, D. et al. (2008), page 35.

²⁴ Mütze, M. et al. (2007), page 127.

²⁵ Locher, H. et al. (2010), page 407.

²⁶ Häußermann, D. et al. (2008), page 35.

²⁷ http://www.baunetz.de/recht/BGH_bestaetigt_Bezugnahme_auf_Leistungsbilder_oder_ Leistungsphasen_der_H0AI_fuehrt_zu_entsprechender_Leistungspflicht_44766.html, date: 27.01.2012.

²⁸ BGH (1974): Judgement from 07.03.1974 - VII ZR 217/72, in BGHZ 62, 204.

²⁹ BGH (2007): Judgement from 26.07.2007 - V II ZR 42 / 05, in BGHZ 173, 314.

³⁰ BGH (1999): Judgement from 12.07.1999 - II ZR 4/98, in BauR 1999, 1471.

³¹ Wirth, A. et al. (2004), page 37.

³² Gauch, P. (1982), page 155 .

³³ Wirth, A. et al. (2004), page 37.

³⁴ Wirth, A. et al. (2004), page 37.

³⁵ Ibid., page 37.

³⁶ Müller, M. (2012), Interview.

³⁷ Jagenburg, I.; Schröder, C. U. (2008), page 11.

³⁸ Bärwaldt, R. (2002), page 1101.

³⁹ Heiermann, W. et al. (2008), page 155.

⁴⁰ Wirth, A. et al. (2004), page 47.

⁴¹ Bärwaldt, R. (2002)., page 1101

⁴² Ibid., page 1102.

⁴³ According to Messerschmidt, B.; Thierau, T. (2007a), page 9.

⁴⁴ Palandt, O.; Sprau, Hartwig (2008), section 705 marginal no. 37.

⁴⁵ Messerschmidt B.; Thierau, T. (2007b), page 3.

⁴⁶ Karl, S. (2007), page 636.

⁴⁷ According to http://bwi-bau.de/fileadmin/daten/pdf/Argeformen.pdf., date 05.02.2012.

⁴⁸ Jagenburg, I.; Schröder, C. U. (2008), page 40.

⁴⁹ Ibid, page 40.

⁵⁰ Ibid., page 40.