Design Development Phase in Architecture: Purpose, Process and Impact

What is the design development phase in architecture?

The design development (also known as DD) phase is the second major phase in architectural workflows, serving as the critical bridge between conceptual design and construction-ready documentation.

The DD phase requires architects to make definitive decisions when it comes to structural systems, mechanical layouts, electrical systems, and material selections. It eliminates design ambiguity and establishes the precise scope that will guide construction teams in the future. A lack of proper design development leads to expensive changes during construction and results in failures of coordination between building systems.

What is the purpose of the design development phase?

Design development is the architectural phase where general concepts become specific solutions. During DD, designs become build-ready blueprints with the help of architects, who go over all major building systems and construction requirements.

DD has three primary purposes:

1. Eliminating design ambiguity, forcing architects to make specific decisions about materials, systems, and construction methods.
2. Coordinating all building disciplines in order to prevent conflicts and issues during construction.
3. Establishing construction feasibility, proving that the design can be created using the available materials and construction practices.

How DD fits into the phases of the design process

Design development holds a strategic position in the traditional five-phase architectural process established by the American Institute of Architects (AIA). The DD phase precedes the preparation of construction documents but follows schematic design approval.

The architectural process consists of five primary phases:

• Schematic design
• Design development
• Construction documents
• Bid or negotiation
• Construction administration

The table below is presented as a visual aid to gain a better understanding of the different phases of architectural design.

It should be noted that this interpretation does not include the ever-important pre-design phase, but the AIA itself recognizes its architectural process as a list of suggestions rather than mandatory options, and different companies may have their own interpretations, including six architectural design phases instead of five.

DD serves as a quality control checkpoint where architects verify the constructability of their schematic designs. This phase helps design teams test different technical solutions, explore alternative options in terms of materials, and optimize building performance before committing to final construction documentation.

This phase also marks the transition from design exploration to design execution. Schematic design actively encourages creative problem-solving and multiple design options, but design development requires definitive decisions and technical precision in its choices. This changes the entire mentality, affecting the way architects approach their work and interact with project consultants.

Why the design development phase is critical

Design development is essential because it helps prevent expensive construction changes while ensuring project success. It is the last opportunity for architects to make major design modifications without resulting in a massive impact on both budgets and project schedules.

The primary reasons for the importance of the DD phase are:

• Clarity of communication: the accuracy of DD drawings and specifications helps all stakeholders to understand exactly what is going to be built from this point onward.
• Quality assurance: the DD phase ensures that architectural vision is translated into detailed construction plans, validating compliance with building codes and performance standards.
• Cost control: specific materials, systems, and construction methods help enable accurate cost estimation, making it possible for contractors to produce reliable pricing.
• Legal protection: DD documentation establishes clear and straightforward design intent with a defined project scope before construction is initiated, creating important legal protection for potential disputes down the line.
• Risk mitigation: Design development is used to identify potential construction issues before they become significantly more expensive field issues, simplifying conflict resolution to a certain degree.

Key elements and components of design development

The design development phase consists of detailed drawings, technical specifications, material selections, and coordination documents that all contribute to the transformation of schematic designs into construction-ready sets of documentation. These elements are connected with each other, as well, establishing the precise scope and technical requirements for construction teams on-site.

Primary components of DD include:

• Architectural drawings with detailed layouts
• Engineering system drawings
• Coordination documents
• Material specifications

Each component serves a specific purpose in the overall goal of preparing the project for successful construction.

Types of design development documents

Design Development documents are separated into four main categories that collectively describe all aspects of the future building. They work together to create a comprehensive project overview, which, in turn, helps with cost estimation, permitting, and the preparation of construction documentation.

The four main types of document in DD include:

1. Architectural drawings – Building sections, detailed floor plans, and elevations with accurate dimensions, wall types, and material indications to specify architectural features or room layout.
2. Engineering drawings – Mechanical, structural, electrical, and plumbing systems with equipment locations, routing details, and system capacities with coordinated layouts.
3. Specification documents – Written descriptions of finishes, materials, and construction standards to establish quality requirements and performance criteria for all building components.
4. Coordination documents – Detail studies and composite drawings to help identify and resolve conflicts between architectural elements or building systems.

Role of the architect in the DD phase

The architect is the primary coordinator during design development, maintaining design intent and project vision while managing input from all design disciplines. This role needs a balance between creative objectives, client expectations, and technical requirements, making it a challenging position.

The key architectural responsibilities in the DD phase include leading design team meetings to coordinate all disciplines and making final decisions about materials or building systems. At this stage, the architect is also responsible for ensuring compliance with building codes/accessibility requirements, maintaining design quality, and resolving technical challenges. Client communications and approvals for significant design decisions should be managed by the architect, as well.

The architect’s job here is to act as an integrator whose responsibility is to ensure that all building systems can work together without issues. This position requires a high level of understanding when it comes to how structural decisions affect architectural spaces, how mechanical systems impact ceiling designs, and so on. It is up to the architect to resolve conflicts between different systems or elements while making sure that changes do not affect the original design concept and that all client expectations about cost/schedule are met.

Creating detailed drawings and specifications

Understanding DD drawings

DD drawings require significantly higher precision than schematic designs, with highly-accurate dimensions, detailed connections, and specific material indicators. These drawings need to provide enough information to perform accurate cost estimation while highlighting clear construction intent.

The development of drawings is a highly systematic process comprised of at least four major steps:

1. Starting with updated floor plans showing accurate room layouts and dimensions
2. Developing building sections that offer floor-to-floor heights and major architectural features
3. Creating exterior elevations with specific materials indicated
4. Preparing preliminary details for complex architectural elements

Developing DD specifications

Specifications are developed alongside the drawings, with architects being responsible for researching specific products, establishing performance standards, and writing clear requirements for installation. DD specifications focus on major building systems and materials, leaving detailed product selection for construction documentation (the next phase of architectural design).

Quality control procedures are needed to verify that drawings and specifications are properly coordinated and offer a sufficient level of detail for the following project phase. These procedures:

• Ensure that specifications match the indications on the drawings
• Confirm that mechanical and electrical systems fit into architectural spaces
• Verify that all spaces are properly defined 
• Check overall dimensional accuracy

Transitioning from schematic design to design development

The transition from schematic design to design development is a drastic shift in the architectural process, moving from conceptual design exploration to technical precision. Architects must make specific decisions about building systems, materials, and construction methods while preserving the pre-approved design concept.

A successful transition process includes not just the conversion of general design concepts into specific technical solutions but also coordination with engineering consultants to develop building systems and the establishment of a detailed project scope for accurate cost estimation and construction planning.

Key differences between schematic design and DD

Schematic design and design development serve distinct purposes in the architectural process, with each phase needing a specific range of skills, deliverables, and client interactions.

The biggest differences between the two phases are:

• Level of detail – schematic drawings show general room layouts and the basic form of the building, while DD drawings need to specify exact wall types, dimensions, and system locations.
• Decision-making approach – schematic design explores different options and alternatives, while DD requires definitive decisions about construction methods, materials, and systems.
• Technical coordination – schematic design focuses on architectural concepts with minimal engineering input, while DD needs to create extensive coordination routes between all building disciplines.
• Cost implications – schematic design provides rough cost estimates using square footage, while DD performs detailed costs analysis via specific systems and materials for calculations.
• Client approval process – schematic design seeks approval for the general direction of the design, while DD needs approval in terms of specific materials, finishes, and technical solutions.

The shift from exploration to execution changes the way architects approach their work, necessitating more technical knowledge and detailed coordination skills.

Maintaining design intent during the transition

Preserving the original design intent becomes difficult during the transition to DD, as technical requirements and budget constraints often force design modifications at different levels. Architects must balance creative vision with practical construction realities in order to succeed during this phase.

Noteworthy strategies for maintaining design intent include:

1. Finding creative technical solutions in support of the original concept
2. Prioritizing design elements based on their value to the project vision
3. Identifying core design concepts that must remain no matter what

Successful architects also try to develop their own alternative approaches to achieve the same design goals via different technical means.

Client communication becomes particularly important during this transition process, as architects need to describe exactly how certain technical decisions support or modify the original design vision. This includes the need to translate complex technical information into understandable terms, managing client expectations about costs and design changes.

Documentation of design intent ensures that technical decisions remain aligned with the pre-existing concept. This includes written design narratives, reference images, or precedent studies to remind the design team of the project’s core objectives during technical development.

Common challenges when moving to DD

The transition to design development creates a number of recurring challenges that have the power to derail projects if they are not managed properly. Knowing about these challenges beforehand can help architects with preparing effective strategies for the successful completion of DD.

Technical coordination issues

Technical coordination is the most common challenge in design development, since architects have to integrate multiple building systems while upholding design integrity. Structural engineering requirements can conflict with architectural spaces, mechanical systems may require more space than expected, and electrical needs may impact furniture layouts. These are just a few examples of issues that architects might encounter during the DD phase.

Budget constraints

Budget limitations are common for DD, as detailed cost estimates tend to reveal that the existing schematic design does not fit in the available budget. As such, it is up to architects to re-evaluate design decisions, explore alternative materials, or modify building systems while keeping essential design elements intact.

Client decision-making

Client-side decision-making commonly delays the progress of DD when clients do not approve specific materials, finishes, or technical solutions. It is up to architects to prepare clear presentations and other means of helping clients understand the implications of their decisions, aiming to maintain project momentum through the approval process.

Schedule pressure

Pressure to keep up with the schedule intensifies during design development, given that technical complexity can sometimes require more time than anticipated. Coordination meetings with consultants, design revisions based on technical discoveries, and client approval processes can assist in extending the DD timeline beyond original projections.

Deliverables and outputs of design development

The design development phase produces specific deliverables that serve as the foundation for the preparation of construction documents and accurate project cost estimation. These outputs are the culmination of technical coordination efforts, creating clear documentation of all design decisions made during the DD phase.

DD deliverables must contain sufficient detail to enable contractors to provide reliable pricing, establishing the precise scope for the preparation of construction documents in the process. The quality and completeness of the outputs has a direct influence on the success of subsequent project phases.

Standard DD phase deliverables

Every design development phase produces a standardized set of deliverables that collectively describe the complete design of the building. These deliverables follow industry conventions established by the American Institute of Architects and other professional organizations in the field.

Architectural deliverables are the core of DD documentation, including:

• Floor plans with wall types and room dimensions
• Building sections showing floor-to-floor heights and major architectural choices
• Exterior elevations with material indications
• Preliminary details for complex architectural elements

Exact room layouts, door and window locations, and architectural finishes are specified in this group of DD deliverables.

Engineering deliverables are produced in the form of coordinated drawings that are integrated with the architectural design, including:

• Structural drawings with foundation systems and framing layouts
• Mechanical drawings indicating ductwork routing and heating, ventilation, and air conditioning (HVAC) equipment
• Electrical drawings specifying the logic of power distribution and panel locations
• Plumbing drawings showcasing major piping routes and fixture locations

The specification sections describe the materials, finishes, and construction standards of major building systems. They establish quality standards and performance criteria that cannot be shown graphically. Common examples of DD specifications are structural systems, exterior envelope materials, interior finishes, special construction requirements, and mechanical or electrical engineering equipment.

Cost estimation support includes detailed quantity takeoffs, material specifications, and system descriptions: everything that helps contractors create accurate pricing estimates. DD deliverables must provide enough detail to support cost estimate efforts within acceptable accuracy ranges for project budgeting purposes.

Preparing construction documents

The DD deliverables are the foundation for the preparation of construction documentation, necessitating careful organization and quality control to ensure a smooth transition to the following project phase. The process combines technical coordination and documentation management.

The technical preparation of design development documents includes:

• Resolving all major issues of coordination between building systems
• Finalizing material selections and specifications
• Completing preliminary reviews of code compliance
• Establishing dimensional accuracy throughout all drawings

Quality control procedures are responsible for verifying that all deliverables are properly coordinated and contain sufficient detail for developing construction documents.

Documentation organization is another important element of this process, streamlining the preparation of construction documents and reducing the risk of errors or omissions. It often includes the creation of project databases, specification outlines, as well as the preparation of outline specifications and the establishment of consistent drawing standards.

The client approval process plays a part here, as well, ensuring that all DD deliverables receive proper authorization before the construction document phase begins, including formal presentation, the documentation of all approvals and decisions, and the establishment of a baseline project scope.

Quality control and review processes

Comprehensive quality control during the DD phase prevents errors from appearing in construction documents, ensuring that all deliverables meet the necessary professional standards. These review processes include both internal team coordination and external consultant verification.

• Internal review procedures include the verification of dimensional accuracy, the coordination of architectural design with structural or mechanical systems, and the verification of the fact that the document specifications match the indications on the drawings.
• External review processes include coordination with engineering consultants, reviews of cost estimates, client review sessions for necessary approvals, and more, offering an independent verification of design decisions while helping identify issues that may have been missed by internal reviews.

Documentation standards ensure that all DD deliverables offer clear communication to construction document teams, such as through established drawing conventions, accurate project databases, or clear transmittal documents.

Technology and collaboration in design development

Modern design development relies greatly on digital tools and collaborative workflows to manage the complex coordination required between architects, engineers, and consultants. The integration of technology has dramatically transformed the way design teams approach the coordination of DD, moving from traditional paper-based processes to real-time digital collaboration platforms.

The success of any DD phase depends on seamless coordination between disciplines simultaneously working on interconnected building systems. Effective collaboration prevents expensive coordination errors, ensuring that all team members remain aligned with project goals and technical requirements throughout the development process.

Digital tools for management of the DD phase

Digital tools have revolutionized design development coordination by enabling real-time collaboration and the automated detection of conflicts between different building systems. These technologies help get rid of many traditional coordination challenges while improving project efficiency and design quality.

Building information modeling (BIM) platforms serve as the foundation for modern DD coordination, making it possible for architects and engineers to work within shared digital models. Popular examples of BIM software include Autodesk Revit, Graphisoft ArchiCAD, Vectorworks, and Revizto. Each offers a specialized toolset for different aspects of building design and coordination.

Key digital tool categories include:

• Clash detection software identifies conflicts between different building systems automatically, generating prioritized resolution reports
• Cloud-based collaboration platforms enable real-time file sharing and version control across distributed design teams
• Project management tools coordinate review schedules, track the completion of deliverables, and manage approval workflows
• Visualization technologies help identify coordination issues using immersive design reviews (including both virtual reality and augmented reality tools)

To simplify the understanding of the nature of clash detection workflows, we have created a simple diagram that showcases major steps in this workflow that need to be mentioned:

Integration capabilities between different software platforms allow design teams to maintain coordinated workflows while working with specialized tools for different disciplines. This integration helps prevent information silos while ensuring that all team members are working with the most up-to-date information.

Coordinating with engineers and consultants

Successful coordination of DD requires clear communication protocols and structured workflows which define the roles, responsibilities, and decision-making processes of all project disciplines. Effective coordination helps prevent design conflicts while maintaining quality standards and project schedules.

Weekly coordination meetings create the primary forum for interdisciplinary collaboration, bringing together architectural, structural, mechanical, electrical, and specialty consultants to review progress and resolve emerging issues. Meeting agendas usually address dimensional conflicts, system routing issues, equipment space requirements, and concerns around material compatibility.

Phased approaches to coordination assist in managing complex DD projects by breaking coordination into manageable stages. Early coordination has a strong focus on major system layouts and space requirements, intermediate coordination addresses detailed routing and equipment placement, while final coordination resolves the conflicts remaining in the preparation of  construction documents.

Documentation requirements for DD coordination include meetings which record all decisions, as well as coordination drawings with resolved conflicts and approval records that confirm consultants’ agreement with the design solutions. This documentation offers important reference points for the preparation of construction documents and protects against future disputes when it comes to design intent.

How project complexity influences DD requirements

Project complexity has a direct impact on DD coordination requirements through a variety of factors, such as building type, regulatory requirements, and environmental conditions. Complex projects require more extensive coordination and specialized expertise from additional consultants and technical specialists.

Complexity indicators help design teams anticipate DD coordination challenges, allocating appropriate resources when necessary. Building height and structural requirements affect coordination between architectural and structural systems. The complexity of mechanical systems influences ceiling space requirements and architectural design decisions. Technology infrastructure needs have an impact on electrical system design, necessitating specialized IT coordination in some cases.

Factors of regulatory complexity include:

• Specialized building codes for healthcare, educational, and institutional projects
• Historic preservation requirements for projects involving existing buildings
• Environmental compliance for situations where specialized permits are required, along with environmental consultations

Geographic and environmental factors also influence DD coordination requirements. Seismic design requirements affect approaches to structural coordination, climate-specific systems require dedicated mechanical coordination, and the availability of local materials may require coordination with suppliers during the DD phase to ensure construction feasibility.

Common challenges and solutions in the DD phase

Design development has several predictable challenges which can derail project schedules, lead to exceeded budgets, and compromise design quality if not resolved properly. Knowing about these issues and how to resolve them assists architects greatly in navigating the DD phase while maintaining project momentum.

Managing client changes during DD

Client changes during design development are one of the most disruptive issues architects face, as modifications this late in the design process require extensive coordination and a lot of effort, substantially affecting both the project cost and its schedule. Effective change management is the best way to deal with this, necessitating clear communication protocols and structured decision-making processes.

Common client change scenarios include space programming modifications (which require updates to structural coordination), material upgrade requests (which affect multiple building systems), and aesthetic changes (which impact mechanical and electrical system layouts). Every change has a series of cascading impacts throughout the coordinated design, potentially causing many other changes to the design that have to be carefully managed.

Successful change management strategies include:

• Clear approval processes with formal procedures for documenting client decisions and obtaining written authorization for scope modifications
• Development of alternative solutions with the aim of achieving client objectives while minimizing disruptions to design systems that are already coordinated
• Impact assessment procedures to systematically evaluate how proposed changes will affect building systems, project costs, or construction schedules
• Cost transparency to provide details of all cost implications of proposed changes, including construction costs, design fees, and schedule impacts

Communication protocols are also important and should be mentioned separately, as they help prevent misunderstandings about the implications of changes by requiring architects to explain how modifications affect other building systems. Written change documentation is a clear record of all decisions and their associated costs, and it serves as a protective measure for both architects and clients in the event of disputes or other issues.

Resolving technical coordination issues

Technical coordination conflicts arise when building systems compete for the same space or when design decisions create incompatible requirements for disciplines. These conflicts need to be resolved in a systematic manner in order to maintain design integrity and prevent problems in construction.

Typical coordination conflicts include:

• Structural beam depths that conflict with mechanical ductwork routing
• Electrical panel locations that interfere with architectural features
• Plumbing fixture requirements that are not aligned with structural grid systems

Proper resolution requires collaborative problem-solving between all affected disciplines.

Effective resolution strategies begin with the early identification of conflicts through regular coordination reviews and clash detection software. Prioritization systems help design teams focus on the most critical conflicts first, while the development of alternative solutions helps ensure that resolutions don’t create new issues with other building systems.

Collaborative resolution processes include facilitated coordination meetings where all affected disciplines participate in the development of solutions, technical workshops to explore alternative approaches, and design charrettes that formulate creative solutions to complex coordination challenges. Decision-making protocols establish clear authority structures for resolving conflicts when disciplines disagree about optimal resolution methods.

Documentation requirements for the resolution of coordination issues include:

• Notes on the development of solutions
• Approval documentation to confirm that all disciplines agree with proposed solutions
• Records of the identification of conflicts

This documentation acts as important reference material for the preparation of construction documents and future project phases.

Timeline and budget considerations

Scheduling challenges in the DD phase tend to arise from underestimating the time required for the technical coordination and client approval processes. The development of realistic timelines must include awareness of both the administrative requirements of client decision-making and the technical complexity of coordination work.

Budget pressure scenarios are common when detailed DD cost estimates reveal that schematic design concepts exceed the limits of the available project funds. Effective budget management is the solution here, necessitating proactive cost monitoring and the development of alternative solutions to maintain design quality while also meeting financial limitations.

Schedule management strategies include:

• Building coordination time into project schedules
• Establishment of clear milestone deadlines for client decisions
• Development of contingency plans to address unexpected technical challenges

Buffer time is a useful concept here. It entails reserving additional time frames beforehand to accommodate for the iterative nature of DD coordination work while maintaining existing project schedules.

Approaches to budget control are separated into three main actions:

1. Continuous cost monitoring during the DD phase
2. Value engineering exercises identifying cost-saving opportunities
3. Alternative material research to preserve design intent at a reduced construction cost

The establishment of cost reporting systems helps keep clients informed about the potential budget implications of design decisions while preventing budget overruns down the line.

Risk mitigation planning is a preventive measure that also has its place when it comes to dealing with timeline and budget considerations, as it is used to identify common DD challenges and develop response strategies for them. Technical risk assessment, schedule contingency planning, and the allocation of budget reserves are just a few examples of how preventive planning is used to resolve a lot of issues before they even arise.

Comparison table for common DD challenges

The most common challenges in DD include client-driven scope changes, technical coordination issues, and timeline pressure that intensifies along with increasing design complexity. The table below presents some examples of such challenges.

Streamlining design development with Revizto

Solutions like Revizto help to transform design development coordination by providing a centralized platform where architects, engineers, and consultants can collaborate in real-time using shared 3D models. This cloud-based solution can address the most common challenges of DD by tracking issue resolution, centralizing communication, and maintaining coordinated project documentation.

Traditional DD coordination relies a lot on fragmented workflows that involve multiple software platforms, email chains, and infrequent coordination meetings that commonly miss critical conflicts. Revizto helps eliminate these inefficiencies by creating a single source of truth where all project stakeholders can identify issues, provide solutions, and track job progress in real-time.

How Revizto enhances collaboration in the DD phase

The collaborative environment of Revizto assists design teams in working more efficiently during the critical DD coordination period, offering integrated tools for issue tracking, model coordination, and communication management. The platform works with all major file formats in the industry, including traditional 2D drawings, the commonly accepted Industry Foundation Classes (IFC) format, and the proprietary formats of popular architectural tools like Autodesk Revit, Graphisoft ArchiCAD, and SketchUp.

The key collaboration features of the platform include:

• 3D model viewing with markup capabilities
• Automated clash detection
• Integrated communication tools

Multi-disciplinary integration enables architects, structural engineers, mechanical, engineering, and plumbing (MEP) consultants, and specialty contractors to contribute their expertise in the same shared workspace. The platform’s issue assignment and tracking features ensure that coordination problems are addressed by the appropriate team members and resolved within project deadlines.

Real-time resolution and model coordination

Revizto’s issue resolution system streamlines the DD coordination process by offering structured workflows for not just identifying issues, but also developing solutions for them and tracking the progress of resolution. This is a systematic approach that prevents coordination issues from being overlooked while enforcing accountability among team members.

Issue identification tools help team members mark the specific locations within 3D models where coordination problems exist, attach relevant documentation or other materials, and assign responsibility for resolution to a specific expert or team. Priority classification systems help teams focus on the most problematic issues above all else while also maintaining awareness of all coordination requirements.

Features for the development of solutions allow team members to propose multiple approaches to resolution, compare alternatives within the 3D environment, and even document the rationale behind each solution. Progress tracking capabilities offer real-time visibility into the status of coordination for project managers, which is great for identifying potential delays and allocating resources accordingly.

Summary & key takeaways

• Design development transforms schematic ideas into detailed technical plans to enable accurate cost estimation and the preparation of construction documents.
• The successful coordination of DD relies on systematic workflows and clear communication protocols between architects, engineers, and specialty consultants working on the same interconnected building systems.
• The DD phase is the de-facto last opportunity to make major design changes without a substantial effect on project costs or construction schedules.
• Digital collaboration tools and BIM platforms have changed DD coordination drastically by enabling the detection and resolution of conflicts in real-time.
• Common DD challenges include timeline pressures, client-driven scope changes, and technical coordination conflicts, all of which need to be proactively managed for successful resolution.
• Solutions like Revizto help streamline DD coordination by offering a unified platform where all project stakeholders are able to collaborate in real-time, track issue resolution, and maintain coordinated documentation.

Frequently asked questions

What tools or software applications are commonly used during the design development phase?

The most common DD tools include building information modeling platforms such as Autodesk Revit, Graphisoft ArchiCAD, Revizto, or Vectorworks, which enable real-time coordination between architects and engineers in the same shared digital models. Other essential capabilities in software for design development include clash detection, cloud-based collaboration for file sharing, and dedicated engineering capabilities for designing structural, mechanical, or electrical systems.

How do client decisions impact the design development timeline?

The impact of client decisions on the design development timeline often results in delays that can drastically increase DD timelines because of how each approval checkpoint affects subsequent coordination work between architects, engineers, and consultants, all of whom must wait for direction before proceeding with technical development. Effective DD project management necessitates the establishment of clear decision deadlines and approval milestones early on, with contingency time being built into schedules to accommodate typical client review and decision-making processes.

What happens if major changes are needed after the DD phase is complete?

Major changes after the completion of DD require extensive re-coordination between all building disciplines, resulting in significant additional design fees and schedule delays in most cases. All the integrated technical work must be revised and re-approved by all consultants at that point, which is why most architectural contracts include change order provisions that allow architects to charge extra fees for scope modifications after DD approval (making it the single most expensive time to implement major design changes before construction begins).