Avoid These 7 Design and Build Disasters

When You Start a Project, You Have Two Main Options

When it comes to delivering a residential building project—whether it’s an extension, renovation or full new build—there are two common procurement routes:

• Traditional procurement, where design and construction are kept separate
• Design and build (D&B), where one contractor handles everything

There are other models too, but for most homeowners, it comes down to choosing one of these. And while each has its pros and cons, one route is increasingly leading to serious problems in the domestic sector.

What Is Design and Build?

Design and build (D&B) is a procurement route where a single contractor takes responsibility for both the design and construction of your project—under one contract.

Instead of the client appointing an architect or designer directly, the builder assembles their own team of consultants. This might include architectural, structural, and other design inputs, but all under the builder’s control—not yours.

On the surface, this looks attractive: one point of contact, one timeline, one price. But in practice, especially in the domestic sector, it comes with major risks.

Pros of Design and Build

• Single Point of Contact – One company handles everything
• Potentially Faster Delivery – Design and build can overlap, reducing programme time
• Early Cost Certainty – Budget estimates are provided early in the process
• Builder Coordination – The contractor is contractually responsible for design errors and delivery—in theory

Cons of Design and Build

• No Independent Oversight – The builder marks their own homework – are builders overcharging
• Design Quality Is Often Poor – Prioritised for ease of construction, not performance or aesthetics
• Lack of Cost Transparency – Bundled pricing, vague exclusions, and hidden extras
• No Competitive Tendering – So you don’t know if you’re overpaying (and many do)
• Limited Flexibility – Changes after signing are difficult and expensive
• Decisions Made On-Site – Lighting, layouts, and key design features are often guessed

What Is Traditional Procurement?

Traditional procurement—also called design–tender–build—is the most robust and accountable route for residential projects.

How It Works.

1. The client appoints an architect or technologist to design the project fully
2. The design is tendered to multiple builders for competitive pricing
3. A builder is appointed under contract, and the designer stays involved during construction to oversee quality

This separation of duties keeps checks and balances in place, meaning design quality is protected and construction is properly managed.

Pros of Traditional Procurement

• Independent Design Quality – Focused entirely on the client’s needs
• Transparent Pricing – Builders quote against the same detailed drawings
• Oversight – Your designer checks the work, identifies defects, and manages risk
• Flexibility Before Build – Proper time for value engineering and changes
• Contractual Protection – Includes staged payments, retention, defects period
• Retention and Snagging – Payments held back until completion is verified

Cons of Traditional Procurement

• Takes Longer Upfront – Sequential process requires more planning time
• Client Needs to Stay Involved – More decisions to make (but with expert help)
• Multiple Contracts – You’ll separately appoint a designer and builder

Why Working Drawings Are Crucial for Pricing & Construction

Why Design and Build Is Failing Domestic Clients

While Design and Build can work on large commercial or residential schemes—with in-house design teams, proper drawings, and a QS tracking value—it’s often completely misused in domestic settings.

Builders promise a “streamlined” experience and a “fixed price”, but the reality looks more like this:

Disaster 1: Design Is an Afterthought

Design is rushed, incomplete, or reduced to the minimum needed for planning. There’s no thought for layout, lighting, circulation, or technical compliance.

Disaster 2: Lighting and Services Are Guessed

Unlike a commercial scheme with coordinated M&E layouts, many domestic D&B projects guess lighting positions and services on site. It shows.

Disaster 3: No Oversight Means No Accountability

Without an architect, technologist or contract administrator checking the build, there’s no one protecting the client or catching poor workmanship.

Disaster 4: “Fixed Price” Rarely Means Fixed

Many quotes are intentionally vague, with major exclusions like groundwork, steelwork, or finishes quietly pushed to later as “extras”.

Disaster 5: Budgeting Is Nonexistent

Builders often spend client money with no plan. There’s no QS, no structured procurement, and no incentive to save. Clients end up overpaying with no idea where the money went.

Disaster 6: You Can’t Compare Costs

There’s no competitive tender, so you don’t know if the quote is fair. Builders set their own price, and you’re locked in.

We’ve seen D&B quotes that were £240,000 higher than necessary—with no added value.

Disaster 7: It Lacks the Professionalism Found in Commercial Projects

In commercial D&B, proper design teams are engaged. Drawings are coordinated. Lighting isn’t guessed. Costs are reviewed by a QS. Domestic D&B rarely works this way—and clients pay the price.

So Which Route Is Best?

That depends on the project type and team involved.

• Design and Build can work at scale, where the contractor runs a professional internal design team and there’s proper process.
• But for domestic projects, Design and Build is increasingly misused—resulting in poor design, inflated costs, and frustrated clients. – Dont get overcharged use our builder review service before you start construction

Smaller projects actually need more external input, not less. There’s less room for error, and less money to fix it if things go wrong.

How to Protect Yourself

If you’re planning a home extension, renovation or new build:

1. Get independent design advice before speaking to builders
2. Don’t settle for planning drawings—ask for full technical detailing
3. Use a qualified professional to oversee the build
4. Demand itemised quotes and proper contracts
5. Hold back final payment until all works and snagging are completed

5 Powerful Truths About Clients, Architects & Builders

Summary: The Key Benefits of Traditional Procurement

• Independent, client-led design
• Transparent, competitive pricing
• Expert oversight on site
• Flexibility and better build quality
• Proper control of payments and snagging

RIBA Plan of Work 2020 overview

Final Thoughts

Design and build has its place—but that place is not in most domestic residential projects.

It may promise convenience, but too often, it delivers poor design, poor quality, and poor value. If you’re about to spend tens or hundreds of thousands on your home—don’t gamble it on promises.

Get it designed properly. Get it tendered properly. And get it built with the right people protecting your investment every step of the way.

See how our architectural services can assist your project requirements.