How to Project Manage Your Own House Extension: A Step-by-Step Guide

Thinking about extending your home? Managing the project yourself could save you thousands!

Hiring a general builder to oversee your extension might seem like the easiest option, but it often comes with high markups, limited control, and hidden costs. By taking charge of your own project—with expert guidance—you can stay in control, ensure quality, and save up to 20% on total costs.

At Klyra, we help homeowners like you successfully manage their own builds with professional support every step of the way. Here’s how to project manage your own house extension and make your dream space a reality—without the stress!

Step 1: Define Your Project Scope & Budget

Before anything else, you need a clear plan for your extension. Ask yourself:

• What’s the purpose of the extension? (Extra bedroom, larger kitchen, home office?)

• How much can you realistically spend? (Factor in materials, labour and a contingency fund)

• Will your project require planning permission or permitted development?

• Do you need an architect, structural engineer, or planning consultant?

  
  

💡 Expert Tip: Set aside 10-15% of your budget as a contingency fund for unexpected costs.

Step 2: Get Your Design & Permissions in Place

Once you’ve defined your goals, it’s time to turn your vision into a solid plan.

• Work with an architect to create detailed drawings and ensure your extension meets building regulations.

• If required, submit a planning application to your local authority. (Some extensions qualify for permitted development—check before applying!)

• Get structural calculations from an engineer if your project involves load-bearing walls or foundations.

• Apply for a building control inspection—this ensures work is compliant at key stages.

  
  

💡 Expert Tip: Not all builders follow regulations closely! Managing your own project means you can ensure every step is done legally and safely.

Step 3: Find & Manage Contractors

You’ll need trusted professionals for specific tasks, such as:

• Groundworks & Foundations – Laying a solid base for your extension.

• Bricklayers & Builders – Constructing the walls and structural elements.

• Electricians & Plumbers – Installing utilities safely and efficiently.

• Roofers & Joiners – Finishing the structure before moving to interiors.

  
  

How to Hire the Right Contractors:

• Get at least three quotes for each trade to compare pricing and quality.

• Check their experience, insurance, and previous projects.

• Agree on fixed-price contracts to avoid surprise costs.

• Schedule work efficiently to prevent delays (e.g., don’t book plasterers before electricians finish wiring).

  
  

💡 Expert Tip: Some builders add 20-30% markups to subcontractor costs—by hiring directly, you keep that money in your pocket.

Step 4: Manage the Budget & Keep Costs Under Control

When project managing your own extension, staying on top of finances is crucial:

• Track all costs – Keep a spreadsheet with quotes, invoices & payments.

• Source materials yourself – Builders often mark up materials—buying direct can save you thousands!

• Stage payments correctly – Never pay everything upfront; agree on payments based on completed work.

• Stick to the plan! – Late design changes can increase costs & delay your project.

  
  

💡 Expert Tip: Many homeowners overpay due to poor planning—we help clients avoid these mistakes and stay within budget.

Step 5: Oversee Work & Quality Control

Even the best tradespeople make mistakes, so you’ll need to check work regularly:

• Compare progress to your architectural plans – Ensure walls, doors, and windows are positioned correctly.

• Use a snagging list – Note any issues early to prevent costly fixes later.

• Schedule building control inspections – These are required at key stages to approve work.

• Communicate clearly with contractors – Regular site visits help avoid misunderstandings and rework.

  
  

💡 Expert Tip: Most costly mistakes happen due to lack of supervision—stay involved to keep things running smoothly!

Step 6: Completion & Final Checks

Before you celebrate your finished extension, make sure you:

• Review all work against your contract – Any incomplete jobs? Raise them now!

• Get all compliance certificates – Electrical safety, gas installation, and building control sign-offs.

• Complete a final snagging list – Ensure all minor fixes are addressed before final payments.

• Keep a record of warranties & receipts – Useful for future repairs or resale value.

  
  

💡 Expert Tip: General builders often rush the final stage—when managing your own project, you can ensure everything is completed to your standards.

Ready to Take Control of Your Build? We’re Here to Help!

Managing your own house extension might seem overwhelming, but with expert guidance, you can do it!

At Klyra, we provide:

• Step-by-step project planning tailored to your build.

• Budgeting support to help you save money & avoid hidden costs.

• Contractor coordination advice to ensure high-quality work.

• Virtual guidance at every stage so you’re never left guessing.

  
  

Book a Consultation Today to get started!