property extensions & annexes

House extension builders in Cornwall

Wondering where to start with building your house extension or annexe?

Are you contemplating the idea of expanding your property with a new extension or annexe and are looking for the right choice of house extension builders in Cornwall? It’s easy to feel in a position where embarking on such a project at your home is both exciting and a bit daunting. Your main goal is to find a company that can address your requirements and turn your property expansion aspirations into a realistic, smooth process.

Feeling unsure?

What Challenges Can ModBox House & Home Extension Builders Solve for You?

When it comes to extending your property, the good news is that approached sensibly most local Planning authorities are open to the idea of expanding your home to accommodate additional living space.

The key to success is ensuring that the development remains in harmony with your existing structure and complements it rather than overpowering it. Additionally, there’s often flexibility when it comes to converting an existing integral garage into additional living space, which, in some cases, may not necessitate a new Planning consent.

When it comes to property extensions and annexes, it’s natural to have questions and concerns. Here’s how our expertise can address common issues you can experience:

Paying Fair Prices for Quality Work

Worried about ending up overpaying for house extension builders?


We understand the importance of fair pricing while delivering high-quality work. Our transparent pricing ensures you get the best value for your investment, without the concern of hidden costs. We explain the entire budgeting process clearly to you before your project commences. We work on your project as if it were our own, thinking from your point of view.

Comprehensive Build Management

Have you considered how to manage the build process effectively, including all aspects of the project beyond just appointing the building contractor?

Where we differ to a ‘normal’ builder is that we provide a comprehensive build management service, overseeing every aspect of your project to ensure a seamless and worry-free experience, right from Planning to completion. We understand you don’t do this all the time and take on the role of an experienced provider.

Navigating Planning Permission

Worried about the complexities of obtaining Planning permission for your property extension or annexe?

We have extensive experience in navigating the Planning process in Cornwall. Our expert house extension builders will guide you through the entire process, ensuring all necessary approvals are obtained, and your project complies with the relevant building regulations.

Full-Service Solutions, Including Utilities Concern:

We offer full-service solutions, ensuring that all essential utilities are properly set up and integrated into your property extension or annexe, sparing you hassle in providing a seamless experience.

Quality Materials and Craftsmanship

Are you concerned about what quality of materials may be used in your property extension or annexe project?

We prioritise the use of high-quality materials and craftsmanship in every aspect of your project. Our track record of home building reflects a commitment to quality and the environment that ensures your property extension or annexe stands the test of time. Please see our past projects page for example.

How Our Property Extensions & Annexes Can Benefit You

At ModBox Developments we specialise in creating exceptional property extensions and annexes in Cornwall. We manage every project from concept to completion, so you only need to appoint us as your trusted local building partner. Our services extend to areas including Rock, Polzeath, Mawgan Porth, and the surrounding areas of North Cornwall.

In Cornwall there is generally a favourable stance towards Planning for detached annexes, as long as certain criteria are met. These conditions include being subordinate in scale to the main dwelling, sharing access and services and with a reasonable requirement for construction to take place; for example, for an understandable family reason requiring additional space.

Discover how ModBox Developments’ property extensions and annexes offer solutions to your common concerns:


Our comprehensive consultation process allows us to fully grasp your vision and the specific requirements of your house extension or annexe project. With a shared vision in mind, we make sure that every element is carefully considered, ensuring the expansion of your property aligns with your aspirations.

Procurement & Planning

Procurement involves the process of acquiring the right materials and services under specific conditions and timelines to meet the needs of your house extension or annexe project. With decades of experience in procurement and the necessary approvals process, we streamline your house extension or annexe project. This is why we have become one of the top house extension builders in Cornwall.

Concept Design

Our highly skilled designers excel at crafting modern designs that turn your vision for your house extension or annexe into reality. We pay meticulous attention to detail, optimising the available space to provide a floor plan that perfectly suits your needs. Whether it's contemporary new-build architecture, thoughtful renovations, or innovative concept designs, we specialise in creating timeless, well-considered properties of the highest quality in Cornwall.

The Build

We take charge of the construction process, managing all the stages of your house extension or annexe project. This includes the construction of the frame, roof, exterior, and interior fittings, as well as drainage and external works. We keep you informed throughout the process, addressing any questions you may have along the way.


Right thorough to deep cleaning, before project sign-off, we ensure that every detail is meticulously prepared for the day you move into your extended property or annexe in Cornwall. We handle all the final touches, so you can enjoy a seamless transition as a high-quality house extension builder in Cornwall.

Craftsmanship and Dedication to Cornwall's Extensions and Annexes

Our passion lies in delivering luxurious extensions and annexes that accurately match your vision. Right from our initial discussions, we focus on your requirements and specifications, ensuring that we create contemporary spaces that align with your particular needs.

We deliberately limit the number of projects we undertake simultaneously, allowing us to maintain an exceptionally high level of attention to detail for every extension or annexe we build. Our goal is to provide you with the confidence that your project will benefit from the collective commitment and focus of our experienced team. With our extensive local experience, you can trust us to deliver outstanding results

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