GT Building Design

Home Extensions & Architectural Design

Celebrating 40 years of architectural excellence.

Transform your home with clear advice, practical solutions and personal service from Glenn Thompson, a Chartered Architectural Technologist specialising in domestic extensions, alterations, loft conversions and garage conversions across Northern Ireland.

Contact Glenn

Glenn is ready to assist you. Click the button below for advice, support, or to request a quotation.

Contact Glenn

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About GT Building Design

GT Building Design is a Chartered Architectural Practice based in Donaghadee, founded in 2004 and led by Glenn Thompson MCIAT.

With over 40 years’ experience in residential architecture, Glenn provides homeowners with creative, cost‑aware and achievable design solutions — guiding you from first ideas through planning permission, building control approval and construction.

Every project is handled personally, ensuring clarity, continuity and a design approach tailored to your home and lifestyle.

Why Choose GT Building Design

Clear advice. Practical solutions. Personal service.

Personal involvement from start to finish
Your project is managed directly by Glenn, ensuring consistent communication and a smooth process.

Chartered Architectural Practice
Professional, compliant and committed to the highest technical standards.

40 years’ residential expertise
Specialist in extensions, renovations, loft conversions and garage conversions.

Local planning & building control knowledge
Extensive experience with councils and regulations across Northern Ireland.

Transparent pricing
Clear, written fee proposals with no hidden costs.

Creative, achievable design
Designs that enhance your home while remaining practical, buildable and budget‑aware.

Contact Glenn

If you’re planning a home extension, renovation or conversion, Glenn is ready to help.

Contact Glenn

Your Achitectural Design Process

1. Introductory Telephone Consultation

A friendly call to discuss your ideas and provide early architectural advice.

2. Detailed Written Fee Proposal

A clear proposal outlining all fees, stages and expected costs.

3. Measured Survey & Existing Drawings

Accurate on‑site measurements followed by professionally drafted drawings.

4. Bespoke Design Proposals

Tailored design options based on your needs, lifestyle and budget.

6. Planning Permission & Building Control Approval

Full preparation and submission of all drawings and documents required.

What Clients Say

Allwyn Corrin

Within a tight time frame Glenn worked quickly and efficiently to draw up plans for a beautifully designed extension to my bungalow. He was very professional, patient and helpful at all times, dealing promptly with any queries. He kept me informed throughout the whole process, and I was really delighted with his service.

Awards & Recognition

Recognised for excellence in residential architecture across Northern Ireland:

Best Residential Extensions & Conversions

Architecture Company Northern Ireland

Most Trusted Residential Architecture Practice 2025

Best Architectural Technologist Northern Ireland

& Residential Architecture Studio of the Year 2024