SIP Granny Annexes & Garden Rooms Built for Year-Round Living
Custom-built granny annexes, garden rooms and modular buildings designed for comfort, performance and long-term use across Hertfordshire, North London and surrounding areas.
Specialists in Granny Annexes & Garden Buildings
At TRJ Construction Ltd, we specialise in designing and building high-performance SIP granny annexes and garden rooms tailored to each client’s needs.
Our buildings are fully insulated, structurally robust and designed for year-round living, making them ideal for independent accommodation, home offices or additional living space.
• SIP panel construction
• Fully insulated buildings
• Kitchens and bathrooms included
• Built for year-round use
Why Choose TRJ Construction
We focus on quality construction, practical design and long-term performance.
Our SIP buildings provide excellent insulation, structural strength and energy efficiency, making them ideal for modern living spaces.
Every project is tailored to the client, ensuring the final building meets both functional and aesthetic requirements.
• Over 20 years of construction experience
• SIP panel specialist
• Fully bespoke designs
• Turnkey service from design to build
• Built to building regulations standards
Over 20 years of construction experience delivering high-quality SIP buildings across Hertfordshire and North London.
Self-contained garden annexes designed for independent living with kitchen, bathroom and full insulation.
Modern garden rooms for offices, studios and leisure spaces, built for comfort all year round.
Guidance and support through the planning process, including drawings and applications.
Compact and fully equipped kitchen designs tailored for annexe living.
Functional and modern bathroom solutions including wet rooms and drainage systems.
Modern air conditioning systems designed to provide reliable cooling and heating for garden rooms, annexes and extensions.
Explore some of our completed granny annexes and garden rooms, built using high-quality materials and SIP construction methods.
Designing a granny annexe involves careful planning, from layout and insulation to kitchens, bathrooms and drainage systems.
We provide guidance at every stage to ensure your building meets planning requirements and delivers comfort throughout the year.
Expert guidance through planning permission, drawings, and approvals — making your project smooth and stress-free.
Smart, space-efficient kitchen designs tailored for annexe living, combining functionality with modern style.
Modern bathrooms and shower rooms designed for comfort, practicality, and efficient use of space.
Full building control support from start to finish, ensuring your project meets all regulations, inspections, and compliance requirements.
Looking to build a granny annexe, garden room or extension?
Speak with TRJ Construction Ltd today and start your project with expert guidance.
We take pride in delivering high-quality granny annexes and garden buildings tailored to each client’s needs. Our projects are built with care, precision and attention to detail, and we value the feedback we receive from homeowners who trust us with their space. Here’s what some of our clients have to say about working with TRJ Construction Ltd.
" Costi and his team have just finished a truly brilliant job on our new garden room. "
" The finished granny annexe was outstanding, really high quality fittings and a high standard of finish."
"Costi himself is very passionate about his work, suggesting some details on our build that make it so much better than we originally envisioned! "
Jessica Tenner
The gym looks absolutely amazing! It all went so smoothly and the guys were an absolute delight to have around.
Hannaford
I'm delighted with my studio! Many thanks for your invaluable input. Costi and his team have been great.
