House Extensions
Single & two-storey extensions that transform how your family lives.
Builders Plymouth · Est. South West
Premium builds.
Plymouth-built.
MAG Developments SW deliver house extensions, loft & garage conversions, renovations and bespoke new builds across Plymouth and the South West — to a standard you can stand behind.
Rated 5.0 from local Plymouth homeowners
Free consultation
Tell us about your project
- Fully Insured
- Building Regs Approved
- 30+ Yrs Combined Experience
- 12-Month Workmanship Warranty
- Same-Day Reply
Reviews
What Plymouth homeowners say
5 customer reviews
Yell
"The team at MAG have just finished a garage conversion for us. The team were all very friendly and worked to understand what we wanted and delivered. Due to holiday and work, the team got on with the job hassle free. The end product is fantastic and we are very happy with the job. Would highly recommend these guys!"
PeteW-305
Plymouth · Garage Conversion
Yell
"Loft Conversion – Excellent Work! We're absolutely delighted with the loft conversion completed by MAG Developments. From the very beginning, the team were professional, respectful, and incredibly tidy—always leaving the site clean at the end of each day. The quality of their work is outstanding and finished to a very high standard. They showed great attention to detail and clearly take pride in what they do. Communication was excellent throughout, and they genuinely went above and beyond to make sure we were happy at every stage. Customer care was second to none, and it was clear that our satisfaction was a top priority. We highly recommend MAG Developments and wouldn't hesitate to use them again in the future. OUTSTANDING in EVERY way."
DsM-6
Plymouth · Loft Conversion
What we do
Building services in Plymouth, done properly.
Whether it's an extension, a conversion or a complete new build — we handle every stage in-house with our trusted team.
All servicesLoft Conversions
Dormer, hip-to-gable and Velux conversions adding bedrooms and value.
Garage Conversions
Turn unused garage space into a home office, gym or annexe.
Renovations
Full property refurbishments — structural, kitchens, bathrooms, finishes.
New Builds
Bespoke new build homes from foundations to handover.
Project Management
We coordinate trades, planning and Building Control end-to-end.
About MAG
A trusted, established Plymouth building company.
Based in Plymouth, MAG Developments SW Ltd brings together over 30 years of combined experience in residential construction. We're known for craftsmanship, clear communication, and projects delivered on time, on budget and to a standard our customers gladly recommend.
30+ years combined experience
Fully insured & qualified team
Transparent, fixed-price quotes
Planning & Building Regs handled
12-month workmanship warranty
Trusted across PL postcodes
30+
Years combined experience
100%
Insured & accredited
12mo
Workmanship warranty
PL
Plymouth-based team
Recent work
Featured Plymouth projects
Areas covered
Building across Plymouth & the South Hams
PlymouthPlymptonPlymstockMannameadCrownhillSaltashIvybridgeTavistockSouth Hams
What areas do you cover?+
We are based in Plymouth and work throughout PL postcodes including Plympton, Plymstock, Saltash, Tavistock, Ivybridge and the wider South Hams.
Are you fully insured?+
Yes - MAG Developments SW Ltd carries full public liability and contractors all-risk insurance. Documentation is available on request.
Do you handle planning and building regs?+
Absolutely. We can manage the entire process including architectural drawings, planning applications, structural calcs and Building Control sign-off.
How long does a typical extension take?+
A single-storey rear extension typically runs 10-14 weeks on site once foundations begin. We provide a detailed programme with every quote.
Do you offer free quotes?+
Yes - we provide a free initial consultation and a fully itemised written quotation with no obligation.
Can you work to a fixed price?+
Most of our projects are quoted on a fixed-price basis once the spec and drawings are finalised. Variations are agreed in writing before any extra work.
Do you guarantee your work?+
All our work carries a 12-month workmanship warranty, plus manufacturer warranties on all materials and installations.
What sets MAG apart?+
Over 30 years combined experience, a small directly-employed core team, transparent pricing, and a genuine commitment to the build quality you would want in your own home.
Start your project
Ready to build with confidence?
Send us your plans, sketches or just an idea. We'll come back with honest advice and a clear, itemised quote — no obligation.