Spectra Extensions
Traditional Finish. Built Smarter. Delivered in weeks, not months.
Our contractors are accredited by
The Spectra Range is purposely designed for single storey side and rear extensions that fall within permitted development — no planning permission needed.
Extend into your garden for a larger kitchen, open-plan living space, or family room.
Use unused side space for a utility room, home office, or to widen your kitchen.
Most single storey extensions qualify under PD — no planning application, no waiting, no uncertainty.
Advanced methods, traditional results. As experienced extension builders, we deliver house extensions indistinguishable from conventional builds — completed in 5-6 weeks with less disruption thanks to precision engineering and RADIX foundations.
Steel foundations installed in hours, not weeks. No concrete, no curing time, no excavation. Ready to build on immediately with less than 50% of the carbon footprint of traditional foundations.
Every Spectra Extension is uniquely designed by our structural engineers to maximise performance and quality. Superior U-values and less carbon than traditional builds.
Solid brick outer walls on a precision-engineered timber frame. Real brick that matches your existing property, with the speed and thermal advantages of modern construction.
See the quality of our work. Every project is built to the same exacting standards.
As local builders with years of experience, we combine modern construction technology with uncompromising quality standards. The result? Premium house extensions delivered faster, with less disruption.
Traditional extensions take 3-6 months. Our advanced process delivers in a fraction of the time.
Every element is chosen for performance and longevity. From foundations to finishes, we use materials trusted by commercial developers across Europe.
No concrete trucks blocking your drive. No excavators tearing up your garden. Our clean, efficient process respects your home and your time.
Your quoted price is confirmed in writing before work begins. No hidden extras, no cost creep — the price we quote is the price you pay, guaranteed.
Spectra Home Extensions is proudly operated by Crownhill Building Services, bringing years of construction expertise to every project. We combine our trusted local reputation with the latest building technologies.
Looking for a traditional extension or other building work? Visit our parent company Crownhill Building Services — home extension builders in Milton Keynes for our full range of services.
Real reviews from our parent company's Google Business Profile
We had some trepidation about undertaking building works but we needn’t have worried. Eric and his team worked extremely hard; they appeared every day and when they couldn’t make it we were notified …
Read more on GoogleWe used Crownhill Building for our two storey side and single storey rear extension. We are very happy with works carried out. Eric is very responsive and project managed the job well. His guys keep t…
Read more on GoogleReally great service and top quality craftsmanship
View on GoogleThe CBS have helped me to even floor upstairs. They have done it perfectly. The Eric and his team were very helpful, communication was on very good level, very recommended.
View on GoogleEric did a great job on my self-contained garage conversion, following the custom designs I requested. The work was done to a good standard, and he was professional and reliable throughout the process…
Read more on GoogleWe have recently completed our house extension project and are so pleased we chose CBS. The project was completed within timescales initially agreed. Their builders are so humble and always left the s…
Read more on GoogleIt was great working with Crown Building Service (CBS) throughout the extending our house process. They were easy to get in touch with and quick to respond to any questions that came up. The project m…
Read more on GoogleI engaged Crownhill to do major work on my ground-floor flat in CMK. At first I was worried, but there was no need. The result was excellent. Thank you.
View on GoogleWe selected crownhill building services for building a bedroom toilet and porch at our house and we are really happy with their work. They have very hardworking builders ,well organised with good time…
Read more on GoogleExtremely happy with the service that Eric and his team has provided on our extension/garage conversion. The builders were punctual, tidy and have a wealth of experience. Eric's communation was excell…
Read more on GoogleWe had a conservatory removed and extension built in it's place and a garage conversion. The work on completion exceeded our expectations and the team were great. Smooth process from start to finish
View on GoogleWe would highly recommend Crownhill building services if you are planning on having building works done. Our 4mtr long extension was done by Eric and his team and they made the whole project seamless…
Read more on GoogleI have known Eric for a number of years and on this occasion used his company to dismantle a conservatory for a rental property and make good internally and externally, the guys were careful and took …
Read more on GooglePlan your Milton Keynes home extension this spring with expert guidance on planning permission, costs and timelines from Spectra Extensions. Free consultation available.
Read MoreWorried about your garden during a home extension in MK? Spectra Extensions uses RADIX foundations — no excavation, no concrete, no mess. Trusted extension builders in Milton Keynes. Free site visit.
Read MoreImagine more space, more light, more life. Let's make it happen.
Get a free, no-obligation quote from trusted house extension builders in Milton Keynes. We'll visit your property and show you what's possible with a Spectra Range extension.
