Jonathan Freegard Architects are delighted to recommend Mariusz Gawecki and his team at GBG Building Services who have just completed a high-end residential refurbishment for our clients under our direction in Hampstead, North London. The job has been executed to a very high standard, on time and on budget. The planning and programming of the work have been exemplary and the building team has been helpful, obliging and considerate to the neighbours throughout. The team members have brought their own considerable skills to the construction process and interpreted our design intentions with intelligence. It has been a pleasure to work with them.


We recently had our St John`s Wood apartment in a Grade 2 listed building renovated by GBG. They have done a stunning job in terms of both finish and service, the only downfall was the timing due mostly to unforeseen issues with the old nature of the building and the tight spaces within which they had to work.

We had quite a bit of work done, with a mezzanine being installed, the bathrooms rebuilt, kitchen renovated, access to 2 office/spare rooms built and much more. They constructed and installed inbuilt wardrobes and storage as well as designed the inbuilt desks for the offices, and the trapdoor access to the offices.

Our build definitely would not have turned out as amazing as it had without them as they did much more than just build, they helped design and used a lot of common sense when they were under time pressure and didn’t have/ couldn’t get guidance from us.

We will be using them again when the time arises, and would definitely recommend them to anyone who is looking for a builder with an eye for quality and design.

Sonya & Daniel

GBGBuilding Services have been employed by us to carry out general contracting and specialist sub- contractor services on a number of projects, over the past four years. These have included The Paddington London Hilton, The Millennium Mayfair Hotel Grosvenor Square, and the Royal Automobile Club Piccadilly and have ranged in value from L50k – L1.4 m.

Their approach to the works at all levels has been both helpful and highly professional, their craftsmen, tradesmen and management, working with our own team to provide a finish to the highest of standards, very often within extremely tight constraints on both programme and finance.

I believe the company has grown in stature over the years we have been working together and is quickly becoming a name within the industry that companies like ourselves can respect and rely on, to carry out larger and even more prestigious projects in the future.

Senior Projects Manager

Mariusz and the team at GBG delivered a complex and comprehensive redevelopment project in Fulham that exceeded expectations. Mariusz was given a very restricted time frame and a challenging specification but he pulled together the resources needed to complete the project on time. Mariusz is very intelligent, trustworthy and creative. I would not hesitate to hire him again for similar or larger projects

Stephen & Joanna

Mariusz and GBG Building Services did an excellent job on my total internal renovation of a 2-bed period maisonette in Hampstead. The project included a complete stripping back to the bare brick walls, changing internal layout and completely rebuilding the interiors. Mariusz and his team were responsible for the full build, including all decoration and joinery works. While some (other) aspects of the project were challenging, GBG were a pleasure to deal with throughout. The team were thoroughly professional, completed on time, and have delivered a very high standard of finish (I have had it complimented by others who have much more experience of building projects than I..!). Mariusz and site manager Eric have a strong work ethic and run a tight ship, and they have gathered a team around them that are polite, diligent and capable. Never once did I see a mess left on site – everything was kept ship shape and tidy throughout the 5 months, and my neighbours have expressly told me how impressed they were with how little disturbance there was. (Never a stray cigarette butt in the shared garden!)

For me this was my first major building project, and I’m delighted to say that my experience with GBG was nothing like the horror stories I’d heard about builders from friends and colleagues. Quite the opposite: at challenging times during the project GBG were a huge help and went the extra mile to help the project succeed. I warmly recommend them.


We (a small interior design partnership) have recently worked with GBG Building Services (alongside Jonathan Freegard Architects, who we would also recommend). The project involved converting two very dilapidated flats, on different levels, into one high end fully reconfigured/renovated flat. The work was complex, not least because it is a Georgian building with difficult access. Mariusz, Eric and the team delivered the project on time, on budget and to an exceptionally high standard. In our experience this is rare.

Working with a contractor for the first time is always a learning curve on both sides. We were pleased to find that Mariusz’s approach is very much in the spirit of collaboration. Our attention to detail does not make for an easy ride for a builder, Mariusz was patient and understanding about this. However, it’s the fact that he cares enormously about whether the client is happy, and his determination to deliver quality that makes him stand out. He is intelligent, motivated, responsible, entirely trustworthy and generally a pleasure to deal with.

The pace of the work and involved nature of the design meant there was the inevitable odd minor mistake (on all sides). However, in our view the sign of a good builder is their willingness to rectify things, and the grace with which they do this. Mariusz scored highly on both fronts. There are so many things to commend about the team – they turn up on time, work very hard, are considerate, skilled and it’s a tidy and professionally run site. As a result, there were none of the common complaints from neighbours or our client. Mariusz prefers to keep almost everything under his umbrella, and can provide an extensive range of services. This comes at a premium, which our client was aware of from the start, but he made the decision that the benefits were worth the extra cost. He is delighted with the results, which have far exceeded his expectations.

Michelle & Claudia Jarman

May we take this opportunity to thank you at GBG for the works undertaken at the house we now enjoy.

From the initial contact through consultations, quote and actual works, we have been pleasantly surprised at the total involvement, advice, creativity and shear hard work that has been put into the project by GBG. This includes meeting budgets and timing. At no time did we have any concerns with GBG acting as project managers, especially with the exceptional liaison experienced throughout.

Again may we thank all who worked on the refurbishment for the beautiful home we now have.”

June & Chris

Hi Mariusz,

I want to take the opportunity of thanking you and Eric for the work you completed on my house.
The soundproofing project was extremely complex and as you know I obtained several quotes from established building firms before I decided to go with you .

The result has been frankly truly amazing, way beyond my expectations and even though it was expensive was worth every penny. I also was delighted the project was completed on time and on budget. The wardrobes really add to the bedrooms and my tenants whom you know have the highest standards are delighted with them also. I would have absolutely no hesitation in recommending you to any potential future clients and would be happy for you to show this e-mail if you wish.