Here are some testimonials from some of our clients. You can see examples of our sash window installations on the Window Gallery page.


Mark and his team came to restore, draught proof some of our sash windows and replace some sills. They were extremely efficient, tidy and actually finished ahead of schedule, the quality of work is great, delivering exactly what they had promised. Mark and his team provide a great service in a timely fashion, I would not hesitate to work with him again.”

Ray Loke
Old Park Road, N13 4RG

Mark replaced four windows in our Edwardian house and renovated a number of others. Previous owners had taken out the original sashes and replaced them with hideous louver windows. Mark restored the original sash windows to match those downstairs. He didn’t cut any corners, but replicated exactly the original curve on the top panes. He offered a very efficient service in an extremely courteous manner, as did all his workmen. He was very clear as to costs. All the team were very pleasant and did their utmost to keep the mess to a minimum. I would have no hesitation in recommending Mark.”

Angela and Evelyn
Linzee Rd, N8 7RE

North London Box Sash have changed all the windows in my Victorian property.
Throughout the process i.e. estimate, measuring and commencing the work Mark arrived/started at the agreed times. Mark’s team were professional and took great care with their work, cleaning before leaving each evening. The windows are exact replicas of those removed. I would recommend this company to anyone thinking of replacing their Windows.”

Joyce Collison
Church Hill, N21 1LS

We have been very pleased with our new windows. Mark and his team have been very professional throughout. Mark was well informed about all the period details and constructed the windows to a high standard of craftsmanship. When putting the windows in – Mark and his team were very courteous and professional and delivered bang on time. I would have no hesitation in recommending Mark and indeed using him again for other windows and door replacements.”

Giovanna and David Newson
Radcliffe Rd, N21 7SD

After a bad experience with another company we came across Mark at North London Box Sash. He was very polite and knowledgeable. He answered all of our questions thoroughly and put our minds at ease from day one.

Mark reconditioned and double glazed around 11 of our sash windows which were in a bad state and they all look brand new now and it has made a remarkable difference. The house is a lot warmer and the windows are now easy to open and close.

Mark and his team worked efficiently and tidied up at the end of the day. We have recommended him to many of our friends who have also been very happy with him. Thank you again and we are so glad we found you!”

Eileen Hewett
Osbaldeston Rd, N16 6NJ

I used North London Box Sash to replace existing double windows which were faced with some very old fashioned and inferior secondary glazing. Mark and his team were quick and efficient, moving things out of the way, covering surfaces with dust sheets, removing rubbish and putting everything back in place afterwards. I was very pleased with the finished work and, now that colder weather has arrived, the new windows seem to be doing the job of keeping me warm.”

Ann S
Dukes Avenue, N10 2PU

We’re very happy with our new windows. We considered a number of options, and North London Box Sash gave a competitive quote for a good quality set of windows. We now have lovely double glazed draught-free sash windows, which also block out the noise from the road. I would recommend Mark and his team.”

Aditi Mene
Muswell Hill Place, N10 3RP

I have used Mark and his team twice now as I was very impressed with initial large box sash fittings, especially the quality of the windows provided, the attention to detail and professional finish of the work, as well as being competitive on price. The work was well organized and completed in a single day on both occasions with my property left in a clean and tidy state. Adding double glazed windows throughout the property has made a huge difference. I would highly recommend the company to anyone.”

Jerome and Elena
Milton Grove, N16 8QY

We would highly recommend North London Box Sash. Mark and his team did an excellent job replacing our old sash windows. The results are better than expected. The new windows have made a real difference to insulation and have significantly reduced the noise from the busy road we live on. We are very happy with the work carried out and the efficiency and professionalism of Mark and his team.”

Joanna & Peter Bennett
Page Green Terrace, N15 4NU

I have been really impressed by Mark and his company’s management of replacing my living room sash windows. Everything was dealt with in a straight forward, knowledgeable and helpful manner and most importantly the windows look great and have made such a huge difference. I was equally impressed with the painting of the window and the re decorating/touch up of the room. I would be happy to recommend Mark and his company’s work and should I need any further work done on the rest of my property will know who to call.”

Jo Redfurn
Albert Rd, N22 7AH

Mark at North London Box Sash was very helpful in describing the various options. On the day of the work, he and his colleagues were prompt, tidy and left us with excellent products – draft proof windows in one room, and a new double glazed window in another. Ian the painter arrived a few days later and we now have a fine looking new window, and much warmer, quieter rooms”

Megan Davies
Hardwick Rd N13 4SG

I was very impressed with Mark and North London Box Sash from the outset.

Mark was incredibly professional from start to finish. He gave a clear and competitive quote, and was able to schedule in the start of works very quickly.

The Team that worked on the windows were very competent, polite and friendly. They worked at speed, but at the end of each day always left the rooms they were working in tidy and clean. This was very important for us, as we have two young boys so wanted the least upheaval while the works were going on, as well as a safe environment.

The window frames themselves were of very high quality and have transformed the facade of our house. We are delighted with the finished product and cannot recommend Mark and his team highly enough”

Sophie Spinoza
The Crest N13 5JT

North London Box Sash – I am very pleased with my new windows. Efficient and considerate, North London Box Sash delivered and fitted on time as planned, yet were flexible in working around time and other constraints which cropped up.Thanks so much!”

Sheila Blankfireld
Raleigh Rd, N8 0JB

It’s always a pleasure to find somebody in the building trade who is both a perfectionist and able to deliver on time and to schedule. Mark built 7 box sash windows and a hardwood window for us. The quality of his work is outstanding, and the windows have completely transformed our home. Mark is easy to communicate with, extremely reliable, a consummate professional and we would recommend him highly. He is very knowledgeable about carpentry in general and has been really helpful in giving us advice. We have really enjoyed working Mark and his team”

Aidan Hamade
Uplands Rd, N8 9NN

Mark is very professional and his work is of excellent quality. My new double-glased sashes were delivered on time and installed into the existing frame trouble-free. I couldn’t be happier with the result.”


Mark did a great job for us. Replacing our window was a lot of work, but he arranged everything for us. He used quality materials and the result looks excellent – it’s transformed the whole room.”

Michael Halsworth
Seaford Road N15 5DU

I recommend North London Box Sash without reservation. Mark is experienced and knowledgeable and is someone who takes a pride in his work. He and his team were polite and efficient and did an excellent job replacing our old sashes with double glazed ones. The work was carried out with fine attention to detail and care for the existing Victorian features. It has also made a big difference to our comfort. I used 2 companies to do the work on our windows but without doubt would only use NLBS if I were to have the work done again”

Roger Cauthery
Inderwick Rd N8 9JY



A very kind thank you to all of our customers that have sent their testimonials, we are extremely grateful.