Core Sash Windows

We have had 7 windows replaced by Core Sash Windows, and are absolutely delighted with the work they have done for us. From our initial appointment with Ryan to the actual work days with the window installer (Irmis) and the painter (Andrew), everything has gone smoothly without a hitch. The quality and cleanliness of the work, as well as their professionalism exceeded our expectations. We would warmly recommend them!

I live in a listed building so our design constraints are very tight. I'm very pleased with the service and the product. Incredible work from the whole team! Some mistakes were done at the start but what really matters is how well they dealt with it. It's an honest business that cares about their customers. I'll surely be using their services again.

Had new French Doors installed and the fitters were efficient, took great care to isolate disruption and cleaned up perfectly. The decorator who came the next day was meticulous and again left no mess at all. Not all companies will make good and redecorate around their work like this.

Tim and the team were professional, efficient and responsive. They were flexible with our schedule and we very really impressed with the quality of their work. Highly recommended.

Throughout the process everyone we met and spoke to were knowledgeable, professional and completed the work to a very high standard. Responsive and friendly from start to finish. The window itself was fitted and finished neatly, work was very tidy and quick, and looks great! Would definitely recommend.

I could not have asked for a better outcome when having full box replacements for my sash windows (based in London Fields, Hackney). Work was carried out to a high standard, efficiently and throughout installation the property was kept clean and protected from the risk of dust and potential damage. Special thanks go to Tim and Nicu who were brilliant. I have no hesitation in recommending Core or using them again in the future.

We used Core Sash Window on 3 separate occasions for a total of 8 windows and we are very satisfied with the end result. Communication was easy and they responded quickly when problems occurred. They do need careful managing.

I used Core to replace 2 windows. The quality of the windows is excellent and the carpenters and painter were hard working and competent. They were all pleasant to have around the house and cleaned up perfectly. The company administration is very efficient. I am already looking to get more windows replaced by Core.

Core sash windows did an amazing job on replacing my bay windows. Everyone in the team were friendly, efficient and easy to contact. They are such good quality windows and the installers and decorators had great attention to detail. Tim even organised for additional paint to be dropped by for touch ups when I mentioned the room was still being renovated. I’ll be getting them to do all the windows in the flat and have recommended them to friends. Thanks Core!

Core Sash Windows were recommended to me when I had to have four attic windows replaced. I was very happy with their work so when I decided to have the rest of the windows in the house replaced I asked them to come back. They built and fitted an additional thirteen sash windows and two casements. They were thorough, friendly and helpful throughout. The windows are beautiful, work perfectly and were extremely well finished. The fitters were a pleasure to have in the house and they left everything in excellent condition. I have no hesitation in recommending them.

Core Sash windows replaced the sashes in my front-room bay of four windows. I was very pleased with their services. Sean and the team were helpful and realistic throughout, and communication was good as the work progressed. They stuck to their proposed timetable, the team were very careful with the property, protected the rest of the room they were working in and cleaned away each evening. The workmanship was excellent, from the carpentry to the painting. Cost wise they were in line with other quotes, but I'd have no hesitation in recommending them given the quality product and the overall service.

Having used Core Sash once previously, following much research, for new french doors we didn’t hesitate to use them again to replace old upvc windows at the front of the house with original looking sash windows. From start to finish the whole team were utterly professional. The design matched the original Edwardian windows perfectly. The installers were incredible, meticulous, friendly, they took great pride in their work. They left the site spotlessly clean each day. The attention to detail To the workmanship was second to none. The end result is stunning, we will definitely be using them again.

Core Sash Windows replaced several old, single-glazed windows in our house with new, double-glazed windows, both sash and casement. The staff were highly professional and considerate about the need to maintain distance from us in the house in the current circumstances. The work was done on the planned schedule and completed to a high standard. We are very pleased with the new windows, which are similar in appearance to the old ones but now the draught has gone and we also notice the sound-proofing is better than before.

After having a bad experience with a window replacement some years ago, I was delighted when I found Core. From start to finish they were totally professional and helpful & I am very pleased with the windows & door. I will be using them again in the future.

We had all 6 of our Sash windows of various dimensions replaced by Core and we are very happy with them. They all work well and slide up and down like a dream (you don’t need to be a regular gym-goer). Any slight adjustments or easing we required after the work was completed was immediately tended to with no quibbling. Last, but not least, the noise reduction is amazing as is the energy saving. Last winter we used our heating for less than three hours a day and often just an hour in the morning was sufficient to maintain 20-21C. All the windows are made to detailed measurements and all fitted on arrival. We were constricted by Islington Council Conservation requirements and Core were able to work to those detailed restrictions. Core personnel from our initial contact Dalan Rustemoglu (surveyor), through the office staff to the carpenters and painters, were very professional and helpful. We highly recommend them and now at least 10 other friends and neighbours have, on our recommendation and on viewing the windows, purchased Core windows also. No one has any complaints!

The guys at Core Sash Windows provide a really excellent service. We have used them on a couple of occasions now and each time they have gone above and beyond our expectations of the service provided. Their product is top quality and the whole process from start to finish is efficient and streamlined. I highly recommend them!

We had to replace the top sash of one of our windows. After some research and other good reviews I have seen on Which, I decided to go with Core on this. Their sales team is very helpful, answers all of your questions and pays attention to your needs. The new sash production was on time as promised. The job was scheduled and completed on time as promised. They came in and worked so diligently, when they left, there was not even a single dust in the room. And the window was fitted so nicely and is now operating smoothly. Core has done a great job and if I am ever in need of another sash window work, they will be my go to.

We had 6 sash windows and 1 casement installed in Dec 2019. The installation team arrived on time and were respectful both to us and our property. They kept us informed and cleaned up each day to a reasonable standard. The finish on the windows is fantastic: the final hand coating of paint (by Steven) makes all the difference, and not many companies I had quote offered this. I had previously had 2 sash windows installed by another very large company (LSWC, green logo!) and these windows by Core win hands down - both on appearance, smoothness of operation, and the “making good” of surrounding plasterwork etc. A special shoutout to Steven for that. We did have an issue with on one of the 7 windows we had installed - the architrave used was too large compared to the original and as installed was overlapping the rooms cornicing which spoiled the look of the room. There was a bit of back-and-forth with the company on the matter, necessitating some before and after photos to show the original appearance, but afterwards they did agree to return and fit a smaller architrave at their expense. In an ideal world this would have been picked up by them during the survey and adjustments made ahead of time, but credit to Core, they did return and put it right, so no hard feelings from me and they will be my #1 choice for next time given everything else was top-notch. No experience (yet) of having to call on their warranty.

We had new bay and sash windows from Core Sash. All the staff we dealt with were professional and polite. They took care to minimise mess and inconvenience and the finishing off work was excellent. We had to pause work due to a leaky roof and this was accommodated without fuss. The finishing off work breathed new life into our rather worn and old plaster work and ledges.

From initial meeting to survey work, to measurement and logistics, and then installation and cleaning up, Core Sash Windows did a super job. We are delighted with the work, and would have no hesitation in using them again. In fact, we just called to do just that.

This is the second time we have employed Core Sash to replace our windows and again they did not let us down. From start to finish they were polite, professional, punctual and helpful. We are delighted with our windows which are beautifully crafted and work very efficiently. They cleaned up constantly throughout works and made good and painted around the windows beyond where they needed.

Core sash replaced an original timber sash window for us in our nursery. We were on a tight deadline and they managed to turn everything around for us before Christmas. Customer service was great and we were very impressed with the quality of work and professionalism of the fitters especially, much better than a lot of the tradespeople we used for the house. The finish was great. Expensive but worth the money.

The windows look AMAZING and we are very happy. The team we had were brilliant, so tidy and lovely people to have around. Thanks to everyone at Core.

Core supplied and fitted replacement French windows and frame. First impressions, helpfulness and communication were first rate. We would not hesitate to recommend them.

My experience with Core Sash Windows was simply outstanding. I had 5 sash windows refurbished, replacing the sashes with double glaze timber panes but retaining the window boxes. I retained an original feature of the house whilst installing double glazing which is infinitely better than full PVC replacement and cheaper than full timber replacement. The workmanship in the refurbishment of the box was remarkable and the new double glazed sashes are probably the best I have come across. I admit they were not cheap but the quality justifies the expense. The job was completed in May and so good that I decided to replace another 6 windows in the house which is also done to the same high standard. I highly recommend Core Windows.

Despite confidently assuring us that they would make good and leave no trace, their installers didn't clear up after themselves, leaving rubble and dust on the floor for several days at a time, even when they were applying the top coat of paint (which any good painter will tell you is a cardinal sin!) - and leaving their empty drinks cans lying around. They managed to leave scrapes, scratches and dents on walls and woodwork throughout the house, and made such a bad job of touching up / fixing these issues that they had to come back several times and ended up having to repaint several walls in their entirety. On one occasion I turned up to meet their Director at the house and he was hanging out of the window with a hoover, apparently cleaning the gutter. When I came in, I noticed that he had splattered dirty gutter water across half of the walls... cue another few rounds of touch ups... The windows themselves seem pretty good (they are made by a supplier in Estonia I believe) but the final coat of paint was very messy and left drips running down walls, on the skirting boards, radiators etc., so again this was something they had to come back and fix over several visits. Worst of all is that through all of these issues, their customer service was appalling and made the whole process extremely stressful. From not showing up to meetings, to simply being rude and trying to make excuses for things they were clearly at fault for, and now simply ignoring emails.

We had french doors fitted in our Victorian/Edwardian house. Attention to detail was amazing. The doors look like they’ve always been there except much less draughty and rattling! The service we had from Core was very professional. The doors took a while to make but they are so well made it was worth the wait. We were kept informed of progress at every stage and installation was fast and efficient. The guys on site were very professional - incredibly polite and extremely conscientious. All in all it was a very positive experience. Highly recommend them.

We recently had four sash windows replaced by Core Sash Windows. They requested 8-10 weeks to make the windows. As we approached ten weeks, they made no effort to contact us to let us know the windows were delayed. After rescheduling to the 13th week, we received a call at 3pm the Friday before they were due to start on Monday to say they didn't have one window and had no idea when they would have it. Once they started the work, they got three days in and then didn't show up for two days. They refused to answer the phone and never provided a credible plan for completing the job. Once complete (finally), they chased us for payment within 24 hours and continued to chase every day with multiple calls and email over the next few days. They are awful to deal with and I wouldn't recommend them to anyone.

I recently had 7 one-over-one, top and bottom opening, engineered box sash windows fitted by Core Windows. The original site measuring and ordering process was very smooth with detailed breakdown of each window (materials, window furniture, glass, openings mechanism, cills painting and undercoat systems) which was provided a couple of days after the first visit. I opted for a basic fit as I had builders onsite renovating, and this was carried out to a very highly standard. The windows look amazing and are very solid, with decent weight, smooth opening and cut out a lot of external noise. I’ve already had two neighbours enquire where they are from and whether I’d recommend - in answer to that, I would highly recommend Sean, Tim and the team at Core and would not hesitate to use them again should I need to.

Core made and installed 3 sets of French doors for our Edwardian house. We took ages to decide on a supplier as so many door manufacturers only provide off the shelf products which look cheap and insubstantial. We chose Core because they were prepared to make bespoke doors to our specification at a competitive price. We are delighted with the doors now they're installed. They are beautifully made and finished and the design is completely sympathetic to the age of the house. We had dreaded the fitting process, expecting lots of mess and damage to existing decoration (old doors had to be taken out and new frames installed along with new architrave and skirting). We couldn't have been more wrong - the carpenter and painter were incredibly clean and tidy, clearing up any mess before they left each evening. They were professional, friendly and polite and a real credit to the team. The finish is exceptional - they really went the extra mile to make sure everything was perfect and we were happy. There is no need for any further decorating work - they made good all damage to plaster and trim - you really would not be able to tell that the doors are new. We were so happy with the whole experience. In fact it was so incredibly easy and painless we're thinking of replacing the windows now... Thoroughly recommend them.

We were really happy with the service provided throughout. The survey and install team were friendly and polite and everything has been finished to a very good standard. We wouldn’t hesitate to recommend Core Sash to our friends.

I had a new front door made and fitted by Core Sash Windows in June and am very happy with the end product. I'd originally asked them to quote for sash windows over a year ago, so had dealt with some of the staff at that time. Learning from that experience it was important to me to contract a local company this time. I found them professional and helpful to deal with, from the back office all the way through to the workmen installing the end product. The door itself is a quality product which, in my opinion, is good value when I compare it against some other quotes I received. The only area I could pick out for improvement is communication. I found myself calling up or emailing, asking for updates on a few occasions as the lead time was around 12 weeks and installation would likely have been during working time, requiring some planning on my part. Nevertheless customer service gets 4/5, the only area that wasn't 5/5. Happy to recommend Core Sash Windows given my experience.

We had the large sash windows on our 2nd floor flat replaced in a conservation area. The windows are absolutely stunning and have transformed the rooms and the level of finish both outside and inside was excellent. I had not realised how much work and what a detailed task the finishing would be to make it good as new. One of the window sills had to be adapted on site around a unit that we had purchased that was bigger than expected, this was done free of charge and very neatly. The rooms are draft free and the windows just slide open so smoothly, I wish I had them replaced before. Every member of the team was helpful and pleasant and responded to questions immediately and Core managed to flex delivery to coincide with other building work. The installers were excellent and carried the huge front window up 2 flights of quite a narrow staircase with no problems - I absolutely would recommend - worth every penny!

We were having major house renovation works and started off with the windows. All the windows except the sitting room were renewed. The sitting room has the old, interior, wooden shutters and couldn't be replaced with the double glazed units if those were still to work, so these windows were successfully renovated. It was a very happy relationship with Core from start to finish and three years later we are still completely satisfied and happy. The house is warmer and, above all, much quieter. The new sash windows work beautifully. We strongly recommend them.

We have had a terrible experience with Core Sash Windows: they haven't been able to meet the schedule we agreed when placing the order, after weeks we still haven't received the windows we ordered and they keep installing parts that are just temporary solutions. On top of this, no clear communication whatsoever and we are still struggling to get answers and solutions. We strongly advise against using them!

The Core Sash Windows team supplied and fitted two bay windows to our victorian house. Plus casement windows to our loft extension. Last year we had quotes for PVC sash windows and decided wood would be preferable. Core Sash Windows quote was very competitive in comparison. All members of the team were very professional. The fitters and decorators made every effort to minimise disruption to our household. Covering every piece of furniture during the works and thoroughly cleaning up before leaving each day. Everything was sound and secure at the end of each day. We're very happy with the quality and value of the finished product and are very happy to recommend Core Sash windows.

Great job on installing windows and door - very efficient all round & making the new kitchen/bathroom look really light, the existing repaired ones feel a lot better insulated too.

Good standard of workmanship and truly effective and attractive product. My windows were big & draughty, now they are light & stylish and I'm cosy and warm!

The workmanship on a not so simple couple of sash windows is remarkable. the quality of the finished and installed product is excellent.

Our windows and door are fantastic, exactly what we wanted. Everybody that we dealt with was excellent -professional, kind and helpful. Core sash windows did a great service and I would definitely recommend them. The quality of the windows and door is really second to none.

The windows look amazing. I didn't realise how bad they were until they were replaced. Seems like excellent quality and the installation was carried out quickly and efficiently

The windows are great, the installation team delivered as agreed, they covered the rooms well to protect from dust and cleaned up after themselves well. The decoration after the windows were installed was of high quality too and it was great to see that there was a team visiting daily during the installation process to check on the work and answer any concerns we had. In particular, Mario was great from when he first came to take final measurements to the end when he made sure our roman blinds were back up properly. We used another company before finding Core Sash Windows and had 1 window and 1 door replaced. Their installation was poor leaving cracks on the outside and they did not restore the inside to the original state. They were also quite a bit more expensive. I'm sorry I didn't find Core Sash Windows earlier, it was such a more pleasant experience. Thank you!

Excellent workmanship, nice windows, courteous workers, cleaned up thoroughly. This was done very recently so I can't comment on longevity but the windows look and feel great. I could have used a more detailed description of the windows: I wasn't told about certain details - e.g would I want 'security' knobs, why I wasn't I getting decorative 'horns' on inside? But on the whole really good service ~Many thanks though for a lovely job.

Very proactive - surveyor turned up on time as did fitter. Extremely tidy job and very effective"

Core replaced 2 small single glazed sash windows in summer 2016, problems arose straight away. Despite 6 attempts to rectify, 10 different people from Core attending, they were unable to resolve to acceptable level. They spent total of 8 days, over a 10 month period working on 2 windows. Some of the issues (too many to list)-initial fitting–left a gap 5 cm wide, 2 mm high, could see straight through to outside. Wood severely splintered in the corner joints, paint on glass, holes in timber, paintwork lumpy, dents in putty. When the second fitter saw the newly fitted windows, they asked me twice if they were the old windows. On another occasion, strips of sealant were left hanging off wood, sashes made screeching noises when opened/closed. Manager did attend once, used his credit card to try & smooth out uneven putty, he admitted putty & paintwork was not good. Within 2 weeks of installation, the putty developed multiple deep cracks, within 2 months it was loose and moved. Core replaced the putty-their attempt was wonky, uneven & lumpy. A few months later, Core returned to paint the putty. Paint started creasing within hours, within days started cracking & flaking off. Their reasoning was that it ‘must have rained and been sunny on the putty’. Paint continues to flake & fall off. Core had the substandard windows made by another company. Core’s manager refused to take responsibility for windows. Ungenerous discount given doesn’t cover distress, upset & major inconvenience caused to me + I will have to pay for new windows.

We recently had timber sash windows installed into our property. We ended up going for the basic fit as we were having a number of other work done to the property. This made installation much cheaper and affordable. In comparison the windows were much cheaper that competitors on the market and this was not reflected in the quality as we still got great windows installed. Highly recommended and great service by Dalan Rustemoglu!!!

Three years ago Core replaced some sashes and refurbished others on the back of our Victorian terrace. We also had replicated French doors and a back door replaced. I had no hesitation in asking Core to return for the front window. The information given was clear and no pressure or exaggerated promises were made. Core is able to offer a variety of options e.g. repair and refurbishment and replacement which is helpful if you value original features. I like the open accounting system and the option of insurance for the initial deposit. Financial arrangements were therefore straightforward and reliable. The team as before were professional, punctual, polite and honest and tidied up each day. The finish is excellent and being able to open and air the house more easily is wonderful. Both Daniel and Sean made sure to check that there were no issues. I am very happy and have recommended the company to a neighbour.

It started well, though there were delays and prices seemed on the high side. The team were competent and largely efficient regarding the windows though left the paper on one set of sash cords. The two doors and managements response were a tale of misleading pricing, leading to initial overcharging and lengthy delays because there was, it appears, a lack of internal communication within Core. The new basement door fitted well, but it took months to get the right colour hinges. The front door was much bigger negative issue. There were months of delays as a complaint to the original contact at Core was seemingly never passed on. The workmanship left paint bubbling, this was repaired but then bubbled up again. I was also, more seriously, but not clearly indicated on the estimate, charged for a full door refurbishment. I challenged this repeatedly and was only acknowledged as correct after repeated emails despite a full invoice requested - the discount for the one sided treatment, especially given the faulty workmanship was not generous and the door still required attention. Most of these issues could have been mitigated by more efficient customer service and better internal communications at Core and a better attempt at recognising poor customer management and service

I had researched the well known window and door manufacturers, but Core easily came out tops as they offered the most comprehensive service. The price is also reasonable given the outstanding care and workmanship. Ryan and Marco were full of tips and not pushy as this company has no need to be. Core produced a new front door for my Victorian terrace with a style in keeping with the era, though I chose a colour with a modern edge which compliments the front of my house brightening the exterior and interior. There are a large range of colours to choose from so you can create a bespoke look. The additional warmth created by the insulated door was immediately noticeable. And now I've commissioned core to replace all the sash windows in my home which will be natural wood inside (for a cottage like effect) and white on the exterior. I don't think other companies can offer that level of individual service.

We have been extremely impressed by the level of service and workmanship provided by Core. From the professionalism of the survey to the skill of the workmen involved with the installation and painting of the windows, it was been a flawless process. It may be a bit more expensive than other companies, but it is money well spent with quality that is second to none.

Professional, friendly service and excellent workmanship. Reasonably priced, not the cheapest but reliable, clean and trustworthy. Head carpenter Ryan is responsive, helpful and a very nice chap. I wouldn't hesitate to recommend them.

I was so nervous about appointing someone to do our windows given some of the horror stories you here. However, I couldn't have been happier with Core. They are excellent quality windows, the builders always arrived on time and cleaned up after themselves. The communication and service with their office was always spot on. Payments were easy to keep track of and make through their customer site. And it makes the house so much warmer too - such a noticeable difference. Very happy to recommend to all.

excellent workmanship, amazing cleanliness and finishing off that goes beyond expectation - and great windows!

Excellent service and workmanship. Everyone we have dealt with have been fantastic, especially the fitters whom we're friendly, passionate and extremely diligent. I heavily researched the market and found that Core were the only company to offer a comprehensive service. In that they were willing to undertake the minor building work (repointing and plastering), as well as redecorating that results from the replacement of the windows.

Ours is a typical London Victorian terraced house. After much research and a recommendation from neighbours, we chose Core to replace the windows in our lounge and three bedrooms, and draft proof and re-glaze the front door. From the outset (the initial contact and site survey) it was clear that this was a company that prided itself on a first class product (their website is also very comprehensive) and the quality of its workmanship. The quote was competitive and a start date was agreed. It was to take ten days. At the end of the first week I emailed Core's management and included the following.... Just to say how impressed we are by your team - skilled, diligent, respectful, hardworking, conscientious, cheerful... The superlatives were fully justified and, as the work progressed, it was obvious that the box of each window was being completely refurbished and, with the new windows installed, they would have been fully restored. Neighbours began to notice and ask after the process. On completion, we were assured that 'if any problems arise...' they would be remedied and we were provided with a written guarantee. Put simply, the investment was very worthwhile, the quality of finish was of the highest standard and I can recommend Core to you without hesitation.