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Trusted Traders

Core Sash Windows

Logo on white
Opening Hours
Today - 08:30–17:30
  • Monday 08:30–17:30
  • Tuesday 08:30–17:30
  • Wednesday 08:30–17:30
  • Thursday 08:30–17:30
  • Friday 08:30–17:30
  • Saturday - Closed
  • Sunday - Closed
Profile thumb corelogo


24 Reviews


Core Sash Windows is a London-based double-glazing company specialising in the replacement and repair of traditional timber-framed windows and doors. We understand that replacement windows and doors are an important investment, and you obviously want to make the correct choice.

That is why we offer:

• Elegant and traditionally styled products
• Attentive customer care
• Punctuality and reliability
• Considerate workmanship
• Convenient and fully comprehensive service
• No need for Third Party trades

That is why we promise:

Our surveys are always performed by experienced carpenters instead of designated sales-people - there's no unnecessary up-selling and no high-pressure tactics. Our FENSA-registered installation service also includes the hand painting of your new products, traditional sand-and-cement pointing joints, and the repair of any damaged plaster. And our traditionally designed windows and doors come with a 10 Year Insurance-Backed Guarantee.

What we do

  • Glaziers

    • Sash windows
    • Timber windows
    • Window consultants
    • Replacement window services and repairs
    • Double glazing installation
    • Aluminium Windows
    • Double glazed units
    • Double glazing repair
    • Stained glass
    • UPVC Windows
  • Double glazing

    • Double glazing installation
    • Double glazing suppliers
    • Double glazing repairs
  • Carpenters

    • Joinery and carpentry
  • Doors

    • Bi-fold doors
    • French doors
    • Front door
    • Patio doors
    • Timber doors
    • UPVC doors
    • Orangeries
  • Draughtproofing installers

  • Specialised building trade contractors

  • More Services

    • double glazed timber sash casement windows and doors

Customer reviews

24 reviews
Customer Service
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Beautifully finished windows, draft free windows and a pleasure to deal with
Customer Service
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!
Customer in Greater London28/04/2019
Still warm feelings after three years.
Customer Service
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.
Never use this company!
Customer Service
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 trader replied (on 05/08/2018)
Hi Alessandra, We understand your frustration and we are very sorry that our efforts to expedite the delivery of your new sashes to receive them in 4 weeks (rather than the standard 8 weeks at this time of year) was unsuccessful. Regrettably, despite the factory operating 2 shifts and working 24/7 in this the busiest time of year, the delivery was delayed which put us and you under time pressure. The delays stemmed from the production of the glass units, so I opted to have the finished sash frames delivered un-glazed and had an extra 10 double glazed units manufactured locally. These were fit in the sash frames so you would have natural light and we replaced them when the correct units were delivered. My thinking was that this option would enable us to fit the windows and finish all interior work by your move-in date of 23/07/18. Trying every available option to avoid an impact on you moving in, was, we felt the right choice when the alternative was to start work a week later on Friday 27/07/18 (by which time all windows had been installed). 1 top sash upstairs is waiting for a glazing unit to be swapped and 2 timber corner pieces to be fitted. Everything else was finished on 01/08/18. My communication in the beginning while I was in constant contact with the factory to find solutions, could have been faster while I was waiting for a confirmed (rather than giving you an estimated) delivery date, I hold my hands up that this should have been communicated to you quicker.
Excellent service and product
Customer Service
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.
Michael Anthony19/06/2018
Quick installation & great looking results
Customer Service
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.
The trader replied (on 05/08/2018)
Efficient and stylish double glazed sash windows
Customer Service
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!
Great work
Customer Service
The workmanship on a not so simple couple of sash windows is remarkable. the quality of the finished and installed product is excellent.
Christina Z26/03/2018
Excellent job!
Customer Service
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.
Bea Rob24/02/2018
Very happy
Customer Service
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
Sash window refurbishment and two windows replaced
Customer Service
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!