# Core Sash Windows Core Sash Windows is a carpenter / joiner in London. Rated 4.6/5 from 63 public reviews across 2 named sources. This is the MyTrustedTraders public-evidence profile — independent reviews, credentials and registry data cross-checked across named sources, with no ads and no paid placement. ## About 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. ## Public review evidence (by source) | Source | Average rating | Reviews | | --- | --- | --- | | Which? Trusted Traders | 5.0/5 | 63 | _Per-source review counts are per platform and may overlap — they need not sum to the 63 cross-checked total above._ ## In customers' own words _Verbatim quotes from this trader's public reviews, each attributed to its source:_ > "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." > — Customer in Greater London (5.0, via Which? Trusted Traders) > "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." > — Customer in Greater London (5.0, via Which? Trusted Traders) > "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." > — Customer in Greater London (5.0, via Which? Trusted Traders) ## Trades Carpenter ## Independent verification _What MyTrustedTraders independently checked for this business (verified items only):_ - Review volume: MTT is showing 63 public reviews on this profile. (via Companies House) - Source profile spread: MTT is showing 3 source profiles for this trader. (via Companies House) - Business identity: MTT is showing public business identity data with operating status unknown. (via MyTrustedTraders public listing) - Contact phone: MTT is showing a public phone contact on this profile. (via MyTrustedTraders public listing) - Website: MTT is showing a public website for this trader. (via MyTrustedTraders public listing) - Accreditations shown: MTT is showing 1 credential or accreditation on this profile. (via Public credential evidence) Full verification checklist: https://mytrustedtraders.com/traders/core-sash-windows/checks ## Credentials & sources - Verified credentials on file: 1 - FENSA - Companies House status: unknown - Evidence held from: Companies House, Which? Trusted Traders - Public evidence last checked May 2026 ## Contact - Phone: 02033022060 - Website: http://www.coresashwindows.co.uk/ --- Source: MyTrustedTraders — https://mytrustedtraders.com/traders/core-sash-windows Real public evidence only: every figure traces to a named source and is cross-checked. If a source does not carry a field, it is not shown.