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About Process

We know how important it is for you to understand how we work. At Core Sash Windows, we strive to make this purchasing process as clear and as stress-free as we can, so that you can be content in the knowledge that you’ll be getting the product and service that is right for you. We will also provide you with a 10 year guarantee for your peace of mind. Below, we have mapped out the key parts of our process.


STEP 1: Use The Estimate Tool
After getting an estimate, we will call you back within 48 hours to better understand your wooden window and door requirements.

STEP 2: Arrange a Survey
We will visit you to carry out a free, no obligation survey, Monday – Friday, 7am – 12 midday.

STEP 3: Receive your Estimate
We will email you a link to your online estimate within 48 hours of your survey. This online estimate will outline all of your requested options at our best possible prices.

STEP 4: Accept the Estimate
We will send over your invoice and a GGFI-backed Deposit Insurance Form for your peace of mind. A different surveyor will then visit you to take a second set of measurements before your order is placed.

STEP 5: Relax
Wait 8 – 10 weeks for your products to be manufactured and delivered to our London storage.

STEP 6: We Work
Our working hours are Monday – Friday, 8am – 5pm, and Saturday, 8am – 1pm.
We require parking permits for 2 vans for the duration of the works.

STEP 7: Enjoy
We issue you with a FENSA Certificate (where applicable) and our 10 Year insurance-backed guarantee. Now all you have to do is enjoy being warm and comfortable!