Replacement Windows & Doors in Oxfordshire

We’ve been installing double glazing windows and replacement doors in Oxford and across the county of Oxfordshire including Witney, Abingdon and Bicester since 1997 and pride ourselves on quality products with a high level of service to match.

Based in Bicester, Oxfordshire, we serve customers across a number of local counties, designing and fitting a range of quality windows and doors at competitive prices.

To ensure you get the best service, we’re accredited Fensa members and all of our installations comply with current thermal performance standards as well as coming with a full 10-year guarantee.

With all of these benefits, you can be sure that our products and service standards exceed industry standards.

We’re extremely proud of our excellent customer service track record from a recent independent installation quality survey.

Our Range of Double Glazing Windows & Doors

We have a huge range of windows and doors for your home, whether you’re looking for new sliding patio doors or insulating uPVC double glazing, we have something to suit your home and your needs.

Casement Windows with Georgian bars and white frames in Oxford

Our uPVC windows are available in a stylish range of styles and colours, including trendy pastel options such as Cherwell Green as well as woodgrain finishes.

Sash Windows Oxfordshire

Sash windows are a wonderful choice if you’re looking to add a touch or elegance to your home or ensure your upgrades are in keeping with the rest of your property.

uPVC Timber Windows Oxfordshire

Our uPVC timber windows are becoming increasingly popular, offering the beauty of timber with the energy-efficiency and hardiness of uPVC.

Casement Windows Oxford with Dark Blue Frames

Our casement windows are extremely versatile and are a continuously popular choice for many. Choose from an extensive colour palette and range of styles to suit your home.

Dark-framed French Windows in Oxfordshire

Choose French windows to add a touch of elegance and character to your home and team them up with a pair of brand new French doors for a full exterior home makeover.

Free Quotation Without a Sales Visit

Worried about sales visits in your home – don’t want the hassle of someone trying to sell you something? We have specialist software that can generate an initial quotation for you from the comfort of your own home – all we need is photographs of your home and your choice of colour.

Replacement Doors

We offer a selection of beautiful replacement doors for both the front and back areas of your home. Our range includes Composite doors, uPVC doors, bi-fold doors and French uPVC Doors.

uPVC door installation in Oxfordshire by Isis Windows

Whether you’re looking to replace your front door or are thinking about having a new Bi-folding door fitted to improve your home, we can help.

A Composite Door in Oxfordshire Installed by Isis Windows

Our composite doors are exceptionally secure, energy-efficient and designed to stay looking good on the inside and out, year in and year out.

Bi-fold doors installed on a conservatory in a house in Oxfordshire

Our bi-folding doors come in an array of finishes and colours, including woodgrain effect, with a slim sightline and superb levels of security.

Sliding Doors installed in a house in Oxfordshire by Isis Windows

Our low maintenance, PVC sliding models are easy to close and open and provide your home with an attractive solution and top energy ratings.

Why Choose Isis Windows?


High level of service

We’ve got years of experience and many happy customers across Oxford & Oxfordshire. We pride ourselves on great customer service and great quality products, all with a 10-year minimum guarantee.



We’re FENSA registered and all of our work comes with at least a 10 year guarantee, backed up by GGFi.


Established local company

Providing new Windows and Doors to Oxfordshire since 1997.

We have a wide range of windows and doors to suit your home and budget. Our Double Glazing Windows and Replacement Doors all come with a minimum of 10-years guarantee for your peace of mind

Isis – What’s in a name?

Isis is a name with a long, proud history. Its first recorded use is as Isa in 1350, while the first evidence of its modern form dates from 1577.

It was also the name of an Ancient Egyptian goddess, later worshipped by Greeks and Romans, but, in Oxford, Isis has long referred to the stretch of Thames north of Iffley Lock.

It comes from the old name for the River Thames, Tamesis, which in the Middle Ages was wrongly taken to be a combination of Thame and Isis.

Isis has long been associated with Oxford rowing. Its the name of the famous university’s reserve boat for its rowing crew, and of a student magazine first set up in 1892.

The university’s research and technology company is also called Isis, as are several other businesses and organisations keen to highlight their connections with Oxford.

We love Oxford and Oxfordshire, too, and are delighted to have our pride in our city reflected in our name.

the river Isis in Oxford, Oxfordshire

A FENSA Approved Windows & Doors Installer

FENSA is a government-authorised scheme that monitors building regulation compliance for replacement windows and doors. Every FENSA Approved Installer, from large national brands to small local companies, is assessed regularly by us to ensure its standards are continually maintained.

FENSA have recently just released their first TV advert!