Questions answered
Sash windows, answered straight.
The questions we are actually asked, answered in full rather than teased. Every figure here comes from Victorian Sliders’ own literature or their Declarations of Performance. Where the honest answer is no, it says no.
Where we work, and what that means
The most common thing to get wrong about us. We run two different services with two different coverage areas.
Do you supply sash windows nationwide?
Yes. Supply-only orders are delivered anywhere in Great Britain, kerbside, through the Victorian Sliders depot network. You send a schedule of sizes, the windows are built to it, and they arrive on your site. Fitting is not included in a supply-only order.
Do you install sash windows nationwide?
No. Installation is limited to West London and the Home Counties: Buckinghamshire, Berkshire, Oxfordshire, Surrey, Hampshire, West London and Hertfordshire. Outside those areas we can supply and deliver the windows, but you would arrange your own fitter.
Can I buy sash windows supply only, without installation?
Yes, and it is a large part of what we do. Supply-only suits builders, main contractors, developers, self-builders and competent trades. You get full control of colour, glass, hardware and glazing bar layout, a lead time confirmed in writing before you order, and kerbside delivery. On a supply-only order the sizes are yours, because we have not surveyed the openings.
Who is responsible if a supply-only window does not fit?
On a supply-only order the sizes are yours, because the windows are built to the schedule you provide and nobody from our side has seen the openings. Made-to-measure windows cannot be returned because an opening turned out to be a different size. If you want that risk to sit with us, choose supply and installation, where we survey before anything is ordered.
The windows themselves
Specification questions, answered from the manufacturer's own literature and Declarations of Performance rather than from memory.
Who manufactures the windows?
Victorian Sliders, in Llanelli, Wales. The product is ECOSlide®. Sash Window Factory is a Victorian Sliders partner: we supply the windows and, inside our catchment, install them. We do not manufacture windows ourselves.
How energy efficient are uPVC sliding sash windows?
ECOSlide® carries an A+ Window Energy Rating. Because they are made to measure and colour matched, the frame fills the opening without packers, so there are no gaps to draught through. A weather bar is mechanically joined to the bottom sash, pushing rain off the sill rather than into the frame.
How secure are uPVC sash windows?
ECOSlide® meets PAS 24: 2022 as standard and is also available as a Secured by Design window, which is the police-backed standard and satisfies Approved Document Q where a property is built to it. An anti-lever bar is built into the sash so it cannot be forced open with a crowbar, high-security cam locks hold both sashes top and bottom, jam blocks are fitted to the top of the sash, and travel restrictors are standard. Toughened glass is used on accessible openings.
How do they perform in wind and rain?
Wind resistance is Class C4 at 1600 Pa, tested to BS EN 12211. That is worth knowing on exposed elevations and coastal sites.
What colours can I have?
Any classic RAL shade, sprayed, or matched to a Farrow & Ball colour. The inside and the outside do not have to be the same colour. Shaped frames and custom glass are also available.
What hardware finishes are available?
Eight finishes, including Antique Gold, covering sash fasteners, lifts and inset finger pulls.
Do the windows tilt in for cleaning?
Yes. Both sashes tilt inward, so upstairs windows can be cleaned from inside the room without a ladder.
What guarantee comes with them?
A 10 year warranty. Warranty certificates are issued by the manufacturer against the job number. Where we have installed, our workmanship is covered in addition, backed by an insurance-backed guarantee through the Consumer Protection Association.
Period property and conservation areas
Most of our installation catchment is Victorian and Edwardian, and a good part of it is inside a conservation area.
Will uPVC sash windows suit a period property?
The thing that decides it is the glazing bar layout and the sightlines, not the material. Panes divided the way the originals were, sightlines that are not suddenly much fatter, and a colour that suits the street will read correctly from the pavement. Georgian bar layouts and any RAL or Farrow & Ball colour cover almost every case we meet.
Do I need permission to replace sash windows in a conservation area?
It depends on the property and the local authority, and it is worth asking them before you order. Conservation area status does not automatically prevent replacement, but a planning officer will usually want the original proportions kept. Tell us at survey if the property is listed or in a conservation area and we will specify accordingly. We cannot give planning advice and we would not want you to rely on us for it.
Do replacement windows need to meet Building Regulations?
Yes. Replacement windows are notifiable work. Where we install, the job is registered under a FENSA certificate issued to you on completion, which is the document a buyer's solicitor asks for when you sell. On a supply-only order, notification is the responsibility of whoever installs them.
Trade, specification and technical
For builders, developers, architects and specifiers.
Are Declarations of Performance available?
Yes, and they are downloadable from the homepage without a form. BS EN 14351 for windows, BS EN 1279 for sealed units and BS EN 12150 for toughened glass, all dated 28 November 2025. The manufacturer also holds ISO 9001 and ISO 45001.
How does delivery work on a trade order?
Kerbside drop through the manufacturer's depot network. Someone needs to be on site to receive, check and sign for the load. Inspect the goods and note any visible damage on the delivery paperwork before you book scaffolding or other trades. Damage should be reported within 48 hours.
How far ahead do I need to order?
Lead times are confirmed in writing before you commit, against your specific order. We do not publish a standard lead time, because it moves with the specification and the time of year, and a number that is wrong is worse than no number.
Can you price a whole development?
Yes. Send one schedule covering every elevation and we will price it as a whole, including phased delivery to site. Developments can be supply only or supplied and fitted, depending on where the site is.
Still not answered
Call 0800 861 1450, message us on WhatsApp, or email info@sashwindowfactory.co.uk. If it is a specification question, the brochures and Declarations of Performance are on the homepage, ungated.