Best Secondary Glazing Companies in the UK: How to Compare Selectaglaze and the Alternatives

If you have started researching secondary glazing, you have probably come across Selectaglaze. It is one of the best-known names in the UK market: a long-established manufacturer that supplies its systems through a network of approved installers and has worked on many well-known heritage buildings.

It is a strong option. It is not the only one. This guide explains the different types of secondary glazing companies in the UK, what each is good at, and how to compare quotes fairly, whoever you choose.

We are a London secondary glazing specialist, so we are not neutral. We have tried to keep this guide factual and fair, and we encourage you to get more than one quote.

The Four Types of Secondary Glazing Supplier

1. National manufacturers with installer networks

Selectaglaze is the best-known example. The manufacturer designs and makes the frames, and approved installers survey and fit them. You get a recognised product range, published test data and consistent quality.

• Strengths: Proven systems, published acoustic and thermal test results, wide range of opening styles, strong heritage track record.
• Consider: Prices often sit at the premium end, and your experience still depends on the local installer.

2. Specialist local installers

Independent firms that survey, specify and fit, sometimes using their own frames and sometimes using a manufacturer's system. This is the category we belong to.

• Strengths: Direct contact with the people doing the work, local knowledge of conservation officers and housing types, and often more flexibility on design and price.
• Consider: Quality varies widely, so check references, guarantees and the exact glass specification.

3. General window and double glazing companies

Some replacement window companies also offer secondary glazing as a side line.

• Strengths: Convenient if you are also replacing other windows.
• Consider: Secondary glazing is a different skill. Ask how many installations they do each year and whether they understand acoustic air gaps and listed buildings.

4. DIY kits

Magnetic and clip-on kits you measure and fit yourself.

• Strengths: Lowest cost, removable, good for renters.
• Consider: Thinner glass or acrylic, limited noise reduction, and usually fixed or lift-out only. See magnetic secondary glazing and DIY vs professional installation.

How to Compare Quotes Fairly

The cheapest quote is often cheaper because it specifies less. Ask every company the same questions so you are comparing like with like:

1. What glass, exactly? 4mm float, 6.4mm laminate, 10.8mm acoustic laminate? Low-emissivity coating or not? Read our glass thickness guide.
2. What air gap? For noise, 100mm or more makes a big difference. See our air gap guide.
3. What opening style? Vertical slider, horizontal slider, hinged, lift-out or fixed? See our types of secondary glazing.
4. Is the survey done in person? Bespoke frames need accurate measuring.
5. What guarantee, and is it insurance-backed?
6. Who fits it? Directly employed fitters or subcontractors?
7. Is there published test data? Ask for sound reduction (Rw dB) and U-value figures for the system offered.
8. Heritage experience? If your home is listed or in a conservation area, ask for examples near you.
9. What is included? Making good, removal of waste, finishing colours, locks and child restrictors.

Red Flags

• A price given over the phone without a survey.
• No stated glass thickness or air gap on the quote.
• Pressure to sign on the day for a discount.
• Claims of a specific noise reduction without knowing your noise source.
• No written guarantee.

Prices

Prices vary by supplier type, window size and specification. For current London figures, see our secondary glazing cost guide.

If You Are in London

We survey, design and fit across all London boroughs. See our secondary glazing London page for how we work, or book a free survey and compare our quote with anyone else's.

Frequently Asked Questions

Who is the best secondary glazing company in the UK?

There is no single best company for every home. National manufacturers such as Selectaglaze offer proven systems; good local specialists can offer more direct service and flexibility. Compare on glass specification, air gap, guarantee and references.

Are there alternatives to Selectaglaze?

Yes. Independent secondary glazing specialists, other manufacturers and DIY kits are all alternatives. Get two or three quotes and compare the exact specification.

What should a secondary glazing quote include?

The glass type and thickness, air gap, opening style, frame finish, guarantee, and whether making good and waste removal are included.