What is secondary glazing?

Secondary glazing is a second custom-made window, attached to the inside of your existing window, creating a double glazed effect, with out damaging or changing your existing windows. Clearview secondary glazing is designed to be discreet and compliment your existing window, decor style and property type.

What is Clearview secondary glazing made from?

The units are manufactured from a combination of a slim seasoned timber perimeter sub-frame and extruded powder coated aluminium profiles, these contain the glass sections, to which numerous options are available. The standard glass is 4mm toughened other glass options are available on request.. All materials are from managed, sustainable abundant sources.

Do you offer different sorts of glass?

Yes, we can provide most glass types, based on the specific needs of your project.

The standard glass is 4mm toughened (we do not offer float/annealed glass) Subject to panel size this may default to 6mm toughened. Laminated, Acoustic, Thermal Low-E, and Obscure glass options can be accommodated.

  • The Classic Range can accommodate up to a 6.8mm glass
  • The Forte range can accommodate up to a 8.8mm glass.
  • The Forte Hinge System can accommodate up to a 28mm Sealed double glazed unit.


How much noise will it cut out?

It is difficult to give exact details, as every property and everybody can be effected differently by noise pollution, however the science confirms, Clearview Secondary Glazing can reduce noise by as much as 80% or by over 50 decibels, (a reduction of 3dB is equivalent to halving the noise energy) this is 5 times greater than either double or triple glazing. This is subject to final specification and installation limitations, these details can be clarified during a consultation with one of our advisors.

How much warmer will it make my property?

We have test certification which confirms that Clearview Secondary Glazing can enhance the thermal insulation of a single glazed window by as much as 65% or a U-Value of 1.868 W/m2K (a U-Value is the formula for measuring heat loss the bigger the number the more inefficient the window is, a standard single glazed window has a recognized U-Value of approx. 5.8 W/m2K. This performance is better than a Class C, with some products  this performance can be as much as A+. English Heritage and Historic Scotland carried out research through Glasgow University which showed secondary glazing out performed  double glazed replacement windows. This is subject to final specification and installation limitations these, details can be clarified during a consultation with one of our advisers.

Will it stop my Condensation?

Clearview Secondary Glazing has a proven track record to eliminate or significantly reduce condensation problems to a point where it is no longer a concern. The naturally occurring problem of condensation varies from window to window and property to property and whilst we can’t guarantee a total cure, the fitting of the Secondary Glazing creates a manageable chamber, reducing most of the problem and, where moisture absorption products can be placed, which are then 10 time more effective. 

What does Secondary Glazing look like?

Pictures show it best, please visit the Gallery

How do I open or clean my windows?

Virtually all Clearview Secondary Glazing is easy access, and we always recommend considering how to best mange your windows should you install secondary glazing. The idea of taking units out in the summer and replacing in the winter rarely effective and generally causes frustration. Our systems are designed to be in-situ all year round and can simply hinged or slide open for quick and easy access for ventilation or cleaning at any time. Lift-Out semi fixed systems are available and offer a cost-effective solution for seldom accessed windows.

Horizontal Sliders, panels sliding left and right (all panels will slide), the panels can also be lifted out of the frame. Panels can be equally split across the width of the frame or offset to match the existing glass sections if required. With a 2 pane slider, both panels will slide. LH = Left Hand, RH = Right Hand, i.e. If the side you are likely to open most often (from inside looking out). is the Left side. the LH version should be selected, this means the Left Hand panel will slide in front of the Right Hand Panel, the Right sliding behind the left.

With a 3 panel standard slider (SS3) this enables the left and right sides to individually slide  in front of the centre panel, there will always be a pane of glass covering the centre, panels can be lifted out. If access to the centre panel of the primary window is required, a CO3 unit should be selected (Centre Opener). LH or RH versions an LH version means the panel will slide from the Left over the right.

Vertical Sliders, Panels sliding up and down, both panels slide, the standard configuration is the bottom panel will slide up in front of the top panel, this can be switch on request. Panels can be equally split of offset to match the primary window if required. Panels cannot be removed, but on some systems can be tilted out of the frame for easy cleaning. The panels are supported by hidden springs so will be held at a desired open position. The panels will not fully slide to the centre point.

Why should I choose secondary windows?

Secondary windows, or glazing, offer all the benefits to double glazing- improved heat retention, lower heating costs, lower greenhouse emissions, improved noise reduction and improved property security, as well as significantly reducing draughts and condensation. It is a lower cost option to full window replacement, and there if no disposal to landfill, it’s quick and easy to install and generally does not require any post-installation decoration. Most importantly, secondary glazing gives an improved living environment. In addition may existing windows have lasted 100 years or more, with little maintenance can last, for many more, protecting the character, charm  and heritage of a property for future generations to appreciate. They will outlast many replacement options without any disposal to landfill and with the enhanced performance they offer a very environmentally responsible solution.

Our property is Listed – can we install secondary glazing?

Yes. In most cases, secondary glazing meets the requirements of Buildings and Conservation regulations associated with both Grade II & I listed buildings, as it is a completely reversible installation that does not effect the fabric of the building. However, subject to your property listing status, we recommend liaising with your local conservation officer who will be able to give you further advice.

Once I’ve ordered my secondary glazing, how long will delivery take?

Clearview Supply Only standard systems are normally dispatched within 15 days from customer approval this would be for rectangular style units but includes splayed reveals and bays if required. More complex requirements, e.g. arched windows. would take a little longer, details would be confirmed at the time of order.

Installation: (if you are using our installation service), This is subject to location, and the specification of your order, but we endeavor to complete within 4-6 weeks from formal survey.


How much does the delivery cost? Delivery is free to most UK mainland locations and is confirmed on submission of the delivery point postcode. However, we have to charge for delivery to the following postcode areas: Scotland: KY / FK / PA / PH / AB / DD / IV / KW / DG / KA. Cornwall: TR / PL / TQ. Wales: SA / LL / SY. Carlisle: CA. This is a single charge per drop (not per unit), and confirmed on quotation. Charges applicable to 1 to 6 unit £75.00 + Vat, 7 units and above £100.00 + VAT

The delivery is a dedicated service (not a mainstream courier) , shipping only the secondary systems, using a small fleet of Mercedes  Sprinter vans (or equivalent). Delivery dates will be notified shortly after approval, Times and dates cannot be selected or specified.  

Can you deliver overseas? No, we can deliver to any mainland UK port or address, for the customer to arrange their own onward shipping arrangements. In line with the standard delivery statement above.

Can the driver assist with unloading? Standard delivery is to kerbside onlyDrivers are only insured to unload to the threshold of the property, we advise that customers make arrangements to assist and to handle the units thereafter.

Please visit the following page for additional ordering information: https://clearviewsg.co.uk/your-order/  

How long does secondary glazing take to install?

It varies. It’s dictated by the size and complexity of the order. Based on a  window approximately sized 1000mm x 1200mm, installation should take under an hour. On an average order size of 8 windows, installation can be complete within a day, it is relatively simple for anyone with basic DIY skills . Clearview secondary glazing is pre-assembled, pre-glazed and pre-drilled for ease of installation.

Do you offer an installation service?

We do have specialist installation team and can provide a fully comprehensive Survey, Supply and Installation service, this is a highly qualified City & Guilds trained team covering all certification requirements for both domestic and commercial projects.

However, this service is limited by size and location of project, and generally limited to an approximate 50-mile radius of our Sheffield Head Office for most domestic sized property. details are discussed and evaluated via a telephone consultation service.

Commercial work is evaluated on a project by project basis

Site assessment visits are only arranged following a consultation with one of our advisers Contact Us 

Where we are unable to offer an installation option, why not consider our Supply Only service for a DIY approach or using a local tradesman, this is easier than you may think and very cost effective. 

Why do I need to make tolerance deductions when measuring?

Primary windows are rarely square and parallel sided, so you need to ensure the widest part of the secondary unit (including the sub-frame) will fit into the narrowest part of the area it is being fitted. Any gaps around the frame are then covered and sealed with the edging trim supplied with the units. It is particularly important that the units are not too tight, and most problems occur because of this,  whilst some adjustments can be made to the Sub-Frame, if the unit is too tight it won;t fit and cant be used, if squeezed in it can distort and cause operational and performance problems. a small gap around the units ensures maneuverability and position to ensure the perfect fit.

See our measuring guide

The recommended 10mm tolerance deduction is for guidance only as the aperture/reveal distortion will dictate unit size/fit adjustments  and requirements.

Do you provide the fixings with the units?

No, we are unable to determine what fixings and packing requirements may be needed due to the vast range of differing window styles and materials. All  fixing material requirements screws, packers etc are detailed in the installation guide.

We do offer an optional fixing starter kit which will usually get you underway and provide sufficient items to install 2 units, details on application or from the quotation extras list.

Trim: With white units the standard trim supplied is white 28mm wide uPVC, this is easy to work with, matches the colour of the unit and is maintenance free. 

With colour units a 27mm wide timber painted trim is supplied as standard to match the units.  this may  require painting and upkeep at some future point.

The trim supplied is in sufficient lengths to cover the front face only, sealing off gaps between the reveal wall and the frame. Additional trim for back trimming or side covering is available as an optional extra.

The customer must satisfy themselves that the standard trim supplied is sufficient for their needs.

Alternative sizes are available on request.

Do you offer a measuring service for Supply Only?

No, we can only offer this service with our installation option. Following our measuring guidance is easier than you may think. 

Do I need the sub-frame?

We always recommend that the sub-frame is included, this is pre-attached to the system at the point of manufacture. This has several benefits and is hidden by the edging trim on completion. It enables gaps around the frame in out of square apertures to be easily covered and give a better blended and unobtrusive finish. It enables minor adjustment to be made on installation and to notch out around lumps, bumps or cables etc. it also enhances insulation performance with expansion and contraction during seasonal changes.

The sub-frame is a value engineered product, designed to be hidden from view on completion, it is designed to protect the unit in transit and can arrive marked, with nicks scratches and knots, joints in the sub-frame will move in transit. All these aspects are perfectly normal and will not deteriorate the performance or final appearance of the unit when fitted. 

Units can be supplied without the sub-frame, this is a special-order requirement and Clearview need to apply this on behalf of the client. It does not alter the price, but measuring becomes far more critical as onsite adjustments can’t be made and gap filling around the unit must be considered. See our Installation Guide

What is Face & Reveal Fixing?

Face Fixing is where the Secondary Glazing unit is attached directly on to the face of the primary window frame, screw fixing through the front to the back of the secondary glazing.

Reveal Fixing is where the unit is attached to the side walls of the window reveal (the reveal is the depth of the window sill area) the screw fixings going in side to side / up and down. This is usually required if, (a) there is not enough frame on the primary window available to attach the unit to or (b) you want to increase the air-gap between the primary glass and the secondary glass to increase the sound-proofing performance.

See Face & Reveal Fixing

How does secondary glazing installation affect the existing window?

Other than drilling several small fixing holes into the existing window frame or surround, your primary window remains untouched and fully intact when you install Clearview secondary glazing. You will still be able to access your primary window all year and in most cases with a hassle free sliding or hinging option instant opening for ventilation cleaning and maintenance is assured.

Can secondary glazing be made to fit our unusually shaped window?

Yes. In most cases Clearview can provide glazing units to fit most existing profiles, even complete circular designs, alternatively we can design a bespoke solution. if you send us some images we can offer advice, but in most arched cases we require a template for manufacturing.

Skylight or Velux style windows, we also advise caution if trying to secondary glaze a window with a sloping or roof setting. it is critical to consider the safety and securing of both the frame and any moving/removable panels. Most sliding options do not perform well. WE would advise a lift-out unit is probably best suited fitted with a locking bolt to secure the panel.

What colours are the secondary glazing frames available in?

Clearview frames are available in a wide range of colour options. Clearview Secondary Glazing systems are supplied in White as standard. However, there are a number of stock colour options, Off-White, Cream, Dark Brown, Grey & Black, these carry an additional charge over the standard finish.  200 Bespoke colour options are also available, price on application.

Will I need to redecorate after my secondary glazing is installed?

No – in most cases, unless your room is already undergoing decoration, the installation of Clearview Secondary Glazing does not require your room or area to be cleared or covered, other than allowing access to the window area. Your room will be left in a comparable condition to before the installation.

How much does Secondary Glazing cost?

Clearview secondary glazing is a bespoke product tailor made to the customer’s specific needs, each unit is built to meet the most effective solution for Appearance, Performance, Practicality and Price. As there are many options available so there isn’t a simple off the shelf price. As specialists in this field our consultation service is a great place to start. However, our online Supply Only Fastquote service can give you an instant price and is customisable to get your perfect design. For installation services please contact us

My question isn’t answered here, what can I do?

Email us details of your query, and we’ll be back to you asap.

GET A FREE QUOTE CALL 0114 294 5018
Get a QuoteContact UsShare on TwitterShare on Facebook