Most listed Buildings are prohibited from changing their period windows as making alterations would change the aesthetics of the building, local authorities classify this as changing the original fabric of the property. Those unable to change or upgrade their period windows are left with a significant problem, period windows with single glazing can allow vital heat to escape and provides very little acoustic insulation.
Secondary Glazing is an effective solution to enhance period windows and offers many benefits that include increasing the levels of thermal insulation and preventing noise from entering the property. It acts as a second barrier protecting the listed property from the outside elements and helps to protect the property against forced entry.
In most cases, the installation of bespoke aluminium Secondary Glazing is an option for period buildings, it isn’t considered as altering or changing the original fabric of the building. Historic England recommends the addition of Secondary Glazing as they note:
Secondary Glazing when carefully designed and installed allows the original windows to be retained unaltered, and where necessary repaired, whilst reducing air leakage and conducted heat losses. As a result, there is no loss of historic fabric and in most cases, the installation is easily reversible
Modern double Secondary Glazing is manufactured from durable aluminium and can be powder coated in over 200 RAL colours. It is available in a wide range of styles and allows you to match the style and function of your primary window. This will ensure that the secondary glazing is discreet, unobtrusive and barely visible from the exterior of the building.
Secondary Glazing is often installed to increase thermal insulation or to prevent noise from entering the property. Different glass combinations and installation methods can be utilised to offer enhanced acoustic or thermal performance.
The installation will aid with both acoustic and thermal insulation however, for optimised performance, we would recommend a tailored solution to combat your main issue.
The questions to ask are:
Once we understand the purpose of the installation, we can recommend an advanced solution to enhance your windows performance. It is important to note that how the secondary glazing is installed will effect either the acoustic or thermal performance.
Combatting heat loss is a common request from homeowners and commercial property owners as heat loss will substantially increase heating and energy costs. For optimum thermal insulation, we recommend that the Secondary Glazing system is installed as close to the primary window as possible (up to 50mm glass to glass). In addition to the 50mm air cavity, we would recommend specifying 4mm toughened Low-E glass, this glass has a microscopic coating that is designed to reflect heat into the room.
Where noise entering the property is causing a problem, the installation of Secondary Glazing can help, in most cases, it will reduce noise levels by up to 80%. In order to achieve this, the glass to glass air cavity plays a vital role where we recommend introducing a cavity of 150mm to 200mm.
We offer a wide range of different glass types which are designed to have a significant impact upon noise reduction. If the Secondary Glazing can’t be installed with the required air cavity, we can upgrade the glass thickness to provide optimum performance.
We find that in most cases, 6.8mm acoustic laminated glass will cure most noise problems. This type of glass is manufactured with a PVB (polyvinyl butyral) interlayer and is particularly effective at reducing noise from close by vehicles.
Secondary Glazing can be manufactured in a variety of ways and with different glass types, upon surveying, we would always recommend a solution that is designed specifically for your property while achieving exceptional performance levels.
The key to making Secondary Glazing discreet and unobtrusive is to match the style of windows you already have.
For traditional box sash windows, we would advise the installation of Balanced Vertical Sliders. This Secondary Glazed system is manufactured to match the size of your primary window, they operate and function as traditional box sash windows where both panels can open. For enhanced security and to help prevent forced entry, the windows can be locked from the inside. Both panels are supported by spiral balances which allow you to open the window, once the panels are open the spiral balances will hold the panel in place at any given position.
Balanced Vertical Sliders are available in two variations:
This Secondary Glazed system consists of an outer frame and one pane of glass, the glazed panel operates on a hinge and opens into the room. Hinged Units are growing in popularity as the one pane of glass offers minimal effect on sightlines, for enhanced thermal insulation they are available with a double-glazed unit.
Horizontal sliders slide on durable brass rollers and are available with a combination of two to five panels. Each individual panel can be lifted out of the frame giving total access to the primary window, this allows you to clean the back of the glass.
When making changes to your listed property, we would always recommend that you speak with your local conservation officer. They will be able to advise what changes you can make without applying for planning permission.
We specialise in the design and installation of bespoke aluminium Secondary Glazing. Working closely with the UK’s largest and trusted manufacturer, we can provide solutions for the most challenging acoustic and thermal problems.
Secondary Glazing provides exceptional performance however, it is vital that the correct system and glass configuration is specified, this is where our knowledge and experience can help. We can provide recent case studies showing the installation and what benefits were given. Alongside this, we can provide detailed drawings of the proposed solution where you will be able to share these with your local authority. Upon surveying your period windows, we will discuss which Secondary Glazing solution is most suitable and will provide optimum performance levels.