Technical Information

Acoustic Laminate Glass

Laminated Glass with an Acoustic PVB interlayer provides noticeable insulation against noise and helps create quieter interiors. Manufactured by Saint-Gobain it has a totally transparent interlayer which absorbs sounds and significantly reduces the level transmitted through the glass. It helps to keep invasive noise levels out, or to keep noise in.




Traditional Glass patterns

Modern obscure glass patterns are usually unsuited to period and heritage property. We offer a range of glass types to provide a visual barrier or total visual block. These include simple ‘sandblasted’ or ‘satin’ effect for maximum privacy or ‘etch’ type glasses produced using a process originally patented by John Davenport in 1806. This process uses ground glass fired onto the surface of the glass at high temperature to form an integral part of it and create a ‘frosted’ appearance. They are available in a range of traditional patterns which diffuse light whilst providing a visual barrier.


See pattern examples here


Low emissivity – (Low E) Glass

The Building Regulations now require all replacement windows & doors to meet stringent insulation standards (unless they exempted as ‘Historical Buildings’ – see below).


This standard can only be achieved by including a sheet of ‘low E’ glass in the sealed unit and this works by reflecting heat back into the room thereby reducing energy consumption. It is 3 times more efficient than standard glass. The product can be used on either the inner or outer pane, may be toughened for safety purposes and used in combination with any other glass, such as Acoustic Laminate or privacy.

The Building Regulations & ‘Historic Building’ Exemption

The Building Regulations 2000: L1B – Conservation of Fuel & Power in existing dwellings (as amended on 6th April 2006 & 2010) sets out the requirements for compliance when replacing existing windows and doors in residential property.


The requirement in simple terms is to save energy, and the document provides details on acceptable self-certification schemes for replacement works such as CERTASS Accreditation.


Compliance is normally required when fully replacing a window or door, this needs to include the surrounding Box or Master Frame, but is not required for overhauls, upgrades or part-renewal.


In addition, properties classed as ‘Historic Buildings’ are specifically exempted and the regulations do not apply. This applies to all buildings which are:


i) Listed in accordance with section 1 of the Planning Act 1990


ii) In a Conservation area designated in accordance with section 69 of that Act


iii) Where compliance would unacceptably alter the character or appearance of the property


The L1B Approved Document is available here:


The exempt dwellings section is detailed on Pages 7 & 8.

Acoustic Glass London
London Sash Window Company
1432a Clock Tower Rd, Isleworth London TW7 6DT

“We’ve recently had 12 large sash windows fully refurbished and have been extremely impressed by the quality of the workmanship, attention to detail and customer service.”

Mr C Smith, London

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