Single glazing
The term 'glazing' refers to the glass component of a building's facade or internal surfaces.
Historically, the external windows of buildings were generally single glazed, consisting of just one layer of glass, however, multi-layered glazing system were developed such as double glazing and triple glazing to improve performance.
Single glazing comprises off one layer of glass, bedded into the window frame. Single glazing is traditionally fixed with linseed oil putty and secured with glazing nails into the frame. Glazing beads can further secure the glass and are usually screwed and glued to the frame. If the window frame is timber it must be painted or otherwise treated to avoid water ingress.
Single glazing has poor thermal performance, and may not be permitted in new buildings other than those which do not have controlled internal environments, such as storage facilities.
U-values (sometimes referred to as heat transfer coefficients or thermal transmittances) are used to measure how effective elements of a building’s fabric are as insulators. That is, how effective they are at preventing heat from transmitting between the inside and the outside of a building. Typically, the U-value of single glazing is around 4.8 to 5.8 W/m²K, whilst double glazing is around 1.2 to 3.7 W/m²K. Triple can achieve a U-value of below 1 W/m²K.
Thermal performance is affected by the quality of the installation, the inclusion of thermal breaks in the frame, suitable weather seals, and the type of glass used. For example, low-e glass has a coating added to its surfaces to reduce its emissivity so that it reflects, rather than absorbs, a higher proportion of long-wave infra-red radiation.
The sound reduction achieved by single glazing (6 mm thick) is typically around 27 dB, whilst double glazing (with a 100 mm air space) is around 42 dB.
It should be noted that from 1st April 2020 it will be against Building Regulations to rent a property which breaches the minimum requirement of an E rating on an EPC certificate. Single glazing can have a big impact on the energy efficiency of a building and to comply with the regulations, single glazing might have to be adapted. Secondary glazing can be an option if double glazing can not be installed.
[edit] Related articles on Designing Buildings Wiki
- BFRC window rating scheme.
- BREEAM Visual comfort Daylighting.
- BREEAM Visual comfort View out.
- Daylit space.
- Domestic windows.
- Double glazing.
- Double glazing v triple glazing.
- Glass.
- Glass manifestation.
- Glass mullion system.
- Glazing.
- Low-E glass.
- Patent glazing.
- Rights to light.
- Secondary glazing.
- Stained glass.
- Structural glass assembly.
- Tempered glass.
- Triple glazing.
- Types of window.
- U value.
- Window.
Featured articles and news
How big is the problem and what can we do to mitigate the effects?
Overheating guidance and tools for building designers
A number of cool guides to help with the heat.
The UK's Modern Industrial Strategy: A 10 year plan
Previous consultation criticism, current key elements and general support with some persisting reservations.
Building Safety Regulator reforms
New roles, new staff and a new fast track service pave the way for a single construction regulator.
Architectural Technologist CPDs and Communications
CIAT CPD… and how you can do it!
Cooling centres and cool spaces
Managing extreme heat in cities by directing the public to places for heat stress relief and water sources.
Winter gardens: A brief history and warm variations
Extending the season with glass in different forms and terms.
Restoring Great Yarmouth's Winter Gardens
Transforming one of the least sustainable constructions imaginable.
Construction Skills Mission Board launch sector drive
Newly formed government and industry collaboration set strategy for recruiting an additional 100,000 construction workers a year.
New Architects Code comes into effect in September 2025
ARB Architects Code of Conduct and Practice available with ongoing consultation regarding guidance.
Welsh Skills Body (Medr) launches ambitious plan
The new skills body brings together funding and regulation of tertiary education and research for the devolved nation.
Paul Gandy FCIOB announced as next CIOB President
Former Tilbury Douglas CEO takes helm.
UK Infrastructure: A 10 Year Strategy. In brief with reactions
With the National Infrastructure and Service Transformation Authority (NISTA).
Ebenezer Howard: inventor of the garden city. Book review.
The Grenfell Tower fire, eight years on
A time to pause and reflect as Dubai tower block fire reported just before anniversary.
Airtightness Topic Guide BSRIA TG 27/2025
Explaining the basics of airtightness, what it is, why it's important, when it's required and how it's carried out.
Construction contract awards hit lowest point of 2025
Plummeting for second consecutive month, intensifying concerns for housing and infrastructure goals.
Understanding Mental Health in the Built Environment 2025
Examining the state of mental health in construction, shedding light on levels of stress, anxiety and depression.