The Role of Double Glazing in UK Building Regulations

Planning Permission for Double Glazed Window Installation

Before discussing UK Building Regulations for double glazing, it’s important to determine if you’re allowed to build or change a structure in the first place. There are standard guidelines for what falls under permitted development and when you need planning permission for double glazed window installation.

Here are the circumstances when you need or don’t need planning permission:

New Building Regulations for Double Glazing

In addition to planning permission, you also need to comply with the UK Building Regulations, which ensure the quality of installations.

In 2022, the Department of Levelling-Up, Housing, and Communities implemented changes to Approved Documents L and F and introduced a new Approved Document O covering overheating in residential properties. Essentially, these building regulations for double glazing are concerned with energy efficiency, ventilation, and safety.

1. Thermal Efficiency

Building regulations for energy efficiency are intended to reduce your carbon footprint by controlling the amount of heat that escapes from your home. Reducing the amount of heat loss means reducing the energy you use to heat up your house.

Approved Document L has been updated to promote better energy efficiency in new windows, doors, and other glazing products. The new minimum fabric efficiency standards are as follows:

• New windows and roof lights: U-values of 1.4W/m²k or lower (from 1.6W/m²k previously)
• New doors: U-values of 1.4 W/m²k or lower (from 1.8W/m²k previously)
• Fire doors: U-values of 1.8W/m²k (unchanged)

The new Approved Document O was also implemented to resolve overheating problems in residential properties, including new build homes, student accommodation, and care homes. The main principles of these regulations involve reducing solar gain heat by using high quality solar control glazing, limiting the amount of glazing in one room, and adding capacity for shading or other ways to absorb UV rays.

Aside from choosing products that exhibit excellent thermal performance, such as double glazed windows, the government also recommends the use of functional windows that are easy to open for better ventilation.

2. Sufficient Ventilation

Windows ensure sufficient airflow, reducing the amount of moisture inside the house and preventing mould and fungal growth. 

While double glazing’s insulation capacity is one of its main selling points, ventilation is just as important, especially in preventing condensation, which is a common occurrence in double glazed products. Updates in Approved Document F recommend the installation of new windows with trickle ventilators and require installers to ensure that any home improvement project they execute does not compromise the property’s ventilation. 

3. Safety

Safety glazing is a protective requirement where the glass used in certain areas needs to be reinforced to prevent serious injuries when it breaks. This is usually done for double glazed windows that are set low or have large glass panels.

Compliance with Building Regulations

Demonstrating compliance with building regulations depends on who will install your double glazed windows.

A. Self-installation

If you decide to go the DIY route, you need to obtain a certificate from the Local Authority to confirm that the installation has received approval under the Building Regulations. You will also need full Local Authority Building Control approval if you are hiring someone who is not registered to install your windows.

The process can be fairly lengthy, depending on your local council. At the most, it can take up to 8 weeks to receive a decision.

B. Registered installer

If you opt to hire a specialist company registered under a Competent Person Scheme, you simply need to obtain a certificate showing that a registered professional installed your double glazed windows. It helps to have this certificate when you sell your home or in other situations where you may need to prove that the installation complies with Building Regulations. 

Competent Person Schemes (CPS)

Competent Person Schemes allow tradespeople to self-certify certain types of building work they do. There are currently two schemes that regulate the installation of windows and ensure they meet the highest standards:

1. Fenestration Self-Assessment Scheme (FENSA)

FENSA is the largest scheme for installers, widely recognized within the construction industry and by the government. Accredited companies can provide homeowners with a FENSA certificate.

Scope: replacement windows and doors

2. Certification and Self-Assessment (CERTASS)

Is a competent person schemes that enable registered installers to issue a CERTASS certificate. While it also covers windows and doors, it has a more holistic approach and extends to other home improvement works.

Scope: replacement windows, doors, roofing, insulation, and electrical work

Standards and Certification Organizations

Aside from the competent person schemes, various organizations also ensure that the quality of windows being installed throughout the UK is up to standards.

1. British Standards Institution (BSI)

Develops and publishes standards that may be used as a guide in building regulations, ensuring the quality and performance of windows and related products.

2. BM TRADA

An independent and accredited certification body that offers certification services to construction and timber products. While not specific to window installation, a BM TRADA certification may cover some aspects of construction quality and product performance.

3. Glass and Glazing Federation (GGF)

The GGF represents companies that manufacture, supply, or install glass or glazing products in the UK and internationally. The federation promotes best practices and sets the highest technical and health standards for glass and glazing works. Together with other industry bodies, the GGF set up FENSA in 2002.

4. British Fenestration Ratings Council (BFRC)

Introduced the Window Energy Rating (WER) system to determine the energy efficiency of a window. A rating is assigned to a unit according to its solar gain (G-value), heat transmission (U-value), and effective air leakage (L-value) readings, with E being the lowest rating and A++ as the highest.

5. Double Glazing & Conservatory Ombudsman Scheme (DGCOS)

A consumer protection organization that ensures consumers are protected when using a DGCOS accredited member. The scheme supports a network of installers who have undergone a strict accreditation process for the products they offer.

When searching for window installers or construction service providers, it might save you considerable time and resources when you choose the ones that are already accredited by the aforementioned schemes and certifying bodies.

Leading Double Glazing Installers in the UK

Some of the top installers in the UK are Everest, Anglian, First Home Improvements, CR Smith, and Evander.

Suppliers ╲ Features
Guarantee	10 years	10 years	12 years	10 years	5 years (timber); 10 years (UPVC and aluminium)
Finance	9.9% annual percentage rate (APR); 36-180 months	12.9% APR; 36 month	Varies by lender; 0% options available	3.9% APR with 2-5 year term or 0% APR with 4-year term	Not specified
Materials	Timber, aluminium, UPVC	Timber, aluminium, UPVC	UPVC	UPVC with timber sills	Timber, aluminium, UPVC
Affordability (price range per window)	£500 – £1,230	£250 – £1,000	£200 – £750	£250 – £895	Not specified
Accreditations	BSI, FENSA, GGF, BFRC	BSI, FENSA, GGF, BFRC	FENSA, GGF, BFRC	BSI, BFRC	FENSA, GGF
Trust Pilot Rating	4.4/5	3.9/5	4.5/5	4.8/5	4.6/5

Final Thoughts

Installing double glazing marks the beginning of a strategic move towards increasing your property’s energy savings while also contributing to sustainability. Whether you opt for self-installation or hiring registered installers, it pays to understand the nuances of planning permissions and building regulations. Compliance will not only help you avoid legal issues, but will also give you peace of mind and ensure the maximization of your investment.