How to start a window fitting business in the UK

Is window fitting a good trade to get into?

Window fitting occupies a unique position within the UK building trades. It benefits from consistent demand due to several factors. Firstly, there's the government's ongoing push to improve home energy efficiency. This has led to an increasing number of homeowners looking to replace old windows with more energy-efficient models. Secondly, many double-glazing units installed during the 1990s and early 2000s are reaching the end of their lifespan, necessitating replacement. Finally, with new-build completions in the UK averaging around 230,000 homes per year, there is a steady stream of opportunities in this sector. Even when economic conditions are less favourable, the necessity of replacing failed sealed units or damaged frames ensures that window fitting remains a viable trade.

The financial aspect is appealing as well. The average window fitter in the UK earns between £28,000 and £45,000 annually when employed. However, running your own business can be even more lucrative. A sole trader with minimal overheads can achieve a turnover ranging from £40,000 to £70,000 with a solid client base. This figure can increase significantly if you expand into areas such as conservatories, bi-fold doors, or commercial projects. The potential for growth is substantial if you are willing to diversify and take on more extensive work.

Qualifications and Certification

While there is no single mandatory licence required to fit windows in the UK, two key areas are of paramount importance for legal and commercial trading:

FENSA or CERTASS Registration

Window and door replacement falls under "controlled work" as per the Building Regulations (Part L for England and Wales). This means it must meet specified thermal performance standards. By becoming a FENSA or CERTASS-registered installer, you can self-certify your work, streamlining the process for both you and your customers. Without this registration, each job necessitates a Building Control application, which can be time-consuming and costly, potentially deterring customers. FENSA registration fees typically range from £200 to £400 annually, depending on your turnover. You can apply at fensa.org.uk. CERTASS offers a similar scheme with comparable costs and benefits.

Glass and Glazing Qualifications

Acquiring an NVQ Level 2 or 3 in Fenestration Installation provides you with recognised credentials and is often a prerequisite for larger contracts. City and Guilds and NOCN both offer relevant qualifications in this field. If you aim to work in sectors such as social housing or commercial contracts, having formal qualifications can significantly enhance your chances of securing work. Additionally, investing in ongoing training can keep you abreast of the latest techniques and regulations, ensuring your skills remain relevant and in demand.

Tools and Equipment

Setting up initially, the essential toolkit for a window fitter includes several key items. These are a cordless combi drill and impact driver, an angle grinder for cutting sill extensions, and an oscillating multi-tool for removing old frames. You’ll also need spirit levels (both 600mm and 1200mm), silicone guns, and a selection of plastic packers in various sizes. Tape measures, squares, and marking tools are also indispensable. To compile a decent set of hand and power tools, budget between £1,500 to £3,000. A reliable van is crucial for transport — most window fitters opt for a medium wheelbase Transit or similar, equipped with good racking to protect frames during transit. Remember, investing in quality tools can save money in the long run by reducing repairs and replacements.

How to Price Window Fitting Jobs

Pricing can vary significantly depending on several factors such as the frame material, job size, and geographical location. To give you some benchmarks for 2026: the cost to supply and fit a standard uPVC casement window ranges from £400 to £700. For a uPVC bay window (3 panes), expect to charge between £1,200 and £2,000. Aluminium casements can be priced between £600 and £1,100. Replacing a front door typically costs £800 to £1,800. For jobs involving only the replacement of failed sealed units, charges usually range from £80 to £180.

When dealing with customer-supplied frames, labour-only rates typically range from £80 to £150 per window, depending on the complexity of the installation. It's beneficial to use a tool like a quote generator to produce professional quotes for customers. This not only helps in maintaining transparency but also significantly improves conversion rates, as customers are more likely to trust a clearly laid out and professional presentation of costs.

Insurance for Window Fitters

Insurance is a vital consideration for any window fitting business. At a minimum, you will need public liability insurance with at least £2 million of cover. This generally costs between £200 and £400 annually for a sole trader. If you employ staff or engage labour-only subcontractors, employers' liability insurance is legally required. Additionally, consider tools and equipment insurance to protect your investments and contract works insurance to cover materials and work in progress in case of damage before completion. For more insights on safeguarding your tools, see our guide on tool theft insurance for tradespeople.

Finding Your First Customers

Word of mouth remains the most effective way to secure work as a window fitter, but establishing a solid foundation is essential. Start by setting up a Google Business Profile and encourage every satisfied customer to leave a review. Having as few as five genuine reviews can place you ahead of many competitors. Register on platforms like Checkatrade, TrustATrader, or MyBuilder to receive leads while building your reputation. Despite the digital age, traditional methods like leaflet drops in residential areas can still be effective for local trades. Consider partnering with local estate agents and letting agents for window replacements in rental properties. Additionally, connecting with local builders who require windows fitted on refurbishments can open new avenues for work. For more strategies, visit our guide on winning more quotes as a tradesperson.

Invoicing and VAT for Window Fitters

Understanding VAT is crucial for a window fitting business. You must register for VAT once your taxable turnover exceeds £90,000 in a 12-month period, as per the 2026 threshold. Most window fitting work supplied and fitted to residential customers is standard-rated at 20% VAT. However, some energy-saving work may qualify for a reduced rate. It is important to check the HMRC guidance on VAT for energy-saving materials to ensure compliance. Using a system like InvoiceAdept can help you invoice customers professionally, track payments efficiently, and maintain records that are ready for Making Tax Digital (MTD) compliance.

Marketing and Business Expansion

As your window fitting business grows, consider diversifying your services to include related areas such as conservatory construction or bi-fold door installation. Expanding your service offerings can help you reach a broader customer base and increase your revenue. To support this, invest in marketing strategies that target both your existing and potential customers. Utilise social media platforms to showcase completed projects and customer testimonials. Attend local trade shows and home improvement fairs to network and promote your services.

Collaborating with other tradespeople can also open up new opportunities. For instance, partnering with electricians and plumbers on larger renovation projects can lead to repeat business and referrals. Always stay informed about industry trends and developments, as these can present new opportunities for your business.

Providing Excellent Customer Service

Delivering exceptional customer service is key to building a successful window fitting business. From the initial consultation to the completion of the installation, ensure that communication is clear and customer expectations are managed. Listen to your customers' needs and provide honest advice regarding the best solutions for their homes. After completing a job, follow up to ensure customer satisfaction and address any concerns promptly. A satisfied customer is more likely to recommend your services to others, contributing to the growth of your business over time.