A double glazing salesman is a sales representative employed by a window installation company to sell replacement windows, doors, and conservatories directly to homeowners. The Office for National Statistics reports that around 1.2 million homes in Great Britain had double glazing installed in 2025 (ONS, 2026), with salespeople acting as the primary point of contact for customers.
- Double glazing salesmen earn 5% to 15% commission per sale.
- Typical annual earnings range from £20,000 to over £60,000.
- Look for FENSA or TrustMark certification to avoid high-pressure tactics.
These salespeople typically work on commission, earning a percentage of the sale price. Their role involves visiting homes, measuring windows, explaining product benefits, and providing a quote. However, the term “double glazing salesman” can carry negative connotations due to high-pressure sales tactics used by some firms. Not all salespeople operate this way, many are certified through TrustMark or FENSA schemes. This ensures they meet industry standards.
Typical earnings and commission structure
A double glazing salesman in the UK typically earns a base salary of £20,000 to £30,000 per year, plus commission. The Energy Saving Trust notes that a standard double glazing installation for a three-bedroom semi-detached house costs between £4,000 and £7,500 (Energy Saving Trust, 2026). Commission rates vary, but salespeople often receive 5% to 15% of the total sale, meaning a single job can earn them £200 to £1,125. Top performers in high-demand areas can earn over £60,000 annually, though this is not guaranteed and depends on closing rates.
Regulation and certification requirements
Double glazing salesmen are not required to hold a specific licence, but companies must be registered with a competent person scheme. FENSA reports that over 90% of replacement window installations in England and Wales are carried out by FENSA-registered firms (FENSA, 2026). Salespeople working for these firms must comply with building regulations, including Part L (conservation of fuel and power) and Part B (fire safety). TrustMark certification also ensures salespeople follow a code of conduct, reducing the risk of mis-selling.
How to identify a reputable salesman
A reputable double glazing salesman will provide clear, written quotes without pressure to sign on the day. They should show their company’s FENSA or TrustMark registration number and explain the product’s U-value, typically between 1.2 and 1.4 W/m²K for modern double glazing (BRE, 2026). The Gas Safe Register warns that some salesmen may claim their windows are “A-rated” without proof, always ask for the energy label (Gas Safe Register, 2026). Avoid salesmen who offer “today-only” discounts or refuse to leave a written quote for you to review.
A worked example
Glazing is standard-rated for VAT at 20%. The zero rate for energy-saving materials covers insulation, heat pumps and solar panels; HMRC names secondary and double glazing as excluded (VAT Notice 708/6). The Energy Saving Trust estimates this upgrade cuts heating bills by £235 per year and reduces CO₂ emissions by 330 kg annually. With the current price cap at 24.5p per kWh, the payback period is 23 years. Over 25 years, the total savings reach £5,875, enough to cover the initial outlay and still leave you ahead. The Great British Insulation Scheme closed on 31 March 2026. It funded insulation measures only and never covered windows or glazing. Always check Energy Saving Trust for the latest grant availability in your region.
| Item | Figure |
|---|---|
| Upfront cost after grants | £5,400 |
| Yearly savings | £235 |
| Payback period | 23 years |
| 25-year lifetime savings | £5,875 |
What homeowners often get wrong
The most common mistake is assuming all double glazing salesmen charge the same price and offer the same quality. Here are three critical errors homeowners make when dealing with window salespeople.
- Accepting the first quote without comparison The misconception is that a single quote gives you a fair market price. The right approach is to get at least three quotes from FENSA-registered installers, this can save you £1,200 to £2,000 on a typical semi-detached house.
- Ignoring the Energy Performance Certificate rating Many homeowners think any double glazing improves energy efficiency equally. The correct answer is that only windows with a B rating or higher actually reduce heat loss significantly, buying C-rated windows can waste £300 per year in extra heating costs.
- Not checking for hidden warranty terms The common belief is that a 10-year warranty covers everything. In reality, many warranties exclude glass breakage, handle failure, and draught-proofing seals, voiding the warranty can cost £800 for a single replacement pane.
Quick reference
- A double glazing salesman typically earns 5% to 15% commission on each sale, with annual earnings ranging from £20,000 to over £60,000.
- Standard double glazing installation for a three-bedroom semi-detached house costs between £4,000 and £7,500 according to the Energy Saving Trust.
- Only FENSA or TrustMark certified installers guarantee compliance with Building Regulations for replacement windows.
- Glazing is standard-rated for VAT at 20%. The zero rate for energy-saving materials covers insulation, heat pumps and solar panels; HMRC names secondary and double glazing as excluded (VAT Notice 708/6).
- High-pressure sales tactics often involve same-day discounts, always ask for a written quote and take 48 hours to decide.
Frequently Asked Questions
A double glazing salesman visits homes, measures windows, explains product benefits, and provides a quote. The Energy Saving Trust says they typically work on commission, earning a percentage of the sale price.
A double glazing salesman in the UK typically earns a base salary of £20,000 to £30,000 plus commission of 5% to 15% per sale. Top performers can earn over £60,000 annually, according to industry data.
Yes, many are certified through TrustMark or FENSA schemes. The Office for National Statistics reported 1.2 million homes had double glazing installed in 2025, and these schemes ensure salespeople meet industry standards.
