How to Choose the Right Company for Your Glass Extension
A Discerning Buyer’s Framework: 25 questions to ask, red flags to avoid, and how to identify a company worthy of your trust and investment.
Quick Answer
Choose a company with: 10+ years trading history, verifiable completed projects, detailed written quotes, insurance-backed guarantees, proper accreditations (FENSA, GGF), and no high-pressure sales tactics. Get 3-4 quotes but don’t choose on price alone—compare specifications and evaluate the companies themselves.
Avoid companies that: pressure you to sign today, demand large deposits upfront (over 15%), won’t provide references, give vague verbal quotes, don’t discuss Building Regulations, or have no traceable business history. Trust your instincts—if something feels wrong, walk away.
The Discerning Buyer’s Checklist
- Trading history: Look for 10+ years in business with traceable records
- Fixed address: Established premises or showroom you can visit
- Portfolio: Real completed projects you can see (not just stock photos)
- References: Recent customers willing to speak with you
- Detailed quotes: Written, itemised, with clear specifications
- Insurance-backed guarantees: Protection if the company ceases trading
- Accreditations: FENSA, GGF, TrustMark, or equivalent
- Deposit: Maximum 10-15%, staged payments thereafter
- No pressure: Time to consider without “today only” discounts
- Building Regs: Clear explanation of compliance responsibilities
Why Choosing the Right Company Matters
A glass extension is a significant investment—typically £30,000 to £150,000+ depending on specification. You’re entrusting a company with your home, your money, and months of your life during the project. The difference between a good company and a poor one isn’t just the finished result; it’s the entire experience from first enquiry to final handover and beyond.
The conservatory and glass extension industry, like all home improvement sectors, has its share of excellent companies, mediocre operators, and outright rogues. The excellent companies deliver projects that exceed expectations, handle problems professionally, and leave customers genuinely delighted. The poor ones create stress, disappointment, and sometimes financial loss.
This guide will help you identify which is which before you commit.
A Note on Transparency
We’re Room Outside—a conservatory and glass extension company since 1973. Yes, we’d like you to consider us for your project. But more importantly, we want you to make a good decision, whoever you choose. A well-informed buyer asks better questions, recognises quality, and ultimately gets a better result. If we’re the right fit, that process will reveal it. If another company is better for your specific needs, you’ll discover that too.
Red Flags vs Green Flags
Some warning signs should end a conversation immediately. Others are positive indicators that suggest a company operates professionally. Here’s what to watch for:
Walk Away If You See These
- “Sign today” pressure: Discounts that expire when the salesperson leaves
- Large deposits: Requests for 30%+ upfront or full payment before completion
- No fixed address: PO Box only, no premises you can visit
- Cash discounts: Suggests tax avoidance and reduces your protection
- Won’t provide references: Reluctance to connect you with past customers
- Vague quotes: “About £X” without written specification
- No Building Regs discussion: Ignoring compliance responsibilities
- Pushy behaviour: Won’t leave until you sign, returns repeatedly
- Stock photos only: No real portfolio of their own work
- Recently formed company: Trading only 1-2 years (phoenix company risk)
Positive Indicators of Quality
- Established history: 10+ years trading under the same name
- Showroom: Physical premises you can visit and see products
- Genuine portfolio: Real projects with locations you could verify
- Happy to provide references: Confident in customer satisfaction
- Detailed written quotes: Itemised, with clear specifications
- No pressure: Encourages you to take time and compare
- Clear on Building Regs: Explains compliance and handles it for you
- Insurance-backed guarantees: Protection beyond the company itself
- Professional accreditations: FENSA, GGF, TrustMark, etc.
- Own installation teams: Employees, not rotating subcontractors
25 Questions to Ask Every Company
These questions reveal a company’s professionalism, capability, and trustworthiness. The answers—and how they’re delivered—tell you a great deal.
About the Company
How long have you been trading under this name?
Look for 10+ years. Shorter histories may indicate a “phoenix” company—reformed after previous failure.
What’s your registered business address?
Should be traceable premises, not just a PO Box. Can you visit?
Can I see your portfolio of completed projects?
Real projects with locations—not just stock images or renders.
Can I speak with recent customers or visit a completed project?
Confident companies welcome this. Reluctance is a red flag.
What accreditations and memberships do you hold?
FENSA, GGF, TrustMark, Which? Trusted Trader, ISO certifications.
About the Project
Who will design my project?
In-house designers vs. salesperson with a catalogue? Design expertise matters.
What materials do you use for frames?
Specific systems and manufacturers—not generic “aluminium” or “uPVC.”
What glazing specification do you use?
Glass type, U-values, solar control, manufacturer. Specifics indicate expertise.
Who handles Building Regulations and planning?
Should be clear on responsibilities and ideally handle this for you.
Do you use your own installation teams or subcontractors?
Own teams typically mean better quality control and accountability.
Who will be my point of contact throughout the project?
A dedicated project manager vs. “call the office” is preferable.
What’s included in the price?
Foundations? Electrics? Flooring? Decoration? Get clarity on inclusions.
What’s NOT included?
Exclusions are just as important. Hidden extras destroy budgets.
About Money and Protection
What deposit do you require?
10-15% is reasonable. Over 25-30% is a warning sign.
What’s the payment schedule?
Should be staged against milestones, not front-loaded.
When is the final payment due?
Should be on satisfactory completion—not before you’re happy.
What warranties do you offer?
Frame guarantee, glass unit guarantee, workmanship warranty—get specifics.
Are your guarantees insurance-backed?
Critical. Without this, a 25-year warranty is worthless if they close in year 3.
Who provides the insurance backing?
Should be a recognisable insurer you can verify.
About Problems and After-Care
What happens if something goes wrong during the build?
How do they handle problems? Clear process vs. vague assurances.
What’s your process for snagging and final inspection?
Formal sign-off process ensures issues are resolved before final payment.
How do I report problems after completion?
Clear after-care contact, not “call the mobile of whoever installed it.”
What’s your typical response time for warranty issues?
Specific commitment vs. “we’ll get to it when we can.”
What documents will I receive at completion?
Building Regs certificate, electrical certificate, warranties, manuals.
Can I see your standard contract?
Review before committing. Clear, fair terms indicate professionalism.
Understanding Quotes: Price vs Value
Getting multiple quotes is sensible—but comparing them requires care. The cheapest quote is rarely the best value, and sometimes the most expensive isn’t either.
What a Good Quote Should Include
Quote Checklist:
Why the Cheapest Quote Often Isn’t Cheapest
A significantly lower quote usually means one of these:
- Inferior materials: Cheaper frames, basic glazing, lower-spec hardware
- Missing items: Foundations, electrics, finishing work not included
- Less experienced installers: Cheaper labour, potentially lower quality
- No insurance backing: Warranty worthless if they go bust
- Extras added later: Low quote to win the job, then variations increase cost
The “Like-for-Like” Test
Before concluding one quote is better value, check they’re quoting the same thing. Compare:
- Frame system and manufacturer (not just “aluminium”)
- Glass specification and U-values
- Foundation type and depth
- Electrical scope (how many sockets, what lighting)
- Flooring inclusion or exclusion
- Internal finishes (plastering, decoration)
- Warranty length and insurance backing
A quote £15,000 lower that excludes foundations, electrics, and flooring isn’t actually cheaper.
Accreditations Worth Looking For
Trade accreditations indicate a company meets certain professional standards. Not all accreditations are equal—some are rigorous, others less so. Here are the meaningful ones:
FENSA
Government-authorised scheme for self-certifying window/door installations meet Building Regulations.
GGF
Glass and Glazing Federation—industry body with codes of practice and consumer protection.
TrustMark
Government-endorsed quality scheme. Requires financial checks and customer protection.
Which? Trusted Trader
Vetted by Which? with ongoing customer feedback monitoring.
Checkatrade
Verified reviews and basic vetting. Useful but less rigorous than TrustMark.
Manufacturer Approved
Authorised installer for specific systems (e.g., Schüco, Origin). Indicates training and support.
No accreditation guarantees perfection, but membership indicates a company is willing to meet external standards and be held accountable. Complete absence of any accreditations is concerning.
Warranties and Guarantees: What Really Protects You
Warranty claims are meaningless if the company has ceased trading—which is why insurance-backed guarantees (IBGs) are essential.
| Warranty Type | What It Covers | Typical Duration |
|---|---|---|
| Frame guarantee | Structural integrity, finish, hardware | 10-25 years |
| Sealed unit guarantee | Misting, failed seals in double/triple glazing | 5-10 years |
| Workmanship warranty | Installation defects, water ingress, settling | 2-10 years |
| Insurance-backed guarantee | Protection if installer ceases trading | 10-25 years |
The Insurance-Backed Guarantee Test
When a company offers an insurance-backed guarantee, verify:
- Who underwrites it? Should be a recognisable insurance company
- Can you get documentation? Certificate issued directly to you
- What’s actually covered? Read the terms, not just the headline
- Is the insurer legitimate? Check FCA register if unsure
A “25-year guarantee” from a company that might not exist in 5 years—without insurance backing—is worthless paper.
The Consultation: What to Observe
The initial consultation reveals much about how a company operates. Pay attention to:
Positive Signs
- Listening first: They ask about your needs before launching into a pitch
- Technical knowledge: Can answer questions about materials, Building Regs, thermal performance
- Honest about limitations: Will say “that won’t work” rather than promising everything
- No pressure: Comfortable with you getting other quotes and taking time
- Clear on process: Explains how the project would work from start to finish
- Brings samples: Shows actual materials, not just brochures
- Provides written quote: Detailed, to follow up after the visit
Warning Signs
- All talk, no listen: Pushes their agenda without understanding yours
- Vague on details: Can’t explain materials or specifications clearly
- Promises everything: No project constraints, no complications—suspicious
- Pressure tactics: “This price is only valid today,” “I need to call my manager”
- Won’t leave: Sits for hours, returns repeatedly, creates obligation
- Verbal quote only: Reluctant to put it in writing
- Disparages competitors: Professional companies focus on their own merits
Final Checklist: Before You Sign
Complete This Before Committing:
Peace of Mind: 10-Year Structural Warranty Included
About This Guide
This buyer’s guide draws on 50+ years of Room Outside’s experience in the conservatory and glass extension industry. The advice reflects our observations of what distinguishes reputable companies from problematic operators.
Last updated: March 2026 | Author: Room Outside
Frequently Asked Questions
How do I choose a good conservatory company?
Look for 10+ years trading history, verifiable portfolio, detailed written quotes, insurance-backed guarantees, trade accreditations (FENSA, GGF), and no high-pressure sales. Get 3-4 quotes and compare specifications, not just prices.
What questions should I ask a conservatory company?
Key questions: How long have you traded? Can I visit completed work? Who manages my project? What’s included/excluded? Who handles Building Regs? What warranties do you offer? Are guarantees insurance-backed? What’s the payment schedule?
What are the red flags when choosing a conservatory installer?
Warning signs: “Sign today” pressure, large deposits (over 15%), no fixed address, cash discounts, won’t provide references, vague quotes, no Building Regs discussion, pushy salespeople, stock photos only, recently formed company.
Should I get multiple quotes for a conservatory?
Yes, 3-4 quotes is advisable. But compare like-for-like specifications, check inclusions/exclusions, and evaluate the companies themselves. The cheapest quote often excludes items or uses inferior materials—rarely the best value.
What warranties should a conservatory company offer?
Look for: 10-year frame guarantee, 5-10 year sealed unit guarantee, workmanship warranty, and critically—insurance-backed guarantee protecting you if the company ceases trading. Verify the insurer is legitimate.
How much deposit should I pay for a conservatory?
10-15% deposit is reasonable, with staged payments at milestones (materials delivery, frame installation, completion). Be wary of 30%+ upfront or full payment before completion. Final balance should be on satisfactory completion only.
What accreditations should a conservatory company have?
Useful accreditations: FENSA (self-certifying installations), GGF membership, TrustMark (government-endorsed), Which? Trusted Trader, manufacturer approvals. These indicate professional standards and accountability.
Should I visit a conservatory showroom?
If possible, yes. Showrooms let you see build quality, glazing, and finishes firsthand. Companies with showrooms have invested in their business—a positive indicator. But excellent companies can operate without showrooms too.
Call us anytime – David, our digital assistant, will take a few details so the right specialist can follow up personally. 01243 538999 or request a consultation online
Ready to Find the Right Company?
We’ve been building glass extensions since 1973. We welcome your questions, encourage you to compare us with others, and are confident our answers—and our work—will speak for themselves.
Book Free ConsultationCall us anytime on 01243 538999 – David, our digital assistant, will take a few details so the right specialist can follow up personally.
Room Outside: Glass extension specialists since 1973.
Serving Kent, Surrey, Sussex, Hampshire, London & surrounding areas.
