Choosing a door installer is about more than price, it affects your home’s security, energy efficiency, and legal compliance. The wrong installer can leave you with draughts, poor insulation, or a door that fails building regulations. These ten questions will help you separate qualified professionals from cowboys before you commit.
Before hiring any door installer, always ask for proof of FENSA or Certass registration to guarantee building regulations compliance. This single check confirms your new door meets thermal and security standards without requiring separate local authority approval.
What matters when you choose: focus on compliance, security, and energy performance, not just the lowest quote. An unregistered installer may seem cheaper upfront but can cost you hundreds in retrospective building control fees and remedial work.
| Question category | Key question | Why it matters | Who to verify with |
|---|---|---|---|
| Compliance | Are you FENSA/Certass registered? | Avoids fines and re-inspection costs | FENSA, Certass |
| Security | Do you use Secured by Design products? | Improves home security | Secured by Design |
| Energy | What U-value will the door achieve? | Affects heating bills | Energy Saving Trust |
| Installation | Do you provide a written guarantee? | Protects against poor workmanship | TrustMark |
| Compliance | Will you self-certify the installation? | Saves local authority notification fees | FENSA |
| Energy | How will this affect my EPC rating? | Can improve property value | Energy Saving Trust |
| Security | Does the door meet Part Q standards? | Legal requirement for external doors | GOV.UK |
| Workmanship | Can you provide customer references? | Shows track record of quality | TrustMark |
| Cost | Is your quote fully itemised? | Prevents surprise charges later | TrustMark |
| Performance | How do you seal against draughts? | Reduces heat loss and condensation | Energy Saving Trust |
1. Ask for FENSA or Certass registration
FENSA and Certass are the two government-approved competent person schemes for door installation in England and Wales. An installer registered with either scheme can self-certify that your new door meets building regulations, removing the need for a separate local authority inspection and fee (GOV.UK, competent person schemes, 2026). Without this registration, you may face a retrospective building control application costing around £200–£400.
- Check the installer’s name against the FENSA or Certass online register before work starts.
- Unregistered installers may offer lower prices but leave you liable for compliance costs.
- Registration also covers insurance-backed guarantees for added protection.
2. Confirm Secured by Design certification
Doors with Secured by Design accreditation meet police-approved security standards tested to resist forced entry. This certification covers the door construction, locks, hinges, and glazing as a complete system (Secured by Design, 2026). Insurance providers often recognise Secured by Design products, which can reduce your home insurance premium.
- Ask to see the Secured by Design certificate for the specific door model being fitted.
- Standard PAS 24 or TS 007 locks are good, but Secured by Design goes further.
- A certified door typically includes multi-point locking and reinforced hinges.
3. Request the door’s U-value rating
The U-value measures how much heat passes through the door. A lower number means better insulation. For a composite door, a U-value below 1.6 W/m²K indicates good thermal performance, while high-performance models can reach 1.2 W/m²K or lower (Energy Saving Trust, doors advice, 2026). This matters because a poorly insulated door can increase your heating bills.
- Ask for the U-value in writing as part of the product specification.
- Compare U-values across quotes to see which door will save you more energy.
- Solid timber doors typically have higher U-values than composite or uPVC alternatives.
4. Ask about the guarantee period
Most reputable installers offer a 10-year guarantee on parts and workmanship, covering issues like warping, lock failure, and seal deterioration. TrustMark-registered tradespeople must provide clear guarantee terms (TrustMark, 2026). A shorter guarantee may signal lower confidence in the product or installation quality.
- Get the guarantee terms in writing, including what is and is not covered.
- Check whether the guarantee is backed by insurance if the installer ceases trading.
- Some guarantees exclude labour after the first year, so read the small print.
5. Check if they handle building regulations notification
FENSA or Certass registered installers self-certify compliance with building regulations, which means they notify your local authority automatically after installation. This saves you a separate notification fee of around £100–£200 and avoids delays when selling your home (FENSA, 2026). If the installer cannot self-certify, you must arrange your own building control approval.
- Ask the installer to confirm they will self-certify as part of the quote.
- Without self-certification, you may need a retrospective inspection that costs more.
- Keep the certificate of compliance for your property records.
6. Inquire about energy performance certificate impact
A new door with a low U-value can improve your home’s Energy Performance Certificate (EPC) rating by up to 2 points, depending on the existing door condition and overall property efficiency (Energy Saving Trust, EPCs, 2026). This can increase your property’s market value and make it more attractive to buyers.
- Ask the installer for the door’s EPC impact estimate based on your property type.
- Replacing an old, draughty timber door with a modern composite door gives the biggest gain.
- An improved EPC rating can also unlock better mortgage deals or green loan rates.
7. Confirm the door meets Part Q security requirements
Building regulations Part Q requires external doors to resist physical attack for at least 3 minutes, tested to the PAS 24 or equivalent standard (GOV.UK, Approved Document Q, 2026). This is a legal requirement for new or replacement doors in England. An installer who cannot confirm Part Q compliance may be fitting non-compliant products.
- Ask for the product’s test certificate showing PAS 24 or LPS 1175 compliance.
- Part Q applies to all external doors, including back and side doors.
- A compliant door typically has multi-point locks, anti-pick cylinders, and reinforced glass.
8. Ask for references from recent jobs
Checking two or three customer references helps verify the installer’s reliability, finish quality, and punctuality. TrustMark recommends asking for references from jobs completed within the past 12 months (TrustMark, 2026). Online reviews can be helpful, but direct references give more honest feedback.
- Ask for references for similar door types (composite, uPVC, timber) to your project.
- Contact the references and ask about the installation process and aftercare.
- If the installer hesitates to provide references, treat it as a red flag.
9. Request a detailed written quote including all costs
A transparent quote should list door, frame, ironmongery, fitting, disposal of old door, and any additional fees separately. TrustMark advises that itemised quotes prevent surprise charges later (TrustMark, 2026). Vague quotes that bundle everything into one price make it hard to compare offers fairly.
- Ensure the quote includes VAT, delivery, and any structural adjustments needed.
- Ask about disposal fees for your old door, some installers charge extra.
- Compare at least three itemised quotes before making a decision.
10. Ask about draught-proofing and weather sealing
Poorly sealed doors can account for up to 15% of heat loss in a typical home, according to the Energy Saving Trust (Energy Saving Trust, draught-proofing, 2026). Ask the installer what type of weather seals they use and whether the door includes a threshold seal. Quality seals reduce draughts, condensation, and noise.
- Look for dual-compression or magnetic seals that form a tight barrier.
- Check that the threshold seal is adjustable to account for floor settlement.
- Poor seals can also let in rainwater, leading to damp and rot over time.
Asking these ten questions before you hire means you get a door that is secure, energy-efficient, and legally compliant. how to choose the right front door material and understanding door U-values and energy ratings can help you compare product options further. A few minutes of checks now can save you years of regret and expense.
Frequently Asked Questions
Ask 10 key questions: Are you FENSA or Certass registered? Do you use Secured by Design products? What U-value will the door achieve? Do you provide a written guarantee? Will you self-certify the installation? How will this affect my EPC rating? Does the door meet Part Q standards? Can you provide customer references? Is your quote fully itemised? How do you seal against draughts? These cover compliance, security, and energy performance.
FENSA registration ensures your door installer can self-certify compliance with building regulations, avoiding separate local authority fees. According to GOV.UK, this saves you from retrospective inspection costs and fines, which can run into hundreds of pounds.
A new external door should achieve a U-value of 1.6 W/m²K or lower for good energy efficiency, per Energy Saving Trust guidelines. Lower U-values mean less heat loss, reducing your annual heating bills by up to £100.
Yes, external doors must meet Part Q of building regulations for security, as stated by GOV.UK. Ask your installer if the door meets Part Q standards to ensure legal compliance and protect against break-ins.
Check registration with FENSA or Certass directly on their official websites. Also verify TrustMark accreditation for workmanship guarantees and Secured by Design certification for security products. These checks confirm professional standards.
