SR4 Residential Steel Doors

LPS 1175 SR4 Residential Steel Door. The Commercial-Grade Upgrade Tier

LPS 1175 SR4 (D10 Issue 8). SteelR's Commercial-grade upgrade tier

The certification used on data centres and bank vaults. Available on residential specification by upgrade

LPS 1175 SR4 is the third tier in SteelR's four-tier security ladder. It sits above the SR3 Enhanced upgrade and below LPS 1673 attack-resistance. SR4 is the commercial-grade certification (D10 in the LPS 1175 Issue 8 rating matrix) used on data centre internal cores, bank vault outer doors, embassy and consul residences, and high-risk commercial premises. Available on any SteelR residential front door by upgrade. It is rarely seen on a private home, and it is offered for the small set of briefs where a documented threat profile, specialist insurer requirement, or owner preference for commercial-grade certification on the home justifies it.

This page explains what SR4 actually tests, how it differs from the SR3 Enhanced upgrade and the BS EN 1627 RC4 standard residential specification, who specifies SR4 on residential briefs in the UK, and how it integrates with the bespoke SteelR design language without compromising the external aesthetic.

The test itself

Longer attack duration, broader tool set, LPCB-certified

LPS 1175 SR4 (D10 Issue 8) testing is conducted by the Loss Prevention Certification Board (LPCB), part of BRE Global, a UKAS-accredited certification body. The methodology builds on the SR3 test by adding battery-operated cutting tools, larger crowbars, more aggressive prying equipment, and extending the attack duration. The complete door assembly is tested, including the frame, leaf, multi-point locking system, hinges and hardware. The whole assembly must resist the certified tool-and-time matrix to pass.
The threat model SR4 is designed to stop is not the opportunist burglar (which PAS 24 already addresses) and not the experienced burglar with hand tools (which RC4 and SR3 already address). SR4 addresses the determined attacker with a specific objective beyond the door, prepared to invest more time and a broader tool catalogue including power tools. This is the threat profile a commercial security manager designs for at a data centre or vault entrance. SR4 brings that level of certification to a residential front door.
Multi-point chrome locking mechanism on an SR4 rated steel front door

How SR4 compares

The four-tier residential security ladder

SteelR's residential security ladder runs across four certified tiers, each genuinely available on any bespoke door. The ladder allows the design consultation to match the cert to the brief, rather than offering a single inflexible specification.
For most homes, the standard residential specification meets the threat profile. For high-value properties, conservation areas, or insurer-mandated specifications, the Enhanced SR3 upgrade is appropriate. For threat- assessed properties, the Commercial-grade SR4 upgrade is appropriate. For documented ultra-high security briefs, LPS 1673 attack-resistance is available by enquiry. The full specification ladder sits on the security specification page.
  • Standard: PAS 24:2022 + BS EN 1627 RC4 single leaf unglazed (every SteelR door)
  • Enhanced: PAS 24 + RC4 + LPS 1175 SR3 (LPCB police-preferred scheme)
  • Commercial-grade: PAS 24 + RC4 + LPS 1175 SR4 D10 Issue 8 (data centres, bank vaults)
  • Ultra-high: PAS 24 + RC4 + LPS 1673 attack-resistance (AR.A300 / B180E / B300E / C120E)

The buyer profile

Who actually specifies SR4 on a residential brief

SR4 is genuinely a commercial certification. Its standard applications are bank vault doors, data centre internal cores, telecoms exchange and substation buildings, embassy and consul residences (where the building is part of asset protection), and high-value art or document storage. None of this is normal residential.
The legitimate residential audience for SR4 is small but real. SteelR specifies SR4 doorsets for the following categories of brief.
  • Properties with a documented threat assessment prepared by a private security advisor
  • Residences used by clients of specialist private banks or risk-focused insurers, where the underwriter has flagged a higher risk profile
  • Properties used as principal accommodation by clients in security-sensitive professions, including legal, political and senior financial roles
  • Homes with a constructed safe room or panic room behind the entrance, where SR4 forms part of a layered security plan
  • Family offices or private residences storing legal records, art or controlled documents
  • Owners who, having understood the difference between PAS 24, RC4, SR3 and SR4, decide they want commercial-grade certification on their home for the reassurance alone

Bespoke aesthetic, commercial-grade certification

Period proportions, conservation finishes, LPCB-certified internal assembly

A frequent concern about commercial-grade certification on a residential door is whether the door ends up looking commercial-grade. The answer is no. The certification attaches to the internal door assembly, frame integration, hardware specification and locking system. None of this is externally visible. A Georgian six-panel door in heritage racing green with solid brass hardware and a stained-glass fanlight is a viable SR4 specification. So is a contemporary flush leaf in matt anthracite with paired glazed sidelights.
Period panel mouldings, the full RAL colour palette, hardware finish options across polished chrome, brushed satin, antique brass, polished brass, matt black and brushed gold, and integrated sidelight, fanlight or overpanel configurations are all available within the SR4 product line. The certification does not impose a commercial aesthetic on the outside. Detailed coverage of design options sits on the RAL colours page.

Specification and lead time

Survey, design sign-off, certified manufacture and installation

SR4 specification follows the standard SteelR design process with one additional step. After the on-site survey, the design team confirms whether the brief justifies the Commercial-grade tier or whether SR3 (Enhanced) or the standard BS EN 1627 RC4 specification is the appropriate level. Where the property already has a documented threat assessment from a private security advisor, SteelR works directly with that advisor to align the specification with the wider security plan.
Lead time is ten to fourteen weeks from signed design to fitted installation, two to three weeks longer than the standard SteelR specification, reflecting the additional certification process and the supply-chain coordination required for the certified components. Pricing is individual to the project and is provided in writing within five working days of the survey. There are no fixed tiers and no published prices. The full process for non-SR4 specifications is described on the process page.

Continue Reading

Related reading

LPS 1175 SR3. Enhanced upgrade tier

The LPCB police-preferred specification. SteelR's Enhanced upgrade tier above the BS EN 1627 RC4 standard.

LPS 1673 attack-resistant steel doors

The LPCB attack-resistance certification beyond forced-entry resistance. Used on bank vaults and data centres. Available on residential specification by enquiry.

Full security specification ladder

PAS 24 + BS EN 1627 RC4 standard, LPS 1175 SR3 / SR4, LPS 1673 set out side by side.

Secured by Design steel front doors

The UK police-preferred specification, applied alongside PAS 24 and the LPS 1175 ladder.

Common Questions

Frequently asked questions

What does LPS 1175 SR4 mean on a residential steel door?

SR4 is Security Rating 4 under LPS 1175 Issue 8 (the D10 designation in the Issue 8 rating matrix), the Loss Prevention Certification Board scheme operated by BRE Global. It certifies that the door has been independently tested against a sustained forced-entry attack with a broader tool set including battery-operated cutting tools and larger prying equipment, for a longer attack duration than SR3. It is commercial-grade certification, used in data centres, bank vaults, embassy residences and high-risk commercial premises. SteelR offers SR4 as the Commercial-grade upgrade tier on any residential front door.

Who actually specifies SR4 on a residential door?

SR4 is rare on a private home, but the legitimate audience is real. Owners with a documented threat assessment from a private security advisor. Properties used by clients of specialist private banks where the underwriter has flagged a higher risk profile. Residences for security-sensitive professions including legal, political and senior financial roles. Properties with constructed safe rooms or panic rooms where SR4 sits behind the front door as part of a layered security plan. Owners who, having understood the difference between PAS 24, RC4, SR3 and SR4, decide they want the commercial-grade certification for the reassurance alone. For everyone else, the Enhanced SR3 upgrade or the BS EN 1627 RC4 standard residential specification is the appropriate answer.

How does SR4 differ from SR3 and from BS EN 1627 RC4?

BS EN 1627 RC4 (the European framework, single leaf, unglazed) is SteelR's standard residential specification. LPS 1175 SR3 is the Enhanced upgrade, the LPCB police-preferred scheme. LPS 1175 SR4 (D10 Issue 8) is the Commercial-grade upgrade above SR3. The differences are tool set and attack duration. SR4 testing adds battery-operated cutting tools, larger crowbars and a longer attack window to the SR3 methodology. The result is a certification that materially exceeds residential threat models and addresses commercial-grade asset protection. The four-tier ladder is: PAS 24 plus RC4 standard, SR3 enhanced, SR4 commercial-grade, LPS 1673 ultra-high.

Does SR4 affect the look or design of the door?

No. The SR4 certification attaches to the internal door assembly, frame integration, hardware specification and locking system, not the external aesthetic. A Georgian six-panel door in a heritage colour with brass hardware is a viable SR4 specification. So is a contemporary flush leaf in matt anthracite. Period proportions, the full RAL colour palette, hardware finish options and integrated sidelight or fanlight configurations are all available within the SR4 product line. The certification operates inside the door; it does not impose a commercial aesthetic on the outside.

How is SR4 specified and what is the lead time?

SR4 follows the standard SteelR design process with one additional step. After the on-site survey, the design team confirms whether the brief justifies the Commercial-grade tier or whether SR3 (Enhanced) or the standard BS EN 1627 RC4 specification is more appropriate. Lead time is ten to fourteen weeks from design sign-off to fitted installation, two to three weeks longer than the standard SteelR specification, reflecting the additional certification process and the supply chain coordination required for the certified components. Pricing is individual to the project. There are no fixed tiers and no published prices.

PAS 24 CertifiedBS EN 1627 RC4 StandardLPS 1175 SR3 / SR4 AvailableLPS 1673 on EnquirySecured by DesignFD30S / FD60 Fire RatedISO 9001 + ISO 14001Made in Britain

Bespoke · UK manufactured · BS EN 1627 RC4 · LPS 1175 SR3 / SR4 available

Enquire about a bespoke SteelR door for LPS 1175 SR4 Commercial-Grade Steel Doors

Free consultation with our design team. No obligation. Every door is manufactured in the UK to your specification. Standard residential spec is BS EN 1627:2011 RC4 single leaf, unglazed. LPS 1175 SR3 and SR4 enhanced and commercial-grade certifications are available on request, with LPS 1673 attack-resistance by enquiry. Installed by our in-house fitters.

Call us
0800 861 1450
BS EN 1627 RC4 standard · LPS 1175 SR3 / SR4 available · PAS 24 · Secured by Design · UK manufactured · 10-year guarantee

Or request a call-back

No obligation. We respond within 24 hours, weekdays.

Specify a Commercial-grade SR4 residential door

Request a Consultation