Author: Very Secure Doors
Last Updated: 24th March 2026
When choosing a new composite door, three brands consistently stand out in the UK market: Rockdoor, Solidor, and Endurance. Each manufacturer has built a strong reputation, but they take different approaches to security, thermal efficiency, and customisation.
As official Rockdoor Trusted Installers with over 2,000 door installations since 2010, we’re frequently asked how these brands compare. This guide examines the key differences to help you make an informed decision based on your priorities.
We’ll compare:
- Security features and locking systems
- Thermal efficiency and energy ratings
- Customisation options and design ranges
- Price positioning and value for money
This comparison uses manufacturer specifications and our hands-on installation experience with these three brands. While we specialise in Rockdoor installations, we’ve researched all three brands thoroughly to provide an accurate, balanced comparison.
Whether security is your top priority, you need extensive customisation options, or you’re looking for the best value, this guide will help you choose the right composite door for your home.
Quick Comparison: Rockdoor vs Solidor vs Endurance
Here’s a snapshot of how these three premium composite door brands compare across key features. Detailed explanations follow below.
| Feature | Rockdoor | Solidor | Endurance |
|---|---|---|---|
| Core Type | High-density polyurethane foam | Solid timber | Solid engineered timber (17 LVL layers) |
| Sash Thickness | 50mm | 48mm | 48mm |
| Frame Material | 72mm Rehau with steel reinforcement | 70mm Kommerling uPVC with plastic reinforcement | 72mm Rehau uPVC with plastic reinforcement |
| Standard Lock | Avocet ATK 3-star | Ultion 3-star | Avocet ABS Master 3-star |
| Locking Mechanism | Winkhaus 2-hook (4-hook upgrade) | Avantis multipoint (25mm deadbolt) | Guardian5 multipoint (5 deadbolts) |
| Security Focus | Highest (steel-reinforced frame) | High (largest deadbolt) | High (5-point locking) |
| Thermal Rating | A-C (up to A rating) | U-value 1.1-1.5 W/m²K | U-value 1.4 W/m²K |
| Thermal Tech | S-Glaze (sealed glazing) | Solid timber insulation | CoolSkin + 17-layer core |
| Door Styles | 30 styles | 30+ styles | 85+ styles |
| Colour Options | 14 colours | 27 colours | 19 colours |
| Customisation | Quality-focused | Good variety | Most extensive range |
| Price Range | ££££ (Premium) | ££££ (Mid-Premium) | ££££ (Mid-Premium) |
| Best For | Maximum security & quality | Eco-friendly & colour choice | Customisation & design variety |
| Warranty | 10-year door, 5-year locks/hardware | 10-year door, 5-year hardware | 10-year door |
History of Each Brand
Understanding each brand’s background provides valuable context for their design philosophy and manufacturing approach.
Rockdoor was established in 1996 in Blackburn, Lancashire, with a singular focus on creating the most secure composite door on the market. From the beginning, the company prioritised security features and advanced manufacturing techniques, pioneering innovations like S-Glaze technology and steel-reinforced frames. Today, Rockdoor remains focused on premium security and quality over extensive design variety.
Solidor was founded in 2004 in Stoke-on-Trent with a commitment to eco-friendly manufacturing. The brand became known for its solid timber core construction and sustainable approach, using recycled materials in their frame reinforcement. Solidor has built a reputation for offering extensive colour options and design flexibility while maintaining high security standards.
Endurance Doors began operations in 2002 in Lincoln (as part of the Rocal Group), focusing on providing homeowners with maximum customisation options. The company developed a unique 17-layer laminated veneer lumber core and introduced innovations like the Moisture Barrier System. Endurance has grown to offer the widest range of door styles among premium composite door manufacturers, with over 85 designs across three distinct collections.
Security Features: How They Compare
Security is often the primary consideration when choosing a composite door. All three brands deliver excellent protection, but their approaches differ significantly. Here’s how Rockdoor, Solidor, and Endurance compare across key security elements: lock cylinders, locking mechanisms, door construction, and frame reinforcement.
Rockdoor: Maximum Security Engineering
Rockdoor’s security-first philosophy is evident throughout its construction. The combination of a steel-reinforced 72mm Rehau frame and 50mm high-density polyurethane core creates exceptional resistance to forced entry. Independent testing shows Rockdoor doors are 35% stronger than typical GRP composite doors.
The standard security package includes an Avocet ATK 3-star cylinder, offering protection against lock snapping, bumping, and drilling. The German-engineered Winkhaus multipoint locking mechanism features a 2-hook system as standard, with an optional upgrade to 4-hook configuration for enhanced security. These nickel-plated hooks engage with steel keeps in the reinforced frame, creating multiple secure contact points.
What sets Rockdoor apart is the steel reinforcement throughout the outer frame. This allows hinges and locking components to anchor into steel rather than plastic, creating a connection that’s over 50% stronger than competitors. The door also features S-Glaze technology, which permanently seals glazing units into the door sash, eliminating a common vulnerability point.
For homeowners prioritising security above all else, Rockdoor’s comprehensive security features make it the strongest option available.
Solidor: Solid Timber Core Strength
Solidor takes a different approach with its 48mm solid timber core, providing inherent strength and durability. The timber construction creates excellent resistance to impact and forced entry attempts.
Security features include the Ultion 3-star cylinder as standard, backed by a £5,000 break-in guarantee. The Ultion features Lockdown Mode technology that activates during forced entry attempts, making it exceptionally difficult to compromise.
The Avantis multipoint locking mechanism is exclusive to Solidor and features the industry’s largest deadbolt at 25mm triangular design. This provides exceptional compression and security when the door is closed. The multipoint system includes hooks and deadbolts that engage at multiple points along the 70mm Kommerling uPVC frame, which uses plastic (Werbar) reinforcement rather than steel.
While the frame reinforcement isn’t steel, Solidor’s combination of solid timber core and advanced locking systems delivers high security that meets Secured by Design standards.
Endurance: Engineered Timber Security
Endurance doors feature a 48mm solid engineered timber core constructed from 17 cross-laminated veneer lumber layers. This laminated construction provides excellent dimensional stability and resistance to warping, while also delivering strong security performance.
The standard lock cylinder is the Avocet ABS Master 3-star, which offers protection against snapping, drilling, and picking. Endurance has recently introduced the Guardian5 multipoint locking mechanism, featuring five 20mm nickel-plated deadbolts that engage into steel keeps. This replaced the previous TruLock system and represents a significant security upgrade.
The door frame uses 72mm Rehau uPVC profile with plastic reinforcement—the same frame profile as Rockdoor but without steel reinforcement. Endurance doors also feature a Moisture Barrier System at the base to protect the timber core from water ingress, which helps maintain long-term structural integrity and security performance.
Endurance doors achieve Secured by Design certification when paired with laminated glass and high-security cylinders.
Security Verdict
All three brands deliver excellent security that far exceeds standard compositedoors. The key differences lie in frame reinforcement and core materials:
Rockdoor offers the highest security level with steel-reinforced frames, 50mm sash thickness, and comprehensive anti-attack features. The steel reinforcement creates the strongest possible anchor points for hinges and locks.
Solidor’s solid timber core and 25mm deadbolt provide excellent security, though the plastic-reinforced frame doesn’t match steel’s strength.
Endurance delivers strong protection with its 17-layer engineered core andGuardian5 5-point locking, but like Solidor, uses plastic rather than steel frame reinforcement.
For maximum security, Rockdoor’s steel-reinforced construction provides the strongest defence against forced entry.
Thermal Efficiency: Keeping Your Home Comfortable
Thermal efficiency determines how well your composite door prevents heat loss in winter and heat gain in summer. With UK Building Regulations requiring doors to achieve a U-value of 1.4 W/(m²·K) or better for existing dwellings, all three brands meet this standard—but they take different approaches.
Rockdoor Thermal Performance
Rockdoor achieves Door Set Energy Ratings between A and C depending on specification.
The brand’s thermal advantage centres on S-Glaze technology. Rather than using traditional clip-on cassettes prone to draughts and heat loss, S-Glaze permanently seals the glass unit between the door skins during manufacturing. This eliminates the glazing aperture as a weak point for thermal performance.
Additional thermal features include a 50mm thick sash, Q-lon gasket, high-density polyurethane foam core, and thermally efficient PVC-U skins that work together to achieve industry-leading thermal ratings. The 72mm Rehau frame with aluminium reinforcement provides excellent structural integrity whilst maintaining thermal performance.
For homeowners prioritising maximum energy efficiency, Rockdoor recommends solid door styles or models with clear backing glass to achieve the best possible Door Set Energy Rating of A Rockdoor.
Solidor Thermal Performance
Solidor doors achieve U-values between 1.1 and 1.5 W/(m²·K), comfortably exceeding the 1.4 W/(m²·K) Building Regulations standard. The brand’s thermal performance stems from its 48mm solid timber core—a natural insulator that offers stable thermal properties.
The 70mm Kommerling uPVC frame incorporates Werbar recycled plastic reinforcement, which provides superior thermal performance compared to steel or aluminium whilst also being environmentally friendly. This frame construction contributes to excellent screw retention and reduces thermal bridging.
Thermal efficiency can be enhanced further by specifying laminated glass, which adds an additional layer of insulation whilst also improving security. The solid timber construction naturally resists heat transfer, and doors are proven to contribute to reduced heating costs when replacing older timber or basic composite doors.
Endurance Door Thermal Performance
Endurance doors meet Building Regulations with a U-value of 1.4 W/(m²·K), achieved through their distinctive 17-layer engineered timber core construction.
The brand’s standout thermal feature is CoolSkin technology, which reflects up to 90% of solar heat. This addresses a common composite door challenge: dark colours (particularly Anthracite Grey and Black) absorbing excessive heat in direct sunlight. CoolSkin prevents the heat build-up that can cause bowing whilst maintaining colour stability Endurance.
Endurance’s glazing units incorporate 4mm soft coat glass panes filled with 90% argon gas—a denser-than-air insulator that reduces heat transfer through the glazed areas. Argon gas is 38% denser than air, significantly limiting molecular movement and thermal conduction between panes.
The 72mm Rehau frame and Moisture Barrier System at the door base provide additional thermal protection whilst preventing water ingress that could compromise insulation.
Thermal Efficiency Verdict
All three brands exceed Building Regulations requirements, but with different strengths:
Rockdoor is the most comprehensive draught elimination through S-Glaze technology. For homeowners seeking maximum thermal performance, particularly with glazed designs, Rockdoor’s permanent glazing seal provides measurable advantages. Explore the full Rockdoor range we install
Solidor offers excellent thermal performance (1.1-1.5 U-values) through natural timber insulation, with the added benefit of recyclable, environmentally-friendly frame reinforcement.
Endurance meets the standard (1.4 U-value) whilst excelling in heat-reflective technology—particularly valuable for south-facing doors or dark colour finishes exposed to direct sunlight.
For most UK homeowners, the thermal performance differences translate to minor variations in annual energy costs. Truth be told, all three brands are exceptional when it comes to thermal performance and will substantially outperform older timber or basic composite doors.
Customisation Options: Making Your Door Unique
All three brands offer extensive customisation to match your home’s style, but they take different approaches to design flexibility.
Rockdoor Customisation
Rockdoor offers 30 different door styles spanning traditional, contemporary, and cottage designs. The range includes 14 colours, with the latest addition being Pebble Grey (RAL 7032) launched in 2024. Popular choices include Anthracite Grey, Slate Grey, Chartwell Green, and woodgrain finishes like Irish Oak and Light Oak.
Rockdoor’s dual-colour option allows different colours for internal and external faces, creating 196 possible combinations. This lets you match the door’s exterior to your home’s facade whilst coordinating the interior with your hallway décor—particularly useful in open-plan homes.
Rockdoor offers exclusive 3D glass designs with genuine dimensional textures and bevelling, not flat printed patterns. The brand’s online 3D door designer allows you to visualise your chosen door on a photo of your actual home before ordering.
Solidor Customisation
Solidor’s range divides into two main collections: the Italia Collection featuring 24 contemporary Italian-inspired designs, and the Traditional Collection with classic styles. This gives homeowners over 30 styles to choose from overall.
Solidor offers 27 colour options, including authentic woodgrain effects and modern shades. The brand’s dual-colour capability allows different internal and external finishes.
Solidor’s handmade Warwick Glass designs offer unique pieces where no two panes are identical, created through a random pattern manufacturing process. Frame options include both chamfered (clean, modern lines) and sculptured (traditional decorative) profiles.
Endurance Customisation
Endurance organises its range into four distinct collections: Classic Collection (20 Georgian/Victorian-inspired designs), Urban Collection (10 modern styles), Country Collection (traditional shiplap styles), and the Avantal Collection (avant-garde contemporary designs). This gives homeowners over 80 unique door designs to choose from—the widest range of the three brands.
Endurance offers 19 colours organised into thematic collections (Black Collection, Blue Collection, Grey Collection, etc.), with dual-colour options for internal/external faces. The brand’s CoolSkin technology makes dark colours like Schwarz Braun Black more practical by preventing heat-related bowing.
All three brands offer extensive hardware choices including handles, knockers, letterplates, and hinges in finishes from polished chrome to matte black.
Customisation Verdict
Endurance offers the widest style selection (80+ designs across four collections), making it ideal for homeowners wanting extensive choice or unique designs.
Solidor balances selection (30+ styles) with premium touches like handmade Warwick Glass, appealing to those seeking distinctive, artisan elements.
Rockdoor focuses on practical versatility with 30 styles, 14 colours, and 196 dual-colour combinations, plus the industry’s best visualisation tool for seeing your chosen door on your actual home.
For most homeowners, all three brands offer sufficient choice. Your decision will likely come down to whether a specific style you love is available or colour, rather than the total number of options.
Price & Value: What to Expect
Composite door pricing varies significantly based on specification, but all three premium brands sit in a similar price bracket—substantially higher than budget alternatives, yet justified by superior construction and longevity.
Typical Pricing (Fully Fitted, 2025-2026)
Based on installer quotes and market research:
Rockdoor
£1,500–£2,500+ fully fitted including VAT. A standard Rockdoor Vermont in white starts from £1,500, but once you add premium glass designs, bar handles (316L marine-grade stainless steel), and dual-colour options, expect £500–£1,000 on top. For a full breakdown of what affects the price, see our Rockdoor prices.
Solidor
£1,200–£3,000 depending on customisation, with typical installations ranging £1,200–£1,800. Basic configurations start around £1,200, whilst premium Italia designs with handmade Warwick Glass and stainless steel hardware reach £2,000+
Endurance
£1,300–£2,500+ fully fitted. Standard doors typically cost £1,300–£1,600, with complex specifications (stable doors, multiple sidelights, premium hardware) reaching £2,500 or higher.
All three brands use premium materials—Rockdoor and Endurance both specify Rehau outer frames, considered among the best in the industry, whilst Solidor uses Kömmerling profiles. Budget composite doors (£800–£1,200) typically compromise on frame quality, hardware, and core construction.
What Drives Cost Differences?
Price variations within each brand reflect:
- Glass design complexity – Decorative leaded glass costs £200–400 more than plain
- Hardware upgrades – Marine-grade stainless steel bar handles add £150–300
- Sidelights/toplights – Each panel adds £300–600 depending on glass
- Dual colours – Internal/external colour differences add £100–200
- Installation complexity – Period properties with thick timber frames require more labour
Price Verdict
Expect to pay a typical £1,500–£2,000 for a well-specified door from any of these brands. Rockdoor typically commands the highest prices due to brand positioning and steel reinforcement options, whilst Endurance and Solidor offer comparable value with minor price advantages depending on specification.
Final Verdict: Which Brand Is Right for You?
All three brands deliver exceptional composite doors that vastly outperform budget alternatives. Your choice should align with your specific priorities:
Choose Rockdoor if: You prioritise maximum security above all else. The steel-reinforced frame, 50mm sash, and S-Glaze technology provide measurably superior protection. Best for security-conscious homeowners, properties in higher-crime areas, or anyone wanting absolute peace of mind. The premium price reflects genuinely premium construction.
Choose Solidor if: You value solid timber construction and environmental credentials. The 48mm solid timber core offers authentic quality, whilst Werbar recycled frame reinforcement appeals to eco-conscious buyers. Ultion’s £5,000 guarantee provides exceptional lock security. Ideal for homeowners seeking traditional craftsmanship with modern performance.
Choose Endurance if: You want the widest style selection and best value for customisation. With 80+ designs across four collections and CoolSkin technology that prevents dark-colour bowing, Endurance excels in design flexibility. Perfect for homeowners with specific aesthetic requirements or south-facing installations in dark colours.
All three brands justify their premium pricing through superior materials, comprehensive warranties, and 30+ year lifespans. You cannot make a bad choice—any of these doors will transform your home’s security, thermal efficiency, and kerb appeal for decades to come.
Ready to upgrade? Explore our Rockdoors to see how we can help transform your home’s entrance with the UK’s most secure composite door.
Rockdoor is the strongest overall for security. It’s the only brand that combines a 360° aluminium-reinforced inner frame, S-Glaze technology (glass permanently sealed into the door with no removable cassettes), and an optional welded steel mesh upgrade. Rockdoor holds PAS 24 certification and Secured by Design accreditation is available when specified with laminated glass and steel mesh. Solidor and Endurance both offer PAS 24 compliant doors with Ultion and ABS 3-star cylinders respectively, but neither matches Rockdoor’s structural reinforcement or glazing security.
They’re different doors built for different priorities. Solidor uses a 48mm solid timber core which gives it a heavier, more substantial feel and offers the widest colour range (27+ colours with dual-colour options). Rockdoor uses a high-density foam core with a 360° aluminium inner frame and S-Glaze sealed glazing, making it structurally stronger and more secure. In our experience fitting both, Rockdoor has fewer long-term issues with thermal movement and weatherproofing. Solidor edges it on design flexibility and colour choice.
All composite doors experience minor thermal movement in direct sunlight — no manufacturer can eliminate this entirely. However, Rockdoor’s 360° aluminium inner frame restricts movement significantly compared to timber-core alternatives like Solidor and Endurance. Rockdoor backs this with a 3mm no-bow guarantee. In our experience fitting Rockdoors since 2010, any movement we’ve seen has been slight and has had no effect on the door’s operation or weatherproofing. For south-facing doors, we recommend lighter colours to minimise heat absorption.
All three brands should last 20+ years with proper maintenance. Rockdoor offers a 10-year guarantee on the door slab, outerframe and double-glazed unit. Solidor offers a 10-year guarantee, and Endurance offers a 10-year guarantee. In practice, the door slab itself rarely fails — it’s the hardware (handles, locks, seals) that wears first, typically after 8–12 years. All three brands use replaceable hardware, so worn components can be swapped without replacing the whole door.
It depends on your priorities. GRP composite doors (Door-Stop, Hallmark) offer the best value from around £1,100 fitted if security beyond standard multipoint locking isn’t a major concern. For premium brands, Solidor starts from around £1,200 fitted and offers excellent customisation. Rockdoor starts from £1,500 fitted but includes features no other brand offers as standard — S-Glaze sealed glazing, aluminium inner frame, and a 3mm no-bow guarantee. Most of our customers spend between £1,900 and £2,100 on a Rockdoor once they’ve chosen their colour, glass and hardware.
Each brand offers different colour ranges. Rockdoor has 14 colours with dual-colour options (different inside and outside), giving 196 possible combinations. Solidor offers 27+ colours, also with dual-colour options — the widest range of any brand. Endurance offers around 19 colours. All three brands allow you to choose different colours for the door and the frame. For a full breakdown of Rockdoor’s colour options with RAL codes, see our Rockdoor colours guide.
