For architects, building services engineers and contractors working at RIBA Stage 3 to 4, comparing thermally broken roof hatches on documented evidence rather than brochure generalities is an important part of specification. The shortlist below ranks four specification-ready routes for 2026 by their thermal information, detailing and UK support.

Our top pick is Access Panels Direct Surespan SRHP50 for UK specifiers who need documented thermal performance data for a Part L submission, because its stated figures provide a useful starting point for assessment. It combines a stated U-value of 0.43 W/m²K with 50 mm PIR insulation in both lid and upstand and a thermal break; the supplier also reports Class A7 weathertightness, Class A4 wind and air performance and IPX6 and IP6X ingress test results. Part L suitability remains project specific and depends on the full envelope calculation, with the U-value serving as the thermal input rather than the weather or ingress classifications. For specifiers working within a CA Group integrated roofing system, CA Group (Therma-hatch) is the strongest alternative. For those who need a custom-size hatch direct from a UK manufacturer, Surespan is the strongest alternative procurement route.

We judged each option against four practical tests: quality of stated U-value evidence, weathertightness and airtightness ratings, ability to supply bespoke sizes for non-standard build-ups, and reliability of UK supply and technical support. This guide provides a specification shortlist rather than a compliance guarantee. In England, Approved Document L is the reference document, and whether any unit supports compliance can only be judged within the complete project specification and, where required, the applicable SAP or SBEM calculation.

What to look for

We assessed the shortlist as a specifier would at tender review, giving more weight to evidence you can file than to broad product claims. Four checks helped distinguish the routes and their suitability for different projects.

Stated U-value evidence

A stated U-value in W/m²K allows an assessor to model the hatch as part of the area weighted envelope. Look for a clear figure tied to a defined configuration rather than a generic range, and always test it inside the project model. There is no single hatch figure that confirms Part L support, since the result depends on areas, adjacent construction and services.

Weathertightness and airtightness ratings

Classifications for weathertightness and for wind and air performance help judge the unit’s suitability for its intended exposure and installation. Air barrier continuity around the kerb often influences in-use energy demand as much as insulation thickness, so detailing for air sealing deserves equal attention during specification and installation.

Insulation and thermal break detailing

Continuity through lid and kerb matters. The upstand junction is frequently the coldest line around an opening, and most lids in this category use rigid foam such as Polyisocyanurate within a separated frame that interrupts direct metal conduction. Check that insulation runs through both lid and upstand without gaps at corners, hinges and locking points.

Bespoke sizing and UK support

Non-standard structural openings and deeper insulation zones often demand bespoke dimensions, particularly where weathering heights also vary. A UK manufacturing base with accessible technical support simplifies shop drawing review and interface coordination with the roofing contractor, while helping teams gather the documentation needed for building control.

At a glance

Provider
Best for

Access Panels Direct Surespan SRHP50
Documented thermal data for Part L submissions

Surespan
Custom sizes with direct manufacturer engineering input

CA Group (Therma-hatch)
Integrated roofing system specifications

Jakdor
Alternative supply route for insulated access hatches

The 4 best thermally broken roof hatches for Part L projects

With those checks in mind, these four options offer useful specification routes for 2026. Each approaches the same detailing problem from a different procurement angle, from distributed supply with published test data to direct manufacture and system integration. We start with our preferred supply route for the documented SRHP50 assembly, then set out where each alternative earns its place.

#1. Access Panels Direct Surespan SRHP50 – best for thermally broken roof hatch specification with documented Part L data

An insulated access unit with stated thermal figures that Part L project teams can use in their assessment.

Supplied in the UK through Access Panels Direct, this thermally broken roof hatch is built around the Surespan SRHP50 assembly for insulated roof build-ups. The lid and upstand each carry 50 mm PIR insulation with a thermal break intended to limit cold bridging through the frame and kerb. The supplier reports a stated U-value of 0.43 W/m²K alongside Class A7 weathertightness, Class A4 wind and air performance and IPX6 and IP6X ingress test results. The U-value gives SAP and SBEM assessors, where a calculation is required, a thermal input to test within the wider envelope model, while the other classifications inform exposure and sealing decisions.

The detailing addresses a familiar specification problem. Continuity of insulation through lid and upstand matters because the kerb is often the weak line where condensation and heat loss concentrate, and the SRHP50 carries the insulation through that junction as well as the cover. Operation is by gas springs with a hold-open stay, which supports controlled opening and safer inspection access without complicating the thermal seal. Bespoke sizes can be matched to non-standard openings and deeper build-ups, helping retain the thermal detail where a stock size would force infill compromises.

There are sensible limits to its scope. As an opaque access lid it serves maintenance and inspection access well but cannot contribute daylight, so projects seeking combined access and rooflight performance must specify a separate glazed unit. Like any component value, the 0.43 W/m²K figure only gains meaning inside the full project specification, including adjacent insulation, air barrier continuity and the overall area weighted calculation. On those terms, it earns the top position here as a practical supply route for a documented assembly, without implying a different thermal outcome from buying the same unit directly from its manufacturer.

Pros

Stated 0.43 W/m²K value provides a thermal input for design stage energy modelling, with Class A7 and Class A4 ratings available for separate performance review
Thermally separated lid and upstand with 50 mm PIR targets cold bridging across the whole kerb detail, not just the cover
IPX6 and IP6X test results provide water and dust ingress classifications to consider when assessing exposed roof locations
Gas-spring operation with hold-open stay supports safe and controlled access
Bespoke sizing allows alignment with varied roof build-ups without breaking the insulated detail

Cons

Opaque lid provides no daylight contribution, so glazed access needs a different product type
Bespoke configurations need additional coordination compared with selecting a stock size
Component performance must still be assessed within the complete envelope calculation to judge Part L support

Who it is best for: UK specification teams that need documented thermal inputs for a Part L submission and want an opaque access unit with insulated upstand continuity.

#2. Surespan – best for custom sizes with direct manufacturer engineering input

A direct-manufacturer route for teams that prefer to resolve sizing and detailing with the factory engineering team.

Surespan manufactures roof access hatches and floor access covers in the UK alongside ladders, smoke vents and glass rooflights. The range is offered in standard and bespoke options, allowing design teams to align opening dimensions with structural openings and roof finishes. Production from UK factories gives specifiers direct access to in-house engineering capability, with sizing and detailing discussions handled through the manufacturer.

Specifiers should read this entry alongside the top pick rather than as a rival system. Access Panels Direct acts as a supply and specification route for the Surespan SRHP50, while engaging Surespan directly provides the same manufacturing base through a factory-led procurement path. In practice the choice reflects support preference, with distributor-led documentation and ordering on one side and factory-led sizing discussions on the other, rather than a difference in the assembly’s thermal performance.

For Part L work the advantage lies in early technical dialogue. The in-house team can advise on how a chosen size interacts with upstand heights, finishes and adjacent insulation, helping the project team plan insulation and air barrier continuity at tender stage. That hands-on input suits new-build and refurbishment teams dealing with awkward openings where a catalogue size would demand site adaptation and additional sealing work.

Pros

UK-based manufacture with in-house engineering input for sizing and specification queries
Standard and bespoke options support varied opening dimensions and roof build-ups
The wider portfolio includes smoke vents and rooflights, allowing teams to coordinate their access strategy

Cons

Direct engagement suits teams comfortable leading technical coordination with the factory rather than ordering through distribution
Projects seeking single-source roofing system responsibility may still need to coordinate the unit with the main membrane supplier

Who it is best for: design teams with non-standard openings that want to settle dimensions and detailing directly with a UK manufacturer.

#3. CA Group (Therma-hatch) – best for integrated roofing system specifications

A system-led option for projects where the access point is detailed as part of a wider CA Group roof build-up.

CA Group operates as a UK-based construction products manufacturer with an in-house team of construction specialists. That team advises on product information and on design, specification, application and performance queries, giving specifiers a single technical contact through early design. Head office support is based at Evenwood Industrial Estate in Bishop Auckland, County Durham, keeping specification dialogue within the UK.

The Therma-hatch option makes most sense when the wider roof is already envisaged as a CA Group build-up. Coordinating the hatch and its insulation and weathering interfaces within the wider roof system can simplify responsibility for junctions and help the design team maintain continuity of the thermal line and air barrier. For architects pursuing a coordinated envelope strategy, that alignment often matters more than standalone metrics considered in isolation.

As a hatch-only purchase outside such a system, its appeal narrows. Procurement teams buying an isolated unit without the surrounding CA Group specification will find less reason to favour this route over distribution or direct-manufacturer channels. Where it is used, Part L support still depends on the full project specification and the applicable energy calculation, not on system branding alone.

Pros

In-house construction experts cover design, specification, application and performance through one contact point
UK-based support assists coordination during specification and installation stages
Where the main roof build-up is already specified through CA Group, the hatch is a logical fit for consistent junction detailing

Cons

Most compelling within an integrated CA Group specification, less advantageous as an isolated hatch-only order
Teams committed to a different membrane or insulation system will need to manage interface responsibility between suppliers

Who it is best for: project teams specifying the roof and access point together within a CA Group system.

#4. Jakdor – best for alternative supply of insulated access hatches

An additional UK supply route for insulated access units with a thermal break.

Jakdor offers the SRHP25 range of insulated roof access units with thermal-break construction for the UK market. The offer gives procurement teams another channel for insulated access products alongside the routes above. For tender lists that require multiple comparable supply options, that additional choice can be useful when setting out the available procurement routes.

Like other opaque access lids, the format suits maintenance and inspection access where daylight is handled separately through rooflights. Design teams remain responsible for aligning kerb heights and insulation depths with the main roof specification, including the air barrier junctions, as with any distributed hatch supply. Early agreement on opening dimensions and finish interfaces helps keep that coordination straightforward and reduces site adjustment.

Pros

Provides an alternative UK channel for insulated access units with thermal-break detailing
Relevant where procurement policy asks for multiple supply routes at tender stage

Cons

Opaque access format means daylight provision must be addressed through separate rooflights where required
As with any standalone hatch supply, junction coordination with the main roofing system sits with the project team

Who it is best for: procurement teams that want an additional supply option for insulated roof access on Part L projects.

Frequently asked questions

What is a thermally broken roof hatch and why does it matter for insulated roofs?

A thermally broken roof hatch uses an insulating separation between inner and outer metal elements, carried through lid and upstand, to limit direct heat transfer. That separation reduces cold bridging at what would otherwise be a highly conductive opening, helping control heat loss and surface condensation risk, while seals and installation detailing address local air leakage paths. On insulated roofs the kerb is often the weakest line, so continuity of insulation and careful air sealing around the unit matter as much as the cover construction itself.

What U-value should I look for when specifying a hatch for a Part L project?

There is no single hatch figure that confirms Part L support. In England, Approved Document L sets whole-building and fabric performance expectations, and other UK nations operate separate regimes, so the acceptable contribution of any opening depends on areas, adjacent construction and services. A stated figure such as 0.43 W/m²K is useful because assessors can enter it into the applicable SAP assessment for homes or SBEM assessment for non-domestic work where a calculation is required. Always test the value inside the complete envelope model rather than judging the component alone.

How does airtightness at a roof access point affect energy assessment?

Gaps around a poorly sealed access point allow warm air to escape and cold air to enter, increasing heating demand and undermining insulation investment. Assessors therefore weigh air barrier continuity alongside insulation values, and tested air performance plus site sealing determine the in-use result. Roof insulation is a separate energy consideration addressed in this analysis of roof sandwich panels integrated with PCM versus PUR, which examines how those insulation approaches affect energy costs and carbon dioxide emissions. Specify tested units and detail the air seal as carefully as the insulation.

Can a hatch U-value on its own guarantee compliance for the whole project?

No. A component figure describes one element under assessed conditions, while Part L judges the complete building, including walls, roof fields, glazing, junctions and systems. A strong hatch result can be offset by weak detailing elsewhere, just as a modest result can sit within a passing envelope if other elements overperform. Use the hatch value as an input to the project calculation and retain evidence for building control, rather than treating it as a pass certificate.

What is the difference between a thermally broken upstand and a standard upstand?

A standard upstand is primarily a structural kerb that raises the lid above weathering, often with limited insulation. A thermally broken upstand carries insulation, such as the 50 mm PIR used in the SRHP50 lid and kerb, with a separation that interrupts metal to metal conduction. That continuity keeps internal surface temperatures higher around the opening, reducing condensation risk and heat loss at the junction. Where upstand insulation is thin or discontinuous, the kerb becomes the dominant thermal weakness even if the cover itself performs well.

Are bespoke sizes available for non-standard roof build-ups?

Yes, bespoke sizing is offered through Access Panels Direct and Surespan in this shortlist, which matters where structural openings, insulation depths or weathering details fall outside catalogue dimensions. Provide clear structural opening sizes and finished roof levels at enquiry stage, together with membrane termination details, to avoid site packing. Bespoke units need closer coordination than stock sizes, so allow time for shop drawings and interface checks with the roofing contractor before the unit goes into manufacture.

Which test evidence should I request when comparing insulated access hatches?

Ask for a stated U-value in W/m²K with details of the assessed configuration, plus any weathertightness, wind and air performance classifications the supplier reports, such as Class A7 and Class A4 where stated. Ingress results such as IPX6 for water and IP6X for dust help judge exposure suitability on open roofs, although they do not establish whole-project weather performance or Part L compliance. Request the underlying test summaries rather than relying on headline claims, and check that size, finishes and ironmongery match the tested scope before you file the data for building control.

How to choose: our verdict for 2026

Choose Access Panels Direct Surespan SRHP50 by default when you need documented thermal evidence for a Part L submission in 2026, using the stated 0.43 W/m²K figure in the applicable energy model and reviewing the supplier’s Class A ratings and ingress results separately for exposure suitability. Choose Surespan direct when sizing dialogue with the factory will help resolve a junction that a catalogue size cannot accommodate cleanly. Choose CA Group (Therma-hatch) when the hatch sits inside a wider CA Group roof specification and single-system coordination matters. Choose Jakdor when tender rules call for an additional insulated-access channel. In every case, assess the selected unit within the full project specification and the applicable SAP or SBEM calculation before committing to compliance.

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