02 — DESIGN CHALLENGE

A relatively small roof with unusually complex geometry

The size of the extension understated the technical demands of the roof.

Large glazed openings, multiple roof planes and narrow drainage channels created numerous junctions where the roof covering, insulation, gutters and vertical cladding had to be considered together.

The initial construction drawings proposed a combination of zinc and single-ply membrane. During site discussions with the building contractor and architect, the detailing was simplified and rationalised to reduce unnecessary material interfaces.

03 — MATERIAL STRATEGY

Zinc for architecture. Stainless steel for drainage.

Standing-seam zinc was retained as the primary visible roofing and cladding material because of its architectural appearance and suitability for the geometry of the extension.

Terne-coated stainless steel was introduced to the internal gutter channels where greater robustness, larger tray dimensions and fully soldered outlet detailing were advantageous.

Using each material according to its strengths produced a cleaner and more resilient solution than forcing a single material across every part of the roof.

07 — MATERIAL INTERFACES

Detailing zinc against stainless steel

Combining two sheet-metal roofing materials requires careful consideration at every junction.

The interfaces were configured so that water moved naturally from the zinc roof planes into the stainless-steel drainage channels without relying on vulnerable reverse laps or unnecessarily complicated joints.

Adequate upstand heights and mechanical separation were maintained at adjoining interfaces.

08 — SOLDERED DETAILS

Where fabrication becomes roofing

Several details could not be achieved using proprietary components and were therefore formed specifically for the project.

These included soldered zinc junctions, stainless-steel outlets, spigots, overflows and transitions around restricted roof geometry.

This type of project demonstrates the overlap between roofing, sheet-metal fabrication and architectural detailing.

10 — THERMAL PERFORMANCE

A continuous insulated roof envelope

The warm-roof arrangement placed insulation above the structural deck, maintaining a more continuous thermal layer across the roof.

This reduced thermal bridging through the timber structure and avoided reliance on a ventilated void beneath the metal covering.

11 — ACOUSTIC CONSIDERATION

Considering the space beneath the metal roof

The extension was intended for use as a pottery studio, meaning the internal environment was an important part of the roof design.

The layered roof construction, insulation and separation beneath the finished zinc helped reduce the transmission of impact noise from rainfall into the occupied space below.

13 — TECHNICAL KNOWLEDGE

Metal roofing is determined by the detail beneath it

The performance of zinc roofing depends on far more than the visible sheet metal.

Substrate design, vapour control, insulation continuity, separation layers, tray dimensions, fixing zones, thermal movement and drainage geometry all influence the long-term performance of the completed covering.

Metal Roofing Guidance →
Zinc Roofing →
Stainless-Steel Roofing →
Roofing Regulations + Standards →

14 — INDEPENDENT CONSULTANCY

Design review for complex roof interfaces

Architectural metal roofing frequently requires careful review of substrate construction, drainage, condensation risk and interfaces before fabrication begins.

Strut Building Surveyors provides independent roof-condition surveys, building-envelope consultancy, defect investigation, repair specifications and project oversight.

The consultancy operates independently from Neal Roofing where clients require professional advice separate from the contracting function.

Strut Building Surveyors →