Chapter 15: Don & LowGateway 2: A new threshold for high-rise delivery
Don & Low’s Proshield provides a regulator-ready approach to airtightness
As higher-risk residential buildings move through the UK’s strengthened building safety regime, Gateway 2 has become a defining control point in project delivery. At this stage, the Building Safety Regulator assesses the full technical design before construction can begin. Approval now depends on clarity, evidence and consistency across every element of the building envelope.
For design teams, specifiers and contractors, this represents a structural shift. Performance claims are no longer enough. Products must demonstrate substrate-specific fire classification, repeatable installation methodology and clear documentation that supports the golden thread of information.
Within this context, airtightness is no longer a background technical consideration. It sits at the intersection of fire strategy, energy performance and long-term durability. Poor detailing, excessive interfaces or late-stage substitutions can undermine compliance and introduce avoidable risk at precisely the moment regulatory scrutiny is highest.
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In high-rise construction, airtightness contributes directly to thermal performance, condensation control and the stability of the wider facade strategy. Under the Gateway 2 regime, any ambiguity around materials, interfaces or substitutions introduces potential delay and design resubmission.
Membrane specification can no longer be treated as a minor package decision. It must be defined early, aligned with substrate conditions and supported by verified fire and performance data.
This is particularly relevant in modular and offsite environments, where repeatability and documentation are critical to programme certainty.
Gateway 2 has shifted the conversation from intent to evidence. Airtightness solutions must now be clear, repeatable and defensible at design approval stage.”
Don & Low’s Proshield has been developed specifically to simplify airtightness delivery in high-rise and modular construction while supporting regulatory transparency.
Proshield is a self-adhered, vapour-permeable airtight membrane designed for use on external walls and floors. It bonds directly to fibre cement, calcium silicate, OSB, timber, concrete, steel and other common construction substrates, without the need for primers, mechanical fixings or complex surface preparation.
By reducing installation stages and limiting interfaces, Proshield helps minimise workmanship variability. Whether applied in a factory-controlled environment or on site, the detailing approach remains consistent and repeatable.
Under increased regulatory oversight, fire classification must be explicit. Proshield has been independently tested in accordance with BS EN 13501-1 and achieves a Class B-s1,d0 reaction to fire classification when applied to a fibre cement board substrate. When applied free-hanging or on alternative substrates, a lower fire classification applies.
This clarity supports informed, defensible specification decisions in high-rise applications. Designers are able to align membrane selection with confirmed substrate conditions rather than relying on generic or assumed classifications.
As buildings become more airtight, moisture management becomes increasingly critical. Proshield combines airtightness with vapour permeability, allowing moisture vapour to escape while preventing uncontrolled air leakage.
The membrane meets Class W1 water resistance under EN 13859-1, providing temporary protection during construction phases when tall buildings may remain exposed to the elements.
This dual performance supports long-term durability while reducing the risk of interstitial condensation within high-performance facades.
Reducing interfaces reduces risk. In high-rise construction, airtightness must be designed as a system, not assembled as an afterthought.”
Gateway 2 places strong emphasis on information management and traceability. Proshield supports these requirements through:
A clearly defined, single membrane specification for walls and floors
Substrate-specific fire classification
Repeatable installation methodology
A complete range of compatible tapes and pre-formed corners
Consistent, documented performance data
By approaching airtightness as a system rather than a collection of components, designers and contractors can demonstrate intent more clearly and reduce uncertainty during regulatory review.
Clear, auditable specification A single defined membrane solution reduces ambiguity at design approval stage.
Substrate-specific fire performance Class B-s1,d0 when applied to fibre cement board, with clear classification on alternative substrates.
Independently certified by KIWA Provides the client with reassurance that the product claims and specifications are repeatable and accurate.
Reduced interfaces, reduced risk Self-adhered installation removes primers and mechanical fixings.
Moisture control without compromise Vapour-permeable performance supports condensation management.
Golden thread ready Repeatable detailing and consistent documentation support regulatory scrutiny.
Manufactured in the UK by Don & Low, Proshield benefits from in-house production and quality control. This ensures alignment between tested performance and product supplied to site. The membrane contains 20% or more recycled content, and an Environmental Product Declaration is currently in preparation, supporting transparent sustainability reporting as environmental requirements continue to evolve.
With over 230 years of manufacturing heritage, Don & Low continues to position performance verification and production control at the centre of product development.
Download ProShield's Technical Datasheet
The strengthened regulatory framework has changed the nature of high-rise delivery. Airtightness can no longer rely on best practice alone. It must be demonstrable, traceable and aligned with defined substrate and fire performance data.
In an environment where Gateway 2 requires evidence before construction begins, Proshield® provides a regulator-ready approach to airtightness without introducing additional complexity or ambiguity.
For high-rise and modular projects seeking clarity at design approval stage, certainty in the detail is no longer optional. It is essential.
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