We undertook a research and product development study to assist our client, Dörken Systems (then Cosella-Dörken), in developing best practices for window rough opening preparation and window installation using their DELTA®-VENT SA membrane, DELTA®-FLASH, and other products.

The Project

Our team performed material compatibility and field exposure testing to ensure the compatibility of materials. We also developed several proven alternate window rough opening preparation details using Dörken’s products and RDH’s best practice window installation details.

Alternate configurations included flanged and non-flanged windows, pre-strip versus cut-out window openings, and use of the DELTA corner-reinforcing product. Each detail was assembled by a contractor and video documented prior to installing windows and conducting air and watertightness testing at RDH’s window testing facility. Upon successful completion of the tests, our team drew each detail in 3D and produced guides to show step-by-step detailing.

The Result

We produced a set of videos and two builder guides for Dörken Systems and provided hands-on training to Dörken’s technical and sales staff.



May 6, 2019


Dörken Systems

Year Published:


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Key Services

Knowledge Sharing

Research at RDH Building Science Laboratories (RDH-BSL) is wide-ranging—from R&D projects that help manufacturers with product development to major research programs that help government and industry partners answer fundamental questions or address large-scale issues. Each project is approached as a unique challenge, requiring a tailored solution.

We undertake these projects in our two laboratory facilities and at field research sites in multiple climate zones across North America. Our staff includes highly trained and experienced researchers and technicians who understand the behaviour of assemblies, components, and materials, as well as the construction and design-related issues that impact performance.

In addition to laboratory and field research, computer-based modeling is an indispensable tool. We analyze and extend measured results using various modeling programs, including two- and three-dimensional heat flow programs (THERM, HEAT 3D), hygrothermal modeling software (WUFI Pro and WUFI Plus), and other in-house proprietary software. Many projects include several phases to allow validation of modeled results with measured data.

Graham Finch | Dipl.T., M.A.Sc., P.Eng.

Principal, Senior Building Science Specialist
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James Bourget | ABET, RRO®, CPHT

Principal, Construction Specialist
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Dave Ricketts | M.Sc., P.Eng., FEC

Founder, Senior Principal, Senior Building Science Specialist
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Conventional Roofing Study

In conventional low-slope roof assemblies, also known as exposed-membrane roof assemblies, the membrane is on the exterior of the roof insulation and structure, exposing it to exterior conditions including temperature, solar heat gains, night sky cooling, abrasion, and dirt.

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RDH Building Science