The highly respected Federal Agency Deutsches Institut für Bautechnik (DIBt)* has certified INTELLO PLUS and DB+, per German testing standard DIN68800-2, for use in unvented assemblies with vapor closed exteriors. Such assemblies include unvented metal roofs, green roofs and gravel roof flat roofs, as well as vapor closed pitched roofs with asphalt shingles, EPDM, TPO etc. With this certification these materials are now officially building code compliant in Germany. As a result it is now possible to design and build assemblies in Germany with vapor closed exterior roofs without any additional sign-offs of local building officials. (The INTELLO certificate is here and the DB+ certificate is here.)
Our partner Pro Clima, the world leader in airtightness and vapor control, is the first and currently only manufacturer of smart vapor retarders (SVR) and airsealing membranes that has obtained official third party certification of its technical specification, material performance and compliance with the ruling DIN standard for wood construction.
The high quality of intelligent vapor variable membranes and airtightness have been proven to provide maximum protection against condensation, damage and mold – read the INTELLO Primer.
It’s About the Assembly Too
In this DIN 68800-2 standard the requirement for unvented roof assemblies has the following strict requirement:
Assemblies that are fully insulated between structural members and are vapor closed to the exterior are only allowed when the minimum requirements as defined in DIN 68800 part 2 exhibit A and DIBt protocols and include the following items:
- The airtight layer has to be on the interior/warm side – it explicitly cannot be on at the exterior (cold side) only.
- A vapor variable membrane is required on the warm side that has the follow:
- at 45% RH has an Sd-value >3.0m (below 1 perm)
- and at 70%RH has an Sd-value is between 1.5 and 2.5m (between 2.2 and 1.3 perms)
- The airtightness of the assembly must be tested
- Wood moisture content (M%) below 15% at installation
- Roof pitch 2° (> 3/8:12”), and no blockages of drains (for instance by leaves etc) or ponding
- No permanent shading of the roof (for instance of solar panels)
- No spaces below roof assembly that have prolonged high relative humidity
- Dark roof membrane (solar absorption of 80%)^
- Insulation to be installed should comply with:
- mineral wool per DIN EN 13162
- woodfiber per DIN EN 13171
- another insulation material that has an applicable installation standard.
The points above assure that the inward diffusion in the warm season is sufficient for the assembly to provide sufficient drying reserves.
If these minimum requirements cannot be met, then evidence of moisture/condensation protection per DIN En 15026 should be provided.
What does this mean for the US and Canada?
- This third party certification gives greater assurance to practitioners everywhere as to the capabilities and possibilities of making challenging assemblies safe without foam.
- If you can successfully make a vented assembly, do so – it is even more safe. See our post.
- Consult with your local code official as to the acceptability of the proposed unvented assembly.
- Be careful to execute tested airtightness and other required constraints. In addition to above, for example, see The Ten Golden Rules for Foam-Free Flat Roofs
- Solar radiation in North America is general much higher than in Germany, except in the Pacific NW, consequently a lighter color roof membrane can provide the sufficient inward drying potential in such cold/mixed climate zones.
We are happy to help you.
* Per Wikipedia: Deutsches Institut für Bautechnik(DIBt) may be translated as German Institute for Civil Engineering; however, the institute officially does not approve of any translation of its name and wishes to be called only by its original German name. It is an agency of the German federal government and grants European technical approvals (ETA) for construction products and systems by virtue of the Construction Products Regulation(305/2011/EU) of 9. March 2011.
Related Blog Posts:
- INTELLO Plus Resource Library
- INTELLO Plus specifications
- The INTELLO Primer
- An Interior Air Barrier Does It Better
- Keeping Sheathing Dry in High-R Double-Stud Walls – a WUFI study
- Yes, Unvented Roof Assemblies Can Be Insulated With Fiberglass – A WUFI Post
- Importance of Vapor Intelligence (video)
- 475 Does WUFI®: Mold Potential and Historic Masonry Retrofits in Climate Zone 6 (Burlington, VT)