November 26, 2013

The INTESANA Primer: The DER Solution

The INTESANA membrane, manufactured by Pro Clima of Schwetzingen Germany, is the state-of-the-art ingredient for Deep Energy Retrofit (DER) interior vapor control and air-tightness in cold and mixed climates. It is an intelligent membrane that changes permeability from 0.17 perms in winter weather to over 13 perms in summer, depending on the relative humidity around it. This intelligent range of permeability can give assemblies maximum protection against moisture damage.

Drying Capacity > Moisture Stress = Freedom from Damage

INTESANA is a WRB version of INTELLO, making it simultaneously waterproof and UV resistant. INTESANA is the perfect material to wrap your building, protecting the occupied interior from the weather, while outboard framing and insulation is being completed.



  1. When doing a DER where Code requires a Class II vapor retarder inboard:  INTESANA provides an interior Class II vapor retarder and interior airtight layer.
  2. When doing a DER where the assembly will have significant vapor retarding or vapor closed outboard layers:  In assemblies that have limited outward drying potential. For instance vapor closed roofs (flat or asphalt shingles), foam insulation boards or exterior sheathing (OSB, plywood).
  3. Batt insulation installations:  INTESANA provides double-duty of providing airtightness (eliminating worries of convective currents) and managing moisture in all seasons, which avoids vapor condensation problems.
  4. When interior air tightness is desired:  INTESANA provides a continuous, visibly verifiable and repairable interior airtight membrane in addition to vapor control.


Similar to natural materials like wood, INTESANA becomes more vapor open when exposed to higher relative humidity, and vapor closed in drier – winter – conditions.   The engineered membrane achieves a range of permeability and safety not possible with other vapor-retarders, vapor-barriers, or other materials.   And – crucially – as the moisture content rises around it above dangerous thresholds of approximately 70-80%, the membrane dramatically opens up to allow drying to prevent condensation and moisture related damages.

The chart below shows the vapor permeability curve.  We can see how INTESANA reacts as humidity levels reach dangerous levels – opening up radically to allow drying inward.

INTELLO vapor curve
INTESANA vapor curve


The membrane is not directional, so regardless of the direction it faces, it gives the same high performance. It responds to environmental conditions and becomes more vapor permeable due to rising relative humidity around it, causing vapor to move through it in the direction of lower vapor pressure. intesana before insulation

With this ability to promote drying, INTESANA can provide safety in even the most demanding circumstances. Below is one slide from an extensive Pro Clima study showing the relative drying ability of various vapor retarders.   Here is one of the worst case scenarios, where you have a north facing pitched roof at high altitude with a construction loaded with moisture at the outset – as construction often can be.   You can see that where the inboard OSB and plastic sheets are causing moisture problems, the intelligent vapor membrane INTESANA is driving down the moisture content to very safe levels.



02_intesana_070000-fixTHE APPLICATION OF INTESANA

INTESANA is part of a complete system of airsealing and vapor control that includes tapescaulking and gaskets – giving you robust and long-lasting airtightness.  (Note that INTESANA is to be installed over sheathing or with batt insulations.   It is not reinforced to support dense-pack insulations.)

Caleb Contracting - Cambridge, Vermont

Caleb Contracting – Cambridge, Vermont


In addition to the spec outline list below, we have a sample 3-part architectural construction specification for use and editing here.

  • Cover: Polypropylene
  • Membrane: Polyethylene-Copolymer
  • Protective layer/reinforcing: Polypropylene
  • Color: Green
  • Weight: 0.45 oz/sf (140 g/m2)
  • Thickness: 18 mils (0.45mm)
  • Perm rating: 13.20 to 0.17 (Sd value from 0.25m to >10m)
  • Tensile strength: 250 N/50 mm / 170N/50 mm
  • Elongation: 60%/60% (longt./transverse)
  • Tear resistance: 120 N/ 120N (longt./transverse)
  • Thermal conductivity: 0.85 hr.ft2°F/ (0.17 W/mK)
  • Long term temperature resistance: -40 F° to 196 F°
  • Water column: Over 8.2’ (2.5m) – DIN EN 20811
  • UV/weather exposure: Up to 2 months


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