smart wall


Archigram’s A Walking City, 1964: boundless energy & engineering anyone?

For thousands of years buildings were made with a keen regard for nature and historically building science was intimately attuned to natural phenomenon.  Then, the 20th century builders, with giant resources of energy and rapid scientific advancements tried to conquer the vagaries of nature.  Natural solutions were ignored and flaunted – they made up, down, and down, up – if they felt like it.  And any unintended bad consequences would be answered with yet more engineering and power.  It has been brute force all the way down – landing us in a dystopian landscape.   Today our traditional buildings are so chemical and energy dependent, they are a leading cause of our environmental catastrophe. Their resulting pollution has acidified the oceans and warmed the climate to such an extent that we imminently face massive species die-offs.  And we’re poisoning everything – all species, ourselves and our families – in the process.  Soon there will be more plastic than fish in the oceans!

Our poster child of industry run-amok is spray foam insulation. We’ve written about many of the problems in our Foam Fails series.  Spray foam is the cornerstone of building enclosure failure. Fortunately there is growing industry understanding that spray foam is an unreliable, toxic, and expensive approach which is based more on Madison Avenue marketing than common sense. We say: Less is Best.


The answer to our predicament today, is not to throw off technology and return to the Primative Hut, but instead, is to synthesize our understanding of natural systems, and selectively use technology that provides great benefits with manageable environmental impacts.

 smart wall

Lloyd Alter, writing in Treehugger, notes that our current obsession with energy efficiency and high-performance, as realized in the Passive House Standard, is not enough.  Yes, efficiency and comfort are critical to our sustainable future, but to ignore other critical factors may likely result in just another techno trap.    Lloyd proposed “The Elrond Standard” – in reference to Elrond Burrell’s formulation that eco-friendly building must, in addition to reaching Passive House performance, also be: made of materials that are non-toxic and of low embodied energy; and the building should be located in a walkable neighborhood.  We couldn’t agree more.

Focusing on what we do at 475 – providing critical knowledge and components for high performance enclosures and buildings – we know we can make smarter choices today.  The smarter choice we offer is what we call the Smart Enclosure.  The Smart Enclosure is an assembly system made of non-toxic materials, with low embodied energy, that creates long-lasting construction – and delivers comfort, health, and efficiency without rot, mold, or other maintenance and health headaches.


The Smart Enclosure is a return to fundamental principles of building science.  Then we leverage the basics of natural principles with highly selective technological innovation and manufacturing – working in harmony with nature, not in opposition.  The Smart Enclosure acknowledges its profound relationship with the outside environment and the occupants within.   This system is made of efficient, resilient and sustainable products, including HAVELOCK WOOL sheep’s wool insulation, Pro Clima membranes such as INTELLO Plus, and GUTEX exterior insulation board – resulting in buildings that are better for people and for the planet.

So what are key attributes of the Smart Enclosure assembly?

  • Natural Insulation Materials.  Continuous GUTEX Wood fiberboard insulation and HAVELOCK WOOL sheep’s wool cavity insulation insulation are non-toxic, zero-VOC high-performance materials.
  • Vapor Intelligence.  Pro Clima INTELLO Plus is a zero-VOC, vapor intelligent membrane that builds drying reserves by responding to changing conditions of vapor drive and moisture concentrations – and ensuring the long-term health of your building by preventing moisture loading of the building assembly.
  • Airtightness.  An airtight enclosure is essential – providing comfort, energy efficiency and protection against moisture damage – to high performance building.  Pro Clima membranes and tapes provide long-term building airtightness.
  • Comfort and Indoor Air Quality.  A vapor-intelligent, airtight assembly that utilizes natural materials can guarantee a high level of indoor air quality and occupant comfort. The Smart Wall resists mold growth, eliminates concerns about off-gassing and VOCs, and is very effective at sound attenuation – all contributing to a healthy and comfortable indoor environment.

The Smart Enclosure starts with a Smart Wall that embodies these qualities.   Let’s break the assembly down.


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Moving from interior to exterior, the Smart Wall consists of:

  • Interior finish
  • Furring strips forming a service cavity (with optional additional sheeps’ wool insulation) – for wiring, outlets and other services.
  • INTELLO Plus interior air barrier and vapor-intelligent membrane
  • Framing with HAVELOCK WOOL insulation,
  • Structural sheathing (from boards to exterior grade gypsum board)
  • Continuous GUTEX wood fiberboard exterior insulation and WRB
  • Furring strips for back-vented rainscreen.
  • Exterior siding rainscreen

smart wall

The Smart Wall is the ideal solution for low-carbon, high-performance wall construction.  Let’s break it down further.



Wool is just about as natural as an insulation material can get. Havelock Wool, from New Zealand sheep, is a durable, carbon-negative, all-natural, and very high performing form of insulation. Some of the benefits of wool insulation include:

smart wall

Havelock Wool is a safe, all-natural insulation material. It is also baby-tested and approved.

  • Havelock Wool is a safe, all-natural insulation material. It is also baby-tested and approved.Moisture Control.  Wool insulation is capable of absorbing up to 35% of its weight in moisture, and manages moisture levels against 65% relative humidity.
  • Toxin Sequestration.  Wool binds permanently to formadehyde, sulfur dioxide, and nitrogen oxides, sequestering them from the air that you breathe and improving the health of the indoor environment.
  • Chemical free.  No dyes, toxins, or other chemicals are added to this virgin, untreated wool product.
  • Fire Resistance.  Wool extinguishes after smoldering, limiting the spread of fire. This is in great contrast to the high flammability of petrochemical-based insulation materials.
  • Easy Installation. Wool is available in batts, or can be blown-in behind the interior air membrane like cellulose insulation.
  • Long-lasting Performance.  Wool resists mold growth, and won’t sag over time, meaning that your R-values and healthy indoor air quality will be maintained over the life of the wall assembly.
  • Zero-waste.  Wool can be reused or composted after use, mitigating concerns about the life-cycle impacts of building materials.

Havelock Wool comes in batt or loose-fill (not dense-pack). Wool is naturally a straight fiber, able to hold its form without settling. The wool targets 0.5 lbs/ft3 whereas cellulose dense-packed would be 3.5 – 4 lbs/ft3. Wool is a safe, comfortable, and natural alternative to synthetic insulation. So give your house the sweater it deserves with Havelock Wool.


smart wall

Guys at Kaplan Thompson enjoying working with GUTEX in Maine


GUTEX is an ideal product: exterior sheathing that serves as a WRB, a vapor-open, wind-tight layer, and additional building insulation. Some of the benefits of GUTEX include:

  • Vapor open and weather-resistant.  At 44 perms, GUTEX wood fiber boards are highly vapor-open, allowing outward drying and preventing moisture build-up in your wall assembly.
  • Noise attenuation.  GUTEX is dense, and provides additional noise attenuation to ensure occupant comfort.
  • High thermal lag.  Because of its density and high specific heat capacity, GUTEX boards heat up slowly. This keeps the building cool on hot days, and comfortable at night.
  • Net carbon sink. GUTEX is made from post-industrial recycled wood chips mixed with shavings of spruce and pine. Because trees take carbon from the atmosphere, GUTEX is a carbon-negative product.
  • Low impact dry production process. The unique dry-production process for GUTEX increases the density (and therefore performance) of the boards while reducing the energy required for their construction.
  • Environmentally friendly disposal.  GUTEX can be re-used at the end of their life in your building, can be burned as fuel, or, because they are biodegradable, will easily break down.

GUTEX wood fiber board serves numerous roles in your building assembly and ensures long-term building performance.


smart wall

The vapor variability of INTELLO Plus ensures the maximum drying potential of your wall assembly.


The vapor variability of INTELLO Plus ensures the maximum drying potential of your wall assembly.

Pro Clima membranes are the lynchpin of our approach to airtightness.  INTELLO Plus, our recommended interior membrane, ensures long-term airtightness and vapor intelligence. This vapor-variable membrane is responsive to interior relative humidity levels to ensure that moisture is able to leave the assembly.  As Alex Wilson has written on BuildingGreen, “Smart Vapor Retarders: Not Just Your Grandmother’s Poly“.


INTELLO Plus with service cavity

smart wall


INTELLO Plus with service cavity

Pro Clima membranes (and the tapes that complement them) are the best way to ensure permanent building airtightness without risking the accumulation of moisture that can lead to the growth of mold and rotting structural elements.


A sustainable future means re-balancing our respect for natural processes and our technological innovations.  We believe the Smart Wall, consisting of Pro Clima membranes, Havelock Wool insulation, and Gutex wood fiber board, exemplifies what is possible.   The Smart Enclosure can ensure long-lasting, high-performance buildings that are healthy for occupants – and for the planet.

So, make the Smart Wall choice.  Contact us to get started today.

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