March 14, 2017 MGI with INTELLO double stud fiberglass

New Mold Growth Index and Safe Double-Stud Walls: WUFI Pro Shows INTELLO Plus is Key

Double-stud walls have been regarded as a simple to build, low-cost, high-performance solution since the energy crisis in the 1970’s.  (See our blog post The Double-Stud Wall Simplified: Low-Cost High Performance, and free CAD details)  Pack them right, meaning 3.8 to 4.2 lbs/cubic foot of cellulose, 2.5 lbs/cf for fiberglass or wood fiber – and as Jesse Thompson of Kaplan […]

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February 14, 2017 airtight gap

Top Ten *NO* Eleven Air Barrier Failures

1. It’s not continuous! The mother of all failures. You don’t have an air barrier if it’s not continuous – it won’t be air tight. Many of the items that follow below are all causes of discontinuity. Like a balloon or a submarine – the continuity of the airtight layer must be sacrosanct. While discontinuity can […]

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January 23, 2017 Vana_Moving

How to Stay Airtight When Buildings Move

Buildings move. Ensuring that your air barrier is resilient to movement is crucial to ensuring the longevity and performance of your building. Unless you’re building a structure using just one material (like superadobe), your building will consist of an array of different materials. In response to fluctuations in temperature and humidity, different materials expand and contract at […]

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November 22, 2016 crashtestdummy

Drive Safe, Build Safe

As we get ready to drive over the Thanksgiving and Christmas breaks, our minds turn to safety and the risks we take for granted every day.  What’s your risk tolerance? When you drive, do you tailgate the car in front of you or do you leave a safety buffer?  Although you are very unlikely to […]

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October 12, 2016 bainbridge-havelock-wool-thumb

Havelock Sheeps’ Wool and Performance Insulation

Insulation  contractors are on the front lines of high performance building, delivering comfort and efficiency.  It’s a tough business. It’s rough to manage high turnover, squeezed margins, and communication barriers.  Those who take pride in the work, are interested in the results.  And leaders do the best with what they have, while also continuously looking for […]

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October 3, 2016

New Yorkers, Start Your Blower Doors: It’s Blower Door Day

We’re happy to proclaim October 3rd Blower Door Day – here at our headquarters, in Brooklyn, New York – as the new residential building energy code requiring blower door testing at 3ACH50 comes into effect.  As we noted in May, of course New York isn’t the first to adopt the 2015 International Energy Conservation Code and keep […]

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September 9, 2016 ridge-vent

Vapor Venting An Unvented Roof: In Praise of Belts and Suspenders

Planes can fly safely with one engine. And you can keep your pants up with just a belt. But if you’re looking to be protected from fools, then adding suspenders to the belt might be what sets you free. So while we’ve previously outlined the essential importance of inboard airtightness and vapor control and have specifically written […]

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September 2, 2016 jeff_g_diagram

Cambridge MA – Small Urban 2-Story Gets a High Performance Upgrade

Here’s a sweet example of a successful Deep Energy Retrofit (DER) with airtight, foam-free walls and high performance ductless ventilation. The designer and GC is Jeff Geisinger, a Boston-based architect who recently completed a SMArchS in Building Technology at MIT. Peruse the stunning before-and-after photos along with Jeff’s great diagrams here (click on large photo for full-screen slide show). Airtightness Before Insulation With a recently […]

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August 16, 2016 swinburn_headline

The Dream Project: High Performance, Right-Sized, Thoughtfully Detailed

If you haven’t heard of Robert Swinburne Architect or Bluetime Collaborative yet, do yourself a favor and check out his website and blog. If you have followed his career, you know that he’s a talented and thoughtful architect focusing on single family homes in the Brattleboro, VT area. He is also a Certified Passive House Consultant (CPHC). One of Bob’s […]

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July 8, 2016 MelpetThumb

Healthy Indoor Air Quality Confirmed With LUNOS e²: Monitoring Shows HRV Does The Job At Melpet Farm

The residences at Melpet Farm is an affordable housing development by Preservation of Affordable Housing, Inc (POAH). Their mission is to create, preserve and sustain affordable and healthy housing communities that provide economic security and access to opportunity for all people. At Melpet, apartments were designed for low-energy use in townhouse buildings that incorporated airtight and highly insulated envelopes combined with hybrid LUNOS e² […]

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June 29, 2016 Large-back-wall

Blowerdoor Testing The Best Doggie Door In North America

We’re excited to put the super-efficient Freedom Pet Pass doggie door to the test. In this quick edit of the video, we introduce it by showing how the double-layer of magnetic strips work to hold the insulated flap in place while easily allowing for opening with the push of a big wet nose. These doors come in […]

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May 27, 2016 BlogThumb

How To Prepare For High Performance Windows

Windows might make you nervous. They’re often big and heavy, yet fragile. And in a high performance building, windows are the most expensive components. But that investment in great windows has a big payoff as well. High performance windows deliver on interior comfort and building efficiency – so you don’t have to rely on energy-sucking HVAC systems […]

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May 23, 2016 double_stud

The Double-Stud Wall Simplified: Low Cost, High Performance

Simplify. We know pushing standard code-minimum construction toward high performance is complicated. So we’re always looking for ways to simplify – to simultaneously reduce cost while optimizing efficiency and occupant comfort. [See our recent post on Breaking The “Upfront Cost Barrier”.] The double-stud wall is a well established method for creating a very economical, durable and […]

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May 16, 2016 Blowerdoor_test

New York State Mandates Blowerdoor Testing Beginning October: Our Reaction

Airtightness is for Everyone As a company built on airtightness, we have always pushed the building industry and building codes toward progressively tighter and tighter building goals. Because even at “just” 3.0ACH50, increasing the airtightness of the building envelope will make a huge difference for the comfort and the energy efficiency of projects built to current code. […]

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May 5, 2016 EnergyLoss

Ventilation’s Energy Problem: Most Of It Just Sucks

Inaugural post of the Turning BS into Building Science series by Lucas Johnson Most often, ventilation sucks. When I was the third contractor enrolled in Energy Upgrade CA, I enjoyed being on the cutting edge of high performance building. However, ventilation was repeatedly one of the biggest challenges we faced as a state trying to push for affordable […]

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March 31, 2016 asphalt roof

The 8 Golden Rules for Foam-Free Unvented Asphalt Shingled Roofs

When insulating a wood roof structure, 475’s goal, as always, is to build in the most healthy, structurally sound and ecologically friendly way – thereby achieving truly high performance.  This means we generally try to avoid using foam above or below the roof deck (see our 475 series Foam Fails). With foam out of the equation, we […]

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January 8, 2016 explosion

Make Better Choices: Toward A Less Toxic World

Nature is toxic enough – it would seem sensible that we try to limit the amount of toxicity industry contributes.  Almost nothing is completely good.  But in the building industry as with much of modern life there are a dizzying array of invented chemical compounds that may provide great benefits but also deliver varying degrees of […]

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January 4, 2016 Screen Shot 2016-01-04 at 10.27.23 AM

5 Takeaways from the Building Science Corp Thermal Metric Study

The Building Science Corporation completed ground breaking research in 2015 – with an updated Thermal Metric Summary Report issued last June. Here’s our take on it: 1.  It’s an Amazingly Useful Tool In the executive summary BSC notes:  “Contemporary insulation materials and systems are more or less sensitive to thermal bridging, workmanship (i.e. quality of installation), internal convection […]

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December 3, 2015 trapped

Insulating Unvented Roof Assemblies: Foam Free

We’re big fans of Fine Homebuilding.  In the most recent issue of Fine Homebuilding, Martin Holladay wrote a piece on Insulating Unvented Roof Assemblies.  We agree that avoiding sheathing rot is critical, and that air permeable insulation such as fiberglass or cellulose cannot be used alone.  But in it, unfortunately, all four options provided are dominated […]

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August 3, 2015 2xEbookipad-300x200

New 475 eBook: High Performance 2x Framing

This free details guide is the third in the 475 ebook series 2x wood frame construction is very common and typically provides poor performance. This free ebook illustrates how we can transform the 2x approach into a high-performance enclosure that affordably delivers the highest levels of comfort, energy efficiency and longevity. Airtightness disproportionately effects enclosure […]

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July 30, 2015 ServiceCavity

The Service Cavity – Making Airtight Construction Easy

We know that the importance of airtightness is second only to keeping the rain out.  This is because airtightness greatly effects indoor air quality, thermal comfort, and energy efficiency – while protecting the enclosure from moisture damage (see here).  Given these pretty convincing reasons, what should our airtightness target be, and how does a service cavity help […]

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July 28, 2015 NY Times Building Entry

Metered New York: Making Building Energy Data Useful

In 2009 New York City instituted mandatory energy use reporting for all buildings over 50,000 sf – initiating a potential windfall of useful information to better understand what our big buildings are actually doing. And if we could understand what is actually being consumed we’d have a better shot at making substantial performance improvements.   While compliance […]

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July 14, 2015 IntellovsOSBvsPlywood2

Why The Vapor Curve Matters

How vapor variable materials stack up when it comes to mileage and protection Intelligent membranes, or smart vapor retarders, can help prevent condensation in enclosure assemblies (walls and roofs) in winter, while allowing inward diffusion in summer. This transformation is important to assure the safety of an insulated assembly, by increasing its drying reserves so it can cope with (unforeseen) moisture — both into […]

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May 28, 2015 BrickTest

475 On-Site: Karsten Tube Testing of Masonry Walls

On a recent visit to Jane Sanders’ EnerPHit Brooklyn brownstone retrofit, Floris took the opportunity to demonstrate the basics of Karsten tube testing. These tests are one of the ways to ensure the brick is good and ready for a high performance retrofit. Passing the test proves the brick is not too absorptive from wetting […]

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January 5, 2015 PoppingTheBalloon

BSC & PHIUS Passive Building Report Not Airtight

Very good enclosure airtightness is a cornerstone characteristic of low-energy, resilient, high-performance (Passive House) buildings. Air control is so important that the Building Science Corporation ranks it second only to keeping the rain out – one notch above vapor control and two notches above thermal insulation – in making a functional enclosure.[1] The Passive House […]

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December 5, 2014 Gutex_Pallet

Alford, MA: GUTEX Roof Makes Sustainable High Performance

We’ve blogged about the many benefits of GUTEX wood fiberboard insulation for truly green construction – see this video introduction and our GUTEX primer. To begin with, it’s one of the most sustainable insulation products, created from wood scraps and manufactured with a super efficient dry process for minimal environmental impact. It is also very practical, delivering continuous insulation and weather protection in […]

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October 8, 2014 Foam-up-close-200x200

Foam Fails Reason #5: Excessive Shrinkage

With the growing use of foam plastic insulation in building construction, first in commercial roofing and then too often metastasizing over the entire building enclosure, it is being used increasingly as an air barrier component. This is a problem for many reasons – see Foam Fails – and one of them is excessive shrinkage. Essential to maintaining airtightness is maintaining […]

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