Vapor Control in Walls with Continuous Insulation-IRC Chapter 7 vs Chapter 11

This article first appeared in the January/February 2024 issue of the Journal of Light Construction.  www.jlconline.com

The International Residential Building Code is supposed to provide clarity into how builders construct homes.  In the IRC’s own words, The IRC was created to serve as a complete, comprehensive code regulating the construction of single-family houses, two-family houses (duplexes) and buildings consisting of three or more townhouse units.”  Usually, the codes do a decent job giving us options on how we should build homes with the occupant’s safety and health as our number one priority.  Codes also address energy efficiency and building durability.  Sometimes though, codes can be quite confusing.  How we handle vapor retarders when using continuous insulation is one of those areas.

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A 2021 IRC Code Oversight Could Lead to a Risky Roof Assembly

This post first appeared on the Green Building Advisor Website.

I’ve been working on a future article for Green Building Advisor that has a working title of “Problems with Attic Trusses”.  During research for the piece, I found myself reviewing the ratio rules for hybrid roof insulation strategies.  GBA has two really good articles on the topic:

Combining Exterior Rigid Foam With Fluffy Insulation – GreenBuildingAdvisor by Martin Holiday

The Ratio Rule for Hybrid Roof Insulation – GreenBuildingAdvisor by Allison Bailes

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Membranes…Interior Air-Control Strategies That Can Work

This article first appeared on the Green Building Advisor Website.

I’m from Minnesota, one of the few areas in the lower 48 that still regularly uses polyethylene sheeting as a vapor retarder, we’ve become very good at detailing these interior membranes for use as an air barrier.  (The practice is also very common in Canada and Alaska.)  The average blower door test I conduct for new homes in my market has now moved below 2 ACH50, most achieving these scores only using an interior air control strategy.  I don’t recommend using poly in most cases, instead I suggest moving to a class II vapor retarder, (smart, variable, and responsive vapor retarders), these products can also be used for air control.  Installing the two products is similar, so, what are the tricks to an effective interior air barrier installation?

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Peak Electricity Load Control Programs-a Solution for Home Electrification?

There are times during the day when electrical demand is high, during the morning when a large portion of the population is getting ready for work.  The lights come on, there’s an increase in hot water use, people are making coffee, or using the microwave or an electric stove or oven.  All these add to a morning increase in electricity demand, a peak in usage.  A similar increase occurs in the evening when people return home from work.  The weather can also influence electricity demand, hot weather will increase the need for air conditioning and maybe dehumidification.  Overnight usage is typically low periods of demand.

The hourly electricity consumption from an actual energy audit I recently conducted showing increased usage based on time of day.

A problem with periods of high electricity demand, utility companies often need to bring peaking plants (short term power generating plants) online to satisfy short periods high electricity usage.  These power plants are sometimes only used during peak loads and often have higher air pollution rates than the plants designed to operate all the time.  If demand isn’t met by the peaking plant, the provider must purchase power on the open market.  Sometimes the electricity rates during peak electricity usage are purchased for dollars per kilowatt, and then are sold back to the customer in pennies per kilowatt.  Not the best business model. Continue reading “Peak Electricity Load Control Programs-a Solution for Home Electrification?”

What you need to Know About Radiant Heating

In-floor radiant heating systems are popular in my very cold climate.  Many new homes are being constructed as slab on grade with only one level, a perfect place to use an in-floor heating system.  (I’m a fan of pairing radiant in-floor heat with an air source heat pump.  The heat pump will supply any needed cooling along with the heating load during spring and fall, more on that in a bit.)

Hot water tubing ready to be cast into a concrete slab.

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How to Plan for Continuous (Exterior) Insulation on an Existing Homes

This post first appeared on the Green Building Advisor website.

When I purchased my small 1950’s vintage Cape Cod home in 2018, I knew I had a lot of work to improve its performance and comfort.  I was planning a multi-year, self-performed (and solo), deep energy retrofit.  A case study where I could learn and share the difficulties of such an endeavor. 

One of my goals was to improve the insulation levels of both the walls and roof.  I went back and forth trying to decide if I should add a layer of continuous insulation to the exterior.  After all, I was going to remove the existing siding and replace all the windows.  In the end, I decided against it.  The gable ends of my roof have no eave (see photos below), adding exterior insulation would have required me to rebuild a portion of the recently re-shingled 12/12 pitched roof.  I now regret that decision, more on that later.

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In the Spotlight-The Biggest Mistake of All

This short piece was recently published in Fine HomeBuilding Magazine-Issue 321/February-March, 2024

www.finehomebuilding.com

In one way, a builder’s job is simple; Provide a structure that is safe and resilient and meets the basic needs of its owners or occupants.  But today’s homes are intricate systems.  Over the past decades, building enclosures have evolved with layers of complexity, heating and cooling systems have become more sophisticated, and new mechanical ventilation systems, meant to provide healthy indoor air quality are often misunderstood by the people living in the home.  Because these systems work together, it’s important that the owners understand how they operate, how they are maintained, and who to contact when there is a problem.  Unfortunately, homes rarely come with an owner’s manual.

The complexity of a modern heating system.

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Wood Fiber Insulation-How It’s Made to be Fire and Rot Resistant

Recently, I was invited to a BS and Beer meeting (BS stands for Building Science) at a home under construction near Kansas City, MO.  The meeting featured an installation demonstration of TimberHP’s TimberFill wood fiber insulation.  This new loose-fill wood fiber insulation was being blown into the attic and dense packed into the walls.  Two representatives from TimberHP, Business Development Manager Dan Edelman and Field Education Specialist Matt Damon were on hand to answer any questions and teach the installing contractor the best practices for installing the TimberHP’s loose fill insulation.  Being a new product, there were many questions during the BS and Beer meeting.  The most common where:

Doesn’t wood fiber burn?

What happens if the insulation gets wet?

How do you keep bugs from destroying the product?

Lucky for Dan and Matt, all three questions are answered the same, the product uses borate.  So, what is borate?

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Northern Built Pro’s Top 5 Blog Posts for 2023

Happy New Year!  2023 was a good year for the Northern Built Pro website with 45 new blog posts, many first appearing on the Green Building Advisor website, and some that ended up in a couple trade magazines, Fine HomeBuilding and Journal of Light Construction.  I wrote a few that were directly for manufacturers of building materials, including Rockwool, Andersen Windows and Doors and Sashco.  I am looking forward to partnering with a few additional manufacturers in 2024.  A teaser to one that I am currently writing an article about, TimberHP.

These are the top 5 blog posts that were written and published in 2023.

5.  The Diminishing Return of Insulation

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An Airtight Home, What Do the Blower Door Numbers Mean?

I recently had the opportunity to attend a BS and Beer meeting in Kansas City, MO where the meeting took place in a home under construction.  The home was being built by Aarow Building (Jake Bruton) of Columbia, MO (they recently opened an office in Kansas City).  The home is a single level, slab on grade with around 3,250 square feet.  At the time of the meeting, the home was just finishing the mechanical, electrical, and plumbing systems and about to move to the insulation phase.  A perfect time for a mid-build blower door test.

The purpose of a mid-build blower door test is to confirm that the home is on track to meet the air tightness metric (Jake informed me that all his new homes are contractual bound to achieve 1 ACH50 or less) and to find any missed opportunities in the air sealing of the home.  The mid-build testing can be simple, get the home to negative or positive 50 Pascals of pressure and record the CFM rate, this type of testing is called “single point”.  If you feel the CFM rate (or the calculated air changes per hour at 50 Pascals number) is too high, set the fan on “cruise control” and go find the air leak locations.  There’s no need to perform multi-point testing this early in the build, (a type of blower door testing where CFM rates are measured at progressively lower pressure points, usually starting at 60 Pascals), save that type of testing for the final blower door test. Continue reading “An Airtight Home, What Do the Blower Door Numbers Mean?”