Why Knowing Your Climate Zone is Important

Figure N1101.7 (R301.1) Climate Zones-2021 International Residential Code (IRC)

This climate zone map is published by the American Society of Heating and Air-Conditioning Engineers (ASHRAE) and is included in the International Residential Code, chapter 11, Energy Efficiency.  ASHRAE’s purpose is to create standards of how an engineer or HVAC professional calculates and designs heating, air conditioning and ventilations systems to match the insulation, air sealing, and moisture profile of a building.  When designing these often-complicated systems, where the structure is located becomes key, this is the reason the map was created.

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Upgrades that Effect Energy Loads

This post first appeared on the Green Building Advisor Website.

As homeowners, builders, and/or designers, how do we choose the right products or assemblies that provide the best energy performance?  How does a code minimum designed wall perform?  How about changes in ceiling insulation R-values?  What if we decide to increase the air tightness?  How about triple pane windows?  There are several ways in which product and assembly upgrades are chosen.

  1. First is experience. In having the opportunity to be in more than 100 homes a year performing energy assessments/audits and building investigations, I see both successes and failures.
  2. Being familiar with the different products on the market is important. As an example, selecting the right product for a given budget that can be installed over the board sheathing of an existing home to provide both bulk water management and air control.
  3. Using energy modeling software to quantify the decisions is helpful. The easiest way to decide which improvements to implement is by creating a baseline (code minimum) model of the project, then key in the proposed upgrades to see how the model changes.
Air leaks, thermal bridging, and low R-values all affect the operational costs and comfort for this home.

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Ice Dams-Why They Form and How to Reduce their Risk

There is a lot of confusion as to why ice dams form on roofs in cold climates.  This is understandable, some years we experience heavy ice dams, other years have little to no issues.  Changes in weather from year to year can have a major impact on their formation.  I’ve seen new homes with ice dams that are completely related to winter freeze/thaw cycles.  That being said, most ice dam issues are directly caused by certain characteristics of the home, namely insulation levels and air tightness.

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Construction Design-Problems with Attic Trusses

This post first appeared on the Green Building Advisor Website

Attic truss, also known as a room-in-attic truss are a way to create a living space without the need to add a full second story to a home.  These factory-built roof systems simplify a roof buildout and are engineered to meet the structural requirements of your local codes and conditions.  I commonly see them used for bonus rooms over garages and integrated into slab-on-grade homes to add living space without needing to add to the height of the building.

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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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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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Cavity Only Insulation-A Correction to the 2021 IRC Energy Code

This post first appeared on the Green Building Advisor Website

I recently wrote a two-part article covering the benefits, challenges and code requirements for continuous insulation.  (You can read the articles here and here.)  In the first article, I referenced table R402.1.3 which is found in Chapter 11, Energy Efficiency.  The table shows the R-value and U-factor requirements for several building components and assemblies.  The table data was taken from the first edition printing of the 2021 IRC.  In the article, I stated, “Climate zones 1, 2, and 3 are unique in that they have the option of cavity-only insulation.  Climate zones 4 through 8 all are required to have some amount of continuous insulation.”  A reader on the Green Building Advisor Website, jimmybpsu, pointed out in the comments section of the article that he had a different version of table R402.1.3 which did allow for cavity only insulation in climate zones 4-8.  As it turned out, he was right.

My son Colter installing a R-30 Rockwool Batt.

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What You Need to Know About Continuous Insulation-Part 2

This post first appeared on the Green Building Advisor website.

In the first part of this continuous insulation blog, we covered building codes and some building science and how they relate to CI.  This second part will discuss some of the difficulties many builders have with how the details work.

I remember my first time using continuous insulation in a new home.  I had many questions; where to put the WRB, how to attach the cladding, how to address the windows and doors, and how much insulation to use.  That home is now more than a dozen years old without any complaints from the homeowner.  Would I change some of the details I implemented on that first CI home?  Absolutely!  But the design and execution all those years ago seems to be performing.

Photo by Armando Cobo

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What You Need to Know About Continuous Insulation-Part 1

This post first appeared on the Green Building Advisor website.

Living in a very cold climate where wintertime temperatures colder than -20°F aren’t uncommon, you would think contractors and homeowners in my market would be excited to use continuous insulation (CI) on every new home under constructed along with every existing home having the exterior cladding replaced.  In reality, I rarely see either happening.  Part of the reasoning, my state and local building codes don’t require CI.  Cost is another driving factor.  As both homeowners and builders become better educated on the benefits of CI, this should start changing, I’m advocating for its inclusion on projects I’m involved in.

There are many reasons to use continuous insulation.  Reduced energy consumption is one benefit, though lowering heating and cooling costs are, in my opinion, less important and a secondary reason to add CI.  Improving comfort (thermal and sound) and expanding durability are more important.  (I’ll get into durability in detail later in this article.)  Building codes have begun to align with building science and we are seeing more areas across the country adopt continuous insulation as part of the energy code.  The scary part for most builders is the unfamiliarity of installing insulation on the exterior of a wall.  What insulation can be used?  What thickness and R-value are required?  How do I detail window and door openings?  How do I secure the insulation?  How do I attach the cladding?  Where does the house wrap go?  What about other penetrations such as exhaust vents and electrical penetrations?  What about the vapor retarder?  We will be discussing these topics and more over the next two articles.  In this post, we will be discussing the building code requirements along with the building science principles covering CI. Continue reading “What You Need to Know About Continuous Insulation-Part 1”