The Diminishing Return of Insulation

Insulation and R-value go together like hard work and sweat.  R-value is, of course, the resistance to heat flow.  We’ve been taught to think more is better, which is true to a point.  I’m changing the insulation in the wall of my home from R-7, originally installed in 1952, to R-15, and I’m excited to see how much more comfortable my home becomes.  There is an argument that at a certain level, more insulation will cost dollars to save pennies.    At what point do we reach diminishing returns?

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What is R-Value?

This is the first in a series of blogs I’ve written for Rockwool and the R-Class Builder Program.  If you are not already a member, you can join at this link, Rockwool R-Class.  The R-Class program is free.

What is R-value?  I write often about different insulations, how they perform, where they should and shouldn’t be used.  I think this blog post should go back to the basics and talk about what is R-value, how it is calculated, and how much is needed.

This concrete foundation is not insulated, concrete has a much lower resistance to heat flow (R-Value) than the insulated wall. This becomes evident when using thermal imaging. Heat is leaving this structure through the concrete. Insulation will slow this heat loss.

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Construction Design-Wind Washing

Wind: The natural movement of air relative to the planet’s surface.

Washing:  A method of cleaning.

Wind Washing:  Cleaning using air?

Well, not quite.  Wind washing with regards to insulation is the ability of air movement to degrade the effectiveness of an insulation.  We will get to that in a little bit.  First a quick lesson on how fibrous insulations works.

A close-up of Rockwool ComfortBatt showing the fibers and small air pockets.

We use insulation to slow the movement of heat through our building assemblies.  Heat will move in three ways, conduction (heat moving when objects are in contact with one another), convection (heat transferred by moving air), and radiation (heat moving through spaces).  Fibrous insulations forces heat to move through fibers and small pockets of air, which slows heat movement in both radiation and conduction and prevents heat transmission by way of convection. Continue reading “Construction Design-Wind Washing”

Construction Design-Conditioning an Attached Garage

This post is the unedited version of an article I wrote for Fine HomeBuilding magazine which appeared in the December 2021/January 2022 issue.  My original version was more focused on garage designs for heating dominated climates, FHB helped to make the article relatable to other climates.  The link will bring you to the printed version.  FHB304-ConditioninganAttachedGarage.pdf (finehomebuilding.com)

I consider the attached, heated garage a luxury item.  I used to have one, it was nice not having to scrape ice or clean snow off my vehicles.  Having a warm car when its below zero outside was also nice.  But I was paying for that luxury, around $100 per month for energy costs in December, January, and February.  There was also the added cost of the heating equipment and extra insulation needed when building the space.  And lastly, there was always moisture in the space, both in liquid and vapor that needed to be dealt with.

This attached garage has a bonus room above, separation between the garage and home is important for both the durability and indoor air quality of the home.

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Construction Design-The Effect of Windows on Wall R-Values

I’m about to start a remodel project of the family room in my home.  Not your normal fresh paint and new floor covering update, but a complete gut down to the stud renovation.  New electrical, new drywall and no more popcorn ceiling.  I’m curious as to what my effective R-value of the exterior walls will be when I’m done with the space.  This includes the windows.  I figured I’d share my calculations with you.  This post is math heavy, if you’d like to skip the math, read the final five paragraphs.

Progress picture of the exterior work on my small cape from 2019.

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Construction Design-Heated Floors and Floor Coverings

Best Choices and What Should Be Avoided

One of the first jobs I had when I started my career in the construction industry, back when I was working as an electrician, was installing electric resistance heating cables for a basement heating system.  It took two people, one person pulled (me) while a second person pushed (my brother) and guided a small manual plow which installed electric heat cabling just under the surface of a sand layer.  Concrete would then be poured over the sand; the result would be a heated floor.  As it turned out, there was a high percentage of cable failures with this system, which resulted in many people having to install a new heating system.

Hot water radiant heat in a slab on grade home.

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Construction Design-Flashing Details and the International Flashing Awareness Day 2022

Late summer, 2021, Aron Jones (bigdogconstruction.gm on Instagram) and Gina Hoyt (bigdoglifex3 on Instagram) started the International Flashing Awareness Day to bring awareness to the importance of correct flashing details.  I participated by posting a failed assembly that was lacking correct flashing on my Instagram account.

This year the International Flashing Awareness Day is on Friday, August 26, 2022.  Instead of producing a quick post for Instagram, I decided instead to write a blog covering the subject of flashing in construction.

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Construction Design-The Anatomy of a Well-Built Wall

I’m a fan of mineral wool insulation, specifically the Rockwool brand.  Over the next few months, I’ll be writing a series of blog posts discussing tips, tricks and the tools used to work with this insulation made from rocks and steel slag a byproduct of the steel industry.  Before we get into those topics, I want to discuss the Rockwool products I use, the building science behind the how these products work in a wall and the characteristics of the insulation, all of which can create a well-built wall assembly.

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Construction Design-Frost Protected Shallow Foundation (FPSF)

This post first appeared at the Green Building Advisor website.

One of the most popular foundation systems used in my market, and one I’ve been using for more than a decade, is the frost protected shallow foundation.  My very cold climate requires footing depths of five feet.  Digging, constructing and insulating a footing and foundation system that deep is time consuming and expensive.  A shallow foundation system can be a substantial savings for a new build.

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Construction Design-Mechanical Room

This post first appeared on the Green Building Advisor website.

I’m one of those nerds that politely tour a new home looking at all the fine trim work and fancy finishes, but secretly can’t wait to get the mechanical room.  (Sometimes I even have to ask to see it.)  If that room is well laid out and neat, I feel I’m in a quality home.  It’s been a few years since I’ve worked full-time as an electrician, but I still remember the frustrations of being on a new build or working in an older home where there just wasn’t enough space in the mechanical room for all the equipment.  The trades working together (more often fighting) for that last piece of wall space to fasten their equipment is something I experienced many times.

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