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-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 Materials-Cavity Insulation

Heat wants to move from someplace hot to someplace cold.  It’s desire to reach equilibrium is one of the principles of the second law of thermodynamics.  We have many methods and materials we use in construction to try to slow this movement.  It’s expensive to condition a space and we want to hold on that space conditioning for as long as possible.  One way we try to slow heat loss or gain is to prevent the wind from blowing through the home.  Another is to shade the sun from beating through a window on a hot, sunny day (in some climates at certain times of the year, the sun can be a blessing).  Insulation is one of the big ones we use to provide comfort to homeowners.

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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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Barndominium Part 4-Insulation and Air Control

This post first appeared on the Green Building Advisor website.  Residential Post-and-Frame Construction, Part 5: Insulation and Air-Sealing – GreenBuildingAdvisor

Cavity Insulation

I was brought on the barndominium construction team after many decisions were already in place.  The design was, for the most part, finished.  Many of the assemblies had been designed, such as the decision to use laminated posts six foot on center with the horizontal wall girts both inside and out.  The original plan for the insulation was to use up to seven inches of closed cell spray foam in the walls.  I was able to change the insulation strategy with a plan for a more “forgiving” assembly.  We chose to go with Rockwool’s 7.25-inch ComfortBatt, which has an insulation value of R-30. Continue reading “Barndominium Part 4-Insulation and Air Control”

Building Science-Ice Dams

This year seems to be a good (or bad depending on how you look at it) year for ice dam problems in my area, the intensity of ice dams seems to change year to year.  I was recently on an ice dam diagnostic with an insulating contractor and a general contractor, the home was built in the early 1990’s and there is evidence there have been issues from the beginning.  We spent a couple hours testing this home, I’ll get into what we found in a bit.

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Building Science-Existing Construction Improvements

This three-part series first appeared on the Green Building Advisor website and has been condensed into one post.

An unconditioned and uninsulated crawlspace, an unsealed and uninsulated forced air heating system, and an uncovered dirt floor, which by the way has a sewage leak.  If this were your home and you wanted to make improvements, where would you start? Continue reading “Building Science-Existing Construction Improvements”

Construction Design-Using Fibrous Sub-Slab Insulation with In-Floor Heat

I’ve written about sub-slab insulation and heated floors several times over the past couple years, this post is about something I’ve been thinking about for a while now, using a fibrous insulation, like Rockwool’s ComfortBoard 80 or 110 under a concrete slab with hot water heat.  The questions I had about this strategy are one, will there be an issue with compression of the insulation when concrete is poured over the product?  And two, will a staple be able to hold the hot water tubing in place?

Rockwool ComfortBoard being installed below a concrete slab.  Photo by Travis Brungardt

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Construction Design-Closed Cell Spray Foam Below a Slab

This post originally appeared on GreenBuildingAdvisor – Green Building Advisor is the one-stop source for builders, remodelers, architects & homeowners looking for expert advice on green products, strategies & proven construction details.

I was introduced to using closed cell spray foam (CCSF) below a slab a few years ago by New England contractor Wade Paquin of WKP Construction. He was insulating the below grade slabs of his new homes by spraying a couple inches over a bed of stone, then pouring the concrete. I have now had the opportunity to try this insulation method over a couple projects, Continue reading “Construction Design-Closed Cell Spray Foam Below a Slab”