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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Indoor Air Quality and Building Diagnostics

The post originally appeared on the Green Building Advisor website.

I recently purchased the CPS IAQ PRO SmartAir professional indoor air quality meter to use during energy audits and building diagnostics/investigations.  My intent with the purchase was two-fold, first to learn more about indoor air quality metrics by testing homes in my market, and second, to have a more accurate temperature/humidity/dew point estimation inside these homes.  I recently had the opportunity to use the tool on a building investigation, I’ll outline this case study later in this post.  First let’s talk about the features of the CPS IAQ PRO SmartAir.

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Why You Need Blower Door Testing

This article first appeared in issue 304 of Fine Homebuilding Magazine.

I bought my first blower door in 2009, back when new construction was in a downturn and energy auditing and weatherization projects were on the rise.  I took a 40-hour energy auditing training course at a local college which included hands-on training on how to use a blower door.  It took many tests before I became comfortable in its operation and understood the information it was providing.  Though one of the more expensive tools I own, I’ve been able to keep it busy and add this specialized testing to my business’s income stream.

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Duct Tightness Testing

This post originally appeared on the Green Building Advisor website.

Testing air leakage in ductwork used for forced air heating and cooling systems has been required since the 2012 IRC code.  The 2012 through the 2018 code allowed a testing exemption for all ductwork located inside the building envelope.  In other words, if you kept all ductwork inside the thermal and air boundary of the building, no testing was required.  That has changed for the 2021 energy code.

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Construction Materials-Success with Construction Adhesives

This post first appeared in the December 2022/January 2023 issue of Fine HomeBuilding Magazine.

For hundreds of years, adhesives were created with organic compounds made from animal parts and natural resins for wood joinery, book binding, and other tasks requiring materials and surfaces to be bonded together. Today, most construction adhesives are made with synthetic acrylic resins, polyurethane monomers, hexane, and other nonpolar solvents, all man-made compounds.  Modern adhesives are used extensively by manufacturers, builders, and homeowners, and some form of them can be found in nearly every product around you.  While adhesives are available in buckets, sticks, drums, tubes, cartridges, and more, this article will concentrate on the fluid adhesives often used in construction and commonly found at hardware stores, lumberyards, and home improvement centers; the differences between them; and how each of them should be used. Continue reading “Construction Materials-Success with Construction Adhesives”

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 Materials-Airtight Electrical Boxes

Working as a residential electrician back in the late 1990’s, I remember learning of a new electrical box that we were asked to use on all exterior walls and in the ceilings of unconditioned attic spaces.  At the time, they were called “vapor tight” boxes.  These boxes were designed to reduce air movement through wall or ceiling cavities by sealing the electrical box to the wall or ceiling air barrier and also to seal the electrical wires where they enter the box.  Air will contain at least some water vapor, by air sealing the electrical box, we were also reducing the amount of water vapor that could potentially enter a wall or ceiling.   The name “vapor tight” was at least partially correct.

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Building Science-Window Condensation

As I write this blog, a good portion of the nation is experiencing very cold temperatures with high winds.  I’m currently sitting at -9°F with a windchill or feels like temp of -38°F.  Chatting with a good friend in Kansas City recently, he was impressed by the below zero temperature readings.  (He was actually begging me to stop sharing and keep the nasty weather in Minnesota.)  Because of the weather, I’ve been receiving emails and DMs on Instagram about how people’s houses are reacting to this weather extreme.  Window condensation has been one of the more frequently asked questions, so I figured I’d cover that topic in a blog post.

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Diagnostic Tools-Indoor Air Quality

There are currently a few hot topics around the construction industry, the high efficiency heating and cooling system called a heat pump is one of the biggest.  Cross laminated timbers (CLT) are an engineered wood product that is getting a lot of attention in the commercial side of construction.  I’m hearing some noise about a few builders wanting to try the technology in the residential market as well.  And then there’s indoor air quality.  Since the start of the pandemic, there has been a lot of attention on how to make the air in our homes more healthy.

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Building Science-Natural Air Leakage

This blog first appeared on the Green Building Advisor website.

When conducting a blower door test, one of the ways we express the findings is with air changes per hour at 50 Pascals (ACH50).  As an example, a new home is blower door tested and found to be 2.75 ACH50, this means the entire volume of air inside the home is exchanging with the outside air 2.75 time per hour at the test pressure of 50 Pascals.  When discussing blower door testing with builders and homeowners, it can be hard for them to relate to the ACH50 number other than they know the home needs to be less than a certain level of air tightness to meet current code requirements.  Expressing the tightness as natural air leakage can sometimes be helpful.  How can we calculate the natural air change rate?  Well, there’s a formula:

ACH50/n-Factor = ACHnat Continue reading “Building Science-Natural Air Leakage”