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Building Science-Tight Homes and Negative Pressures, When Should We Be Worried?

This post originally appeared on the Green Building Advisor Website.

A couple years ago I was asked to perform a blower door test on a new home.  The home was small with a footprint of only 1130 square feet.  When the test was completed, the test report indicated an air leakage rate of 91 CFM at the test pressure of 50 Pascals, .33 ACH50.  Completely unexpected for this code-built house.  (I actually measured the volume of the home again and ran the test two more times before I was convinced I had an accurate test.)  The contractor contacted me some time later and indicated the homeowners were noticing air coming through the exterior light switches when the dryer was operating.  The dryer was producing close to the same negative pressure as my blower door every time it was being used, a negative pressure of about 50 Pascals.  Is this a problem?

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Building Diagnostics-Single Point vs Multi-point Blower Door Testing

This Article first appeared in the September/October issue of The Journal of Light Construction.

The main purpose of a blower door test is to confirm the integrity and continuity of the air control layer or air barrier.  I have a few different options on how to perform a test.  Which option I choose is dependent on the reason I am performing the test.

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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 Materials-Success with Construction Tapes

This post originally appeared in the August/September 2022 issue of Fine Homebuilding Magazine.  Choosing the Right Construction Tape for the Job – Fine Homebuilding

Walk through any modern construction project and you’re bound to see construction tape somewhere on the site.  Whether it’s taping the seams of a mechanically attached water resistive barrier (WRB), flashing a window or door opening, or making sure an air barrier is continuous, tapes have become a key part of many assemblies.  Mostly, we use tapes for two purposes, to keep something in, like the air we pay to condition, or keep something out, like water.  It’s important to use the right product for the right application.

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Construction Education-Construction Instruction

This post originally appeared on the Green Building Advisor’s website.  https://www.greenbuildingadvisor.com/

I recently took a trip to Denver, Colorado for a couple days of construction education, specifically a two-day class on high performance HVAC and IAQ.  The course was offered by Ci, or Construction Instruction and combined classroom learning with real-world, hands-on education in their adjacent testing center.

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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-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 Materials-Sealants

This post originally appeared on the Green Building Advisor website.  www.greenbuildingadvisor.com

I once heard Dr. Joseph Lstiburek use the term “pookie”, which made me chuckle.  He was referring to a fluid type product used to seal something.  In construction, we use a lot of different caulks, sealants, and adhesives, all of which are available in some sort of tube or bucket.  A walk through the caulking isle at any hardware store or lumber yard can make your head spin, what to use when and where.

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