Tag: Air Control Layer

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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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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”

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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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Construction Design-Service Cavity

This post was first published at www.greenbuildingadvisor.com.

There are many methods used to make a home airtight, it all comes down to one simple rule, continuity.  Continuity is easily attained when there’s nothing that penetrates the air barrier.  No electrical boxes, plumbing drains and vents or ducts that need to extend from inside a building’s envelope to the outside.  Of course, there are times when different things need to extend from inside to outside, like the need for an outside water faucet.  But there are also many occasions when different systems end up outside that don’t need to be outside.  For example, forced air heating and cooling ducts that leave the conditioned space of the home simply because there was no space to keep them hidden inside the home.  Planning a service cavity can help keep most mechanicals inside the building envelope. Continue reading “Construction Design-Service Cavity”

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Construction Design-Randy’s Dream Design

Guess what?  I just won the lottery!  (Not really, but for the purpose of this blog, let’s pretend.)  I’m looking to build myself a new home.  I have choices.  I could build a McMansion with plenty of space I don’t need and will never use.  I could concentrate only on the interior finishes and how the house looks.  If you’ve ever read my blog, you already know what direction I’ll take.  The house won’t be big, a couple thousand square feet is plenty for me, maybe a rambler with a second story over part of it built on a slab, no basement or crawlspace.  Being a BS* guy, I would make an invest in the stuff that is hidden, those pesky control layers I often talk about.  It would be based on the Pretty Good House concept. Continue reading “Construction Design-Randy’s Dream Design”

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Construction Design-Interior Air Barrier? Exterior Air Barrier? Or Both!

When designing the concrete-less slab on grade home, I gave serious thought to the location of the air barrier.  I have used water resistive barrier (WRB) or house wraps for years without a good understanding how they work as an air barrier.  In my climate, most homes use polyethylene sheeting as an interior (and main) air barrier.  As it turns out, there are better choices. Continue reading “Construction Design-Interior Air Barrier? Exterior Air Barrier? Or Both!”