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I have been helping the parents of a friend visualize a basement remodel project, where they are going to be claiming a portion of the basement for living space.  Therefore while helping them, it has brought me back to a few article written on how to properly insulate your below grade walls.  Building Science Corporation has lots of good articles on the subject (here & here), however I will bring your attention to an article that talks both about the good and the bad systems used.

RR-0202: Basement Insulation Systems

by Building Science Corporation

The Problem

Meeting Energy Star levels of performance is one of the criteria for constructing homes to Building America levels of performance – levels defined by the Building Science Consortium and others.  Homes constructed with basements require some degree of basement insulation to meet Energy Star.  As a result all Building America homes with basements constructed by the Building Science Consortium have basement insulation.
In any event, heat loss from basements accounts for such a significant portion of the energy loss from a home that it is clear that a home with a basement must have basement insulation to be called “energy efficient.” Additionally, in many jurisdictions, basement insulation is a building code requirement.

Finally, most homeowners with homes with basements finish the basement area for additional living space.  When they do, they typically insulate the perimeter walls.  Homes with basements often end up with basement walls that are finished and insulated.

There are only three ways to insulate a basement wall: on the interior, on the exterior or in the middle.  Of the three,
the most common approach has been to insulate basements internally.  The reasons for this have been due almost strictly to cost.

Continue reading the article at buildingscience.com

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Now this article talks a little about hiring the right professional when you are having problems with your home as the one in the article.

Don’t Try This At Home:  Armchair Building Science.

By Peter Yost via GreenBuildingAdvisor.com

Is the mold on the plywood in this attic the result of inadequate attic ventilation or air leakage?

The homeowners called me after a certified home inspector stated the former; that the attic was underventilated and moisture was building up as a result. The roof assembly had soffit vents at the eaves and two gable end vents. Not as effective as ridge-to-soffit ventilation, but probably close to building code requirements (see Green Basics – Attics).

I did not have the time to get down to the home to take a look myself, so I asked the homeowner to send me photos of the house and the problem. Bit dicey to diagnose a problem and give guidance over the phone based on a short series of photos, but armchair building science is an honorable pastime.

Continue reading the article at GreenBuildingAdvisor.com

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A great article that should help all of us to build a better performing wall for our clients.

BSI-001: The Perfect Wall

By Joseph W. Lstiburek

The perfect wall is an environmental separator – it has to keep the outside out and the inside in.  In order to do this the wall assembly has to control rain, air, vapor and heat.  In the old days we had one material to do this: rocks.  We would pile a bunch or rocks up and have the rocks do it all.  But over time rocks lost their appeal.  They were heavy and fell down a lot.  Heavy means expensive and falling down is annoying.  So construction evolved.  Today walls need four principal control layers – especially if we don’t build out of rocks.  They are presented in order of importance:

• a rain control layer
• an air control layer
• a vapor control layer
• a thermal control layer

A point to this importance thing here, if you can’t keep the rain out don’t waste your time on the air.  If you can’t keep the air out don’t waste your time on the vapor.

Continue reading the article at buildingscience.com

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Here is an article that I found very useful on a recent project where the goal was to drastically improve the performance of a home, as well control the moisture levels within the crawl space.

BSI-009: New Light In Crawlspaces

By Joseph W. Lstiburek

Crawlspaces stink, they rot, and are just plain icky.  Photograph 1 shows the modern crawlspace, which is a forest of water droplets on the underside of fiberglass batt insulation.  The exposed wood floor joists are rotting.  The house over this crawlspace is not shabby.  Did I mention that this is a vented crawlspace?  Oh, by the way, there is a continuous plastic sheet ground cover and excellent drainage.  Everything in this crawlspace was done “right.”  It has code specified ventilation, a continuous impermeable ground cover, excellent drainage and still we have a mess.  What caused this mess?  The floor insulation.  No way.  Yup.

Photograph 1: Icky Crawlspace—Note the condensation on the underside of the fiberglass insulation and the rot at the exposed portions of the crawlspace floor joists.

Continue reading the article at buildingscience.com