Gail of Green Living


GREEN Medical Center Home For Sale: The Building Envelope

3703 Drummond

This is the third in a series of posts regarding the above property for sale in the Medical Center neighborhood called Braes Heights, in Houston.  This owner/builder has researched and studied so many products and methods of green building, that I’m sure we can all benefit from his research.  This week I’m summarizing his research on The Building Envelope, the backbone of  The Building System.  This is where the outside environment conflicts with the inside.

Traditional builders still use the wood framing method, which falls short in regard to durability (termites, wood rot, mold), and it requires added insulation.  Steel framing is quite expensive, and it’s difficult to find people who know how to do it.  It also requires insulation.  Thermal bridging is an issue with wood, and more so with steel.

SIPS (Structural Insulated Panels) are easy to manufacture and provide good insulation and strength.  They can be made to various sizes with window openings all pre-cut.  They are easy and quick to assemble.  The roof system can also be SIPs, with modest trusses, allowing for open and attractive interior spaces.  They do not suffer from thermal bridging, which is another plus.  The downside of SIPs is the fact that they limit the design of the home to a simple gable design with relatively few corners.

ICF (Insulated concrete forms) have been around for fifty years.  There are lots of manufacturers and this construction method is widely used in Canada and some northern states.  It is extremely strong, with 5″ foam insulation sandwiching 6-1/2″ of reinforced concrete.  Convection is not an issue and no termite wants to eat it.  The R-value of the system itself is about 25.  But when you take into account the thermal mass, the lack of convection or conduction and add in the radiant barrier/moisture barrier and air spaces, plus the exterior finish (stucco, stone or brick) and the sheet rock on the inside wall, the number is probably more like R-50!  There are no seams like in the SIPs system.  And a 14″ thick wall makes for a quiet home.  OK, this ICF has massive strength, the thermal mass, resistance to heat movement, sound dampening, resistance to convection moisture, bugs, wind, fire…so this is what makes sense!  The additional cost was $3/sq.ft over the cost of wood framing…amazing difference it makes!  They found a company in Texas that makes the product, BuildBlock ICF, and their service and reputation are first-class.

The roof information in my next post will amaze you!  Meanwhile, if you would like to see more photos and details of this beautiful home, click here or contact me for a personal tour.

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