COPYRIGHT 2017 JAMES DULLEY ( www.dulley.com/sea/ ) - March 2017 - (graphics ref. No. 259u at www.dulley.com/sea/column/2017-mar.htm ) "Select the best superefficient house construction technology for your new home" Dear Jim: We want to build our dream home using the newest, superefficient construction methods. Which ones can be built on a reasonable budget and are still very livable? - Brooke C. Dear Brooke: There are many new construction methods which are superefficient and worth considering, but don't immediately write off conventional stick-built lumber construction. To achieve high efficiency, wood framing techniques such as staggered double-stud walls, 2x8 framing and thick exterior rigid foam sheathing can be used. These improvements can significantly increase the construction costs though. Foam block construction is very efficient and these houses look like typical stick built houses. Large hollow foam blocks made for your specific house plans are stacked up creating the walls. The foam provides wall insulation levels as high as R-30. The blocks are designed such that there are open channels inside connecting them together. Once the lightweight blocks are stacked, which the homeowner can help with to lower costs, concrete is pumped up and into the top blocks. The concrete flows down throughout all the open channels to form a super strong rigid core when cured. The interior and exterior walls can be finished with any commonly used materials. A circular panelized house is another unique efficient design. For a given amount of usable floor space in a house, a circular house has less exterior wall area than a rectangular one. Cold winter winds flow smoothly around a circular house creating less pressure gradients and less air infiltration. Notice that most animals build their nests and dens with a circular shape. One unique circular house design uses self-supporting roof trusses with no interior supporting walls. This provides greater interior layout flexibility and an open floor plan. This is an advantage when using solar or other alternative supplemental heating. Heavily insulated, R-30, eight-foot long exterior wall panels create the circular appearance. Foam-core wall panels are another super insulated and airtight construction method. Structural insulated panels (SIPS) use thick foam sandwiched between two strong skins for up to R-45 insulation. They are designed for your specific house plan and locked together by various methods to create the walls. SIPS panels are strong enough to be self-supporting with no other extra framing. If you prefer to use wall framing or like the interior appearance of timber framing, for example, less expensive standard foam core wall panels are available. These are as efficient as SIPS construction. Steel-framed wall construction can be very efficient. Although steel conducts heat, the strong heavy red iron framing members can be spaced very far apart. This reduces the amount of uninsulated area (called thermal bridges) for better overall insulation levels up to R-40. Steel (mostly recycled) framing is extremely strong so the house never settles and stays airtight. It also offers architectural design flexibility. Geodesic construction is extremely efficient because the shape is spherical minimizing exterior area. One unique design uses thick foam blocks, up to R-60, which are attached together with supporting wood framing. Concrete is poured into steel reinforced channels. The wood framing is then disassembled and used for interior walls. These have withstood the most powerful hurricanes. Straw bale wall construction is certainly not a new method, but it's efficient and relatively inexpensive in rural areas where straw is plentiful. The straw bales are stagger-stacked, similar to bricks, with a long vertical steel rod through them to create the walls. The interior and exterior are usually finished with cement, plaster or stucco to create a strong attractive house. With two-foot thick walls, insulation is as high as R-50. Check your local building codes for approval with any non-typical construction method. Dear Jim: There are several gaps where the garage door meets the uneven floor. It lets a lot of cold air blow in when I work on my vintage sports car in my attached garage. How can I seal the gap? - Mark J. Dear Mark: Much of that cold air coming in also makes it through the walls and ceiling into your house. First try to adjust the door opener stop limit switch so door goes down a little farther and the seal is more compressed. If that does not help, buy a generic rubber weatherstripping seal for garage door bottoms. Another option is to nail a strip of 3/4-inch foam pipe insulation under the door. Attach it with the slit facing downward. Send your inquires to James Dulley, Publication Name, 6906 Royalgreen Dr., Cincinnati, OH 45244 or visit www.dulley.com.