This Log House - Entry 4

The problem: how do you balance the beauty of exposed old logs with the desire to heat the building with as little purchased energy as possible -- and meet or exceed the RESNET home energy standards (http://www.natresnet.org/)?

Wood is a rather poor insulator. Although the mass of the 7” thick old-growth oak heartwood log walls does absorb and release heat, providing somewhat more thermal comfort than indicated by their nominal low R-value, that doesn’t mean there is adequate insulation. The insulating quality of traditional chinking (the “filler” between the logs) is even worse.

Our solution: leave the logs exposed on the interior for parts of the southern and eastern walls – the living room, dining area and morning coffee alcove -- then super-insulate the rest.

In every wall of the house, the spaces between the logs have been packed with insulation, awaiting the application of modern chinking material (yes, there is such a thing) to the exterior, as well as to the exposed interior walls. The interior face of the remaining walls has been covered with rigid polyisocyanurate (R-6.5 per inch). Parallel stud walls, filled with the same material, will soon be paneled with old beaded boards recovered during dismantling of the log structure. The resulting R-29 walls largely offset the low insulating value of the exposed areas in the log structure, and combine with the insulated concrete form (ICF) foundation to make the total structure energy efficient.

Other components: layers of insulation adding up to R-52 between (and on) the attic floor joists, insulation on the band joist (rim joist) of the structural deck supporting the house, and extra caulking in other places where cold air could infiltrate. The foyers on the living and garden levels are essentially air locks to keep cold air from sweeping in when the outside doors are opened.

It’s snug.