We got our almost-final schematic drawings for the house done. We hadn’t had a design for the offices and guest room in the attic that we liked yet. Dan and Todd (Olson Kundig) got help from Tom and now looks pretty good. The whole design needs just minor edits (moving a door here, rotating a toilet there) and we feel great about it. Now we need to think about what we’re going to do with the garage.

We’ve been working on the windows and insulation decision. The windows are all muntin-free and all are encasements, not single- or double-hung, so that’s great for preventing leaks. The windows are all in great condition, considering their age, so the window contractor suggested repairing the existing windows where necessary rather than replacing them with modern windows. I like this because it’s much cheaper to repair than to replace them. Plus, original windows look better than modern windows.

All the windows are single-pane, which aren’t as good as dual-pane for insulation, but dual-pane windows aren’t all that much better insulation-wise and they don’t last as long as single-pane windows. 20 years is about the lifespan of a dual-pane window and the windows in our current house are proving that.

All the walls in the house lack insulation, which wasn’t popular until the original US energy crisis in the 1970s. Insulation is great for lowering the heating bill, but terrible for the longevity of the house. Insulated walls prevent the walls from breathing so condensation that forms inside walls stays and, of course, water is the enemy of wood so the wood rots. This is one reason modern houses don’t last as long as older houses – the wood deteriorates more quickly in modern homes. Water is also bad for insulation, so over time, the insulation breaks down, stops insulating as well and requires replacement.

We have to decide whether saving on the heating bill is more important than preventing rot in the house’s structure. I’d like the house to last another 100 years, so I’d prefer to not be the people who started the deterioration of the house. The contractors suggested a happy medium: only insulating the bedroom exterior walls to keep the bedrooms warmer at night. The 2nd floor is also easier to insulate because the first floor has a lot of great old wood trim on the walls that we don’t want to disturb. The house has radiant heating, which is about as efficient as you can get already, so it’d take even longer to make insulating the walls cost-effective. I’m not even sure it’s necessary comfort-wise. Seattle rarely gets very cold and people have lived in the house for 100 years, so how cold could the house get?

The biggest cause of heat loss is infiltration (leaks in the envelope of the house) and heat lost through the roof. So we’ll plug all the leaks and insulate the attic ceiling and get the biggest energy-efficiencies that way. We need to do more research before we make a decision on insulating the walls.