Rooms Take Shape-Interior Framing

July 18-October 10: People seem to like big, open, vaulted spaces and many a visitor has “oohhed” and “aahhed” over the barn-like quality of my Poem Home. I almost hated to call in the crew to build out the interior rooms, but it was finally time. The first step was to install the missing strip of drywall at the ceiling. That’s the 12” gap down the length of the building where the insulation crew accessed the ceiling cavity just a few weeks earlier. 2Once sealed up, top plates were screwed through the drywall into blocking between the roof trusses and studs were dropped down to bottom plates anchored in the slab. At exterior walls, the framing was held 3/4” shy and the last stud left loose, so I could slip in drywall later.

This isn’t the usual sequence. Conventional practice has all the framing done before drywall shows up. But for a super-airtight house like mine, you take extra steps to shut down air movement. In the same way that you want your down parka to cinch up at the wrists and waist when you venture out in sub-zero weather, you want your exterior walls to block drafts—-whether those drafts come from outside or from the volume of air inside the building. Insulation works best in a dead-air cavity—-in my case 12” of it sandwiched between plywood and drywall. 7

To maximize space for insulation, and to save on the cost of wood, the interior walls abut “ladder blocking” instead of doubled-up or tripled-up studs. The crew from Wood & Stone got the interior walls up in just 2 days. Fitting sections of vapor retarder and drywall between the ladder blocking and the new walls was my job, and that took longer.

Here’s are plan-view sketches that explain why I took this extra step. In conventional construction, interior walls are attached directly to the exterior frame. The first sketch shows that when built this way, air can pass from an opening in an interior wall (like an electrical outlet) into the exterior wall. Even when packed with insulation, air can move through and carry with it warmth and moisture—wasting energy and risking condensation within the colder outside wall. In the second sketch, a continuous vapor retarder and drywall is in place before the interior wall is permanently attached, blocking air movement.

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In this house, the drywall serves an additional function. Just as I did for the ceiling, I need to have drywall in place before the insulation crew shows up next month to blow the walls. Conventional batt insulation (like pink fiberglass), can simply be placed in an open cavity but blown-in insulation like cellulose needs an enclosed cavity. One way to do that is to staple a fabric across the wall studs. But my crew asked for drywall, promising it would make for a better job and save money. I’ll need to leave them a 6” gap at the top of each wall and at the bottom of each window so they can access each bay with their tubes.

For the plumber, I built a half wall inboard of a section of drywall at the laundry so his pipes don’t use up space in the exterior wall better left for insulation. This also eliminates any risk of freezing and makes the plumbing accessible for future repairs or replacement.

Next, I installed 3/4” plywood blocking between studs wherever grab bars might be needed in the bathrooms. The blocking runs horizontally behind the toilet and continuously through the walk-in shower. Plywood also covers the 6 foot high shower wall on both sides, for vertical and/or horizontal applications.

It was Bob Rowen’s idea to secure the shower wall with a section of square stock. He sketched out a 5 foot long bar with metal plates and had a local shop weld it up out of stainless steel. It’s bolted through the end studs and to the loft floor above with T-nuts.

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While the walls went up fast, the details took time. Fitted out, the rooms have each taken on their own shape, and they feel right. The size and proportion of the bedrooms is pleasing, and the bathrooms work. The “great room” stills feels big, and with the loft in place (see next post)—still feels like a barn. And that’s a good thing.

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