Fast-Tracking a Pop-Top Addition - Continued

We measured the floor deck and found that it was about 2 inches out of square. This wasn't a surprise: I had known something was off when I measured the house during the design phase. Instead of trying to figure out the exact problem then, I'd had the panel producer make the panels as if the house were perfectly square. I knew we could make field modifications later.

The out-of-square floor deck required that we shorten one wall panel and extend another. The process was easy: With two guys working, the alterations took about 10 minutes (Figure 5).

Figure 5. Because the existing floor was 2 inches out of square, the crew had to lengthen one wall panel by removing the last stud (A), cutting off the plate (B), and replacing the stud (C). Another panel was lengthened with plywood spacers (D).

We finished out the day straightening the walls. The panels come with a single top plate; you add the double plate to stitch the wall together, then plumb and string it or site it as usual.

We were lucky that we had great weather, because effectively tarping the second floor with the walls standing and no roof would have been nearly impossible. If rain had been in the forecast, I probably would have kept the crane on site and worked as long as necessary to set the trusses. With the trusses up, I could have tarped the structure; luckily, this wasn't necessary.

Thursday: Setting Trusses

The next day, while waiting for the crane, we installed a two-ply girder truss for a small intersecting gable over a bedroom bump-out (Figure 6). We knew having this in place would make setting the rest of the trusses go much faster. We also prepped the gable trusses and got some braces and spacers ready.

Figure 6. In preparation for the crane's second visit, the crew installed the girder truss for a small bump-out (A). The gable truss was prepped with building paper (B) and preinstalled blocking for the drywall ceiling (C). When the crane arrived, truss-setting moved quickly (D); note the vertical bracing for the gable truss, installed on the inside rather than the outside of the end wall.

When the crane arrived, we began by lifting the interior wall studs and the roof sheathing up onto the second-floor deck, then started placing trusses. With the first gable in position but still suspended from the crane, we installed temporary bracing. Most framers place vertical braces on the outside of the building, which requires ladders or staging, but I like to put them on the inside because it can be done easily from stepladders.

The rest of the trusses were set very quickly. To keep things moving, we typically have the crane lift the trusses in pairs. The timing works perfectly: While we're setting and bracing two trusses, the operator can pick up another pair and have them ready for us by the time we're done with the first two (Figure 7). We were able to stock the second floor with material and set all the second-floor trusses within the three-hour minimum crane charge.

Figure 7. Lifting trusses in pairs eliminates waiting: There's just enough time to set the two trusses, using precut braces marked with the layout (right), while the crane operator picks up the next pair. Unlike longer braces, the 491/2-inch-long pieces don't get in the way of the next trusses to be set.

Once the trusses were in place, we immediately started sheathing the roof. Handing the sheathing up from the second-floor deck, we tacked it in place, aligning the trusses as we went, then had one guy finish it off with a coil framing nailer. He was responsible for making sure all the sheathing was solidly nailed and that nothing was missed.

The main roof was completely sheathed by the end of the day. We could have stuck around for another hour or two and felted the roof, but with no rain in the forecast we went home.

Friday: Roofing

The roofers showed up Friday morning. They got started on the front side of the roof while we finished up filling in the valleys on the gable bump-out and installing subfascia on the back.

By noon the roof was shingled and I was able to breathe a little easier.

Planning Paid Off

The following week, we built the porch roof, finished off the interior partitions, and moved on to doors and windows.

The rest of the job was a matter of scheduling subs to bring it all together. The granite countertops and custom shower doors were templated the day before I left on vacation. When I got back, the countertops and finished flooring had been installed, so I just had to arrange for the plumbing trim-out and for final inspections, and complete a few items on the punch list.

The house had gone through quite a transformation (Figure 8). In addition to gaining an extra 1,000 square feet of living space, it now had a luxury master bath, a porch, a back deck, and a wood-burning fireplace.

Figure 8. The completed home (left) looks vastly different from the original structure and has 1,000 square feet of additional living space. The family-room addition on the back of the house (below) contains a cathedral ceiling and a wood-burning fireplace.

The project's $270,000 price tag might seem high, but in this area it's tough to find an existing home for less than $500,000, and you'd pay a similar amount for a 1/2-acre building lot — if you could find one.