Image Credit: Matt Bath Although the slab came out as planned in most respects, there were some areas that were less than perfect. Ideally, the outside of the bottom plate would have been in line with the edge of the slab. Framing for the entry door includes a single 2x10 header and a jack studs on each side to carry the load. Traditional framing (top) uses more lumber and leaves less room for insulation that advanced framing techniques (below). Fewer joints mean a lower potential for air leaks. Rather than end drywall in a corner, enough room is left between the end of a partition wall and the exterior wall to slide a sheet of drywall behind the partition. A powder-actuated tool uses a .22-caliber blank to fire a nail through the bottom plate and into the concrete.
Editor’s note: This is one in a series of blogs detailing the construction of a net-zero energy house in Point Roberts, Washington, by an owner/builder with relatively little building experience. You’ll find Matt Bath’s full blog, Saving Sustainably, here. If you want to follow project costs, you can keep an eye on a budget worksheet here.
After spending the weekend spraying the new slab down with water every hour or so, I was finally ready to get the walls up. The process of “wet curing” concrete for three to seven days can add up to 50% in strength because it prevents the water inside the concrete from evaporating. While many contractors begin framing the house the day after the concrete is poured, without experiencing any problems, I played it safe and waited until the third day to get going.
The first step was to snap lines on the slab where the walls would go. This will help keep the bottoms of the walls straight and square to each other. I took several measurements of the concrete, including the diagonal measurements from corner to corner, to decide where to start.
The slab came out really well, but not perfectly. (This is my first solo build, after all!) There will be a few small areas of concrete that stick out a bit or don’t come out far enough (see Image #2 below). This is no problem at all structurally and visually it will be covered up by the siding, but in taking these measurements I was able to position the walls to minimize the problem as much as possible.
The exterior walls will be framed with 2x6s. The first lines I snapped marked the inside edges of the bottom plates — 5 1/2 inches in from the edge. Once I had marked all the exterior walls, I grabbed the first sill plate from my pile of lumber and cut it down to 20 feet (most lumber yards give you an extra 1/2 inch or so). I lined it up on my line and marked out the anchor bolt locations, and then drilled them out. (Remember, the bolts were embedded in the concrete so just the top part stuck out) Then I set the bottom plate over the bolts and made sure it lined up just right. I repeated the procedure all the way around each wall until I had all four plates done.
With the placement of the exterior walls now set, I was able to measure out the locations of the interior walls and snap those lines as well. It will be much easier to mark them now, and they will serve as a sort of map to where my interior walls will be going.
Laying out the walls
I had to call a friend to help me carry the 32-foot-long laminated veneer lumber (LVL) top plate from the lumber pile over to the slab, and we set it on edge next to the bottom plate, which I had also turned on edge. I used some clamps to hold them together, perfectly lined up, and then used a tape measure to mark out the stud locations every 2 feet.
I had ordered the studs precut so that saved me a lot of time. I just had to carry them from the lumber pile and then inspect and “crown” them. Lumber, being a product of nature, is never perfect. I set aside studs with significant bends or waves for later use. The straighter ones I will use now, but even the straighter ones have a bit of a curve or “crown” in them. I lined the crowns up all going in the same direction, which will make it easier to straighten them out later in the build.
Once all the studs were laid out on my marks, it was just a matter of nailing them together. Building codes offer several different ways to satisfy nailing requirements, and the one I chose will be three 16d nails, top and bottom, to connect each stud to the top and bottom plates. I took my time and carefully aligned each stud to ensure that it didn’t stick out on either side. It is situations like these where even with my lack of experience I can guarantee I put together a better wall than 90% of the framing crews since they are focused on speed over quality.
For the window openings, a larger piece of lumber must be used to carry the load around the opening to studs on either side. Again, building codes offer several ways to satisfy these header requirements, and for mine I chose a single 2×10. I will also be utilizing some metal hangers to carry the weight of the header instead of shorter studs called jack studs, although I did use jack studs for the entry door (see Image #3 below).
Once all the lumber was nailed together, I unrolled some sill gasket and placed it on the slab where the wall would be anchored. I also nailed some long 2x4s to the top of the wall. As we raise the wall, these boards will swing out and brace it. The wall was very heavy but with a few friends we were able to get it airborne with ease. Once it was vertical, I staked down the bracing boards and then screwed the nuts down over large square washers on the anchor bolts.
Using advanced framing techniques
To an experienced framer, the work I have completed over the last couple of days would seem wrong. It is quite possible they would never have seen a house framed the way that I am framing mine. A few might even claim that I am violating building codes by not following “standard practice.”
The fact is, I am utilizing a method of framing created in the 1970s in a collaboration between the U.S. Department of Housing and Urban Development and the National Association of Home Builders Research Foundation. It’s commonly called advanced framing. The goal was to reduce the amount of wood used in construction, not only to save the lumber, but more importantly, to create more space for insulation and save on energy use. All of these small changes work to ensure the house will be net-zero.
In traditional framing you have a single sill plate at the bottom of the wall connected to a series of studs spaced 16 inches on center, which are then connected to two top plates sandwiched together (see Image #4 below). Even more studs are used to anchor interior walls to the exterior. All of the wood used are 2x4s, leaving a stud cavity 3 1/2 inches deep for insulation.
In advanced framing, on the other hand, only a single top plate is used, studs are spaced 24 inches on center and metal hangers are used instead of jack studs. On gable end walls, no headers are needed at all. “Ladder framing” is used to anchor interior partition walls, and 2×6 lumber is used instead of 2x4s, leaving 5 1/2 inches for insulation.
The advanced framing system is cheaper because it uses 5% to 10% less lumber, and it is faster because it uses 30% fewer boards (although they are a bit bigger and heavier). More important, every single year more money is saved on energy costs because more insulation can be used.
Okay, so what’s the catch? If advanced framing was added to the building code over 40 years ago, is cheaper and faster, and reduces energy bills every single month, then why isn’t it standard operating procedure for builders? How could I possibly be telling you that most builders don’t even know about it?
Most houses are built by a massive team of contractors who under normal circumstances communicate very little with each other, if at all. These tradesman are managed by a general contractor who uses building plans that were probably drawn up by an architect and edited by an engineer.
The changes in advanced framing may seem small, but they ripple right on down the line and affect every single person that works on the house. As contractors are paid by the job and not by the hour, they aren’t too keen on taking time to learn this new technique. The fewer that learn it, the fewer that are available to teach it, and the cycle continues…
As I’m building solo, I have none of these issues. I designed the house myself from the very beginning with advanced framing in mind. Thanks to my mentor, who introduced me to advanced framing, I’ve never built any other way. I’m saving time, money, and materials. If you really want to save sustainably, advanced framing is the way to go.
Framing the interior walls
Advanced framing will help me lower my heating bill by creating more space for insulation. However, insulating a house is just one of the ways to reduce the amount of energy needed to heat (or cool) a house. No matter how much insulation I put in the house, if I don’t control the air that is allowed to flow through the walls, it will be impossible to control the temperature.
According to the U.S. Department of Energy, up to 30% of heating and cooling costs is due to lack of air sealing. One of the places where air can escape is in the tiny gap between the sill plates of the walls and the concrete foundation. While I did place sill gasket in that area, that was only to prevent water from wicking up the concrete and into the walls. The sill gasket is air-permeable, meaning air can pass through it. I needed to add an additional layer that was air-impermeable.
The best time to do that work is now. After I frame the interior walls it will be nearly impossible to caulk the spaces where they connect to the exteriors.
I also will be using a continuous layer of drywall to control air movement. This means that the drywall will slide in behind the wall framing for the interior partitions, resulting in fewer joints in the drywall and thus fewer opportunities for air infiltration (see Image #5 below). Drywall is installed later. For now, I cut small scrap pieces of 3/4-inch material and used them as spacers to ensure the gap was sufficient.
I used standard framing instead of advanced framing for the interior walls since they don’t require any extra room for insulation. This meant spacing the studs at 16 inches on center instead of 24 inches, and capping the studs with a double top plate instead of a single. Additionally, I used 2x4s to frame most of the interior walls instead of 2x6s. (An exception is walls that house large drain lines and vent pipes.)
Plumb and line the walls
With all of the first floor walls complete, it was neat to be able to navigate the rooms and get an idea of the feel of the dimensions of the house. Before moving on to the second floor, I needed to take some time to ensure that all of my framing so far is straight, level, square, plumb, and true. The subfloor on the second floor will tie everything together, so this was my last chance to make sure it was just right.
I started by double checking the lengths of the top and bottom plates and the lengths of the corner studs. Next, I used a plumb bob to ensure each of the corners was plumb. I used long 2x4s nailed diagonally and nail stakes in the ground to push or pull the end of each wall as needed to plumb the ends of the wall. I knew the foundation was level, so since the wall lengths were equal and plumb, I knew the walls were square and true as well.
To check the middle of the walls, I nailed a 2×4 block to the top corner on each end of the wall and stretched a string tightly between them. Using a third block, I checked all along the wall to ensure this block fit snugly between the wall and the string. Where necessary I used additional bracing to make the wall straight.
With the exterior walls (hopefully) perfect, it was time for the interior walls. I used a powder-actuated hammer tool to nail the bottom plates of the interior walls into place (see Image #6 below). This tool uses a .22-caliber explosive to drive the nail into the hard concrete.
With this crucial step of straightening done, I was now confident enough to get going on the joists.