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Basic Wall Framing (2): Sheathing Framed Walls

March 21, 2019

Snap a line, put the panel on the line and nail it, tape the seams, and where to snap that line in the first place.

In the previous episode, we were going over basic wall framing as part of a double stud wall home in Portland, Maine.

We were cutting plates, nailing studs, stacking walls, and snapping lines. Where to snap the line, is where we begin this episode.

The wall sheathing should extend below the rim joist, which is inset on this house to allow for a continuous band of insulation. The wall sheathing below dictates the overhang.

It’s about 9 inches in this case, and Ben subtracts a quarter inch to allow for inconsistencies.

Aligning the bottom of the plate with his overhang number, 8-3/4, he marks 48 on the stud, and they snap the line. When snapping long lines like this one, it is best to break the line in the center and snap it as two lines. This cuts string vibration in half, which makes the chalk line half as fat and twice as accurate.

Four wall sheathing tips

Now, they pull sheets from the pile and nail ‘em, to wood. If you laid out the wall right, the edges will break on studs.

  1. Nail the corners with hand nails so that the crew can keep placing sheets. When the first row down, on the line, and perfectly gapped, it can be nailed off with a gun nailer.
  2. Uses an eight-penny nail to gap sheets 1/16 inch apart.
  3. When piecing in the ends, put the cut edge toward the outer edge of the wall, to keep the gaps neat.
  4. Stagger the second row four feet from the first row to improve racking strength.

After the wall is nailed off, Liz knocks home the under-achievers and then dabs each nail head with a spot of ZIP’s liquid flashing. This is not required or specified by the manufacturer, it is just something they like to do to prove how detail-oriented they are.

If you're going to do something, do it efficiently

Notice the efficiency of motion and forethought here.

The clean corner makes contact with the sheathing to act as a pivot point so Liz can cleanly and quickly smooth the liquid flashing to seal the nail holes against possible water penetration. It keeps the squeegee as clean as possible with no wasted movement.

Also, notice that the flashing gun is placed with the tube's nozzle above a nail so that anything that may dribble out will accomplish work.

One more thing: the official word is that the nail polish was NOT chosen to match the liquid flashing, it was just a happy accident.

Taping sequence for wall sheathing

Sealing the nail heads is not required, but sealing the seams between sheets is and there is a process for that.

  • First, the tape should always overlap shingle-style, so lower vertical seams should be done first.
  • Next, the horizontal band can be done, and finally the upper verticals.
  • Always use a roller or some other method to mash the tape into the substrate. It helps the viscoelastic adhesive to wet out into the substrate’s irregular surface.

We’ll go into more detail about exterior air and water management is a different episode of this series, because now, it is time to stand the wall. But let’s do that next time.

—This is the second part of a seven or eight-part series on framing, flashing, and sealing a double-wall house.

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