I am building a workshop and I have 7 vertical feet to sheathe to reach the tip of the roof. I have 4x8 sheets but they're too heavy for me to lift to the top by myself. I'm considering cutting them in half so it would be one 4 foot section and then a 3 foot section on top of that. Are there any severe disadvantages to doing this?

  • Hello, and welcome to Home Improvement. Where in the structure would these boards be? (A diagram or picture would be really helpful.) Feb 14, 2019 at 17:36
  • I don't have a pic, but I'll try to explain the best I can. The wall is 16 feet wide and ~10 feet tall. On top of the 10 foot wall is the roof which is about a 7/12 pitch (top of the rafters are cut at 30 degrees). I put sheathing along the bottom so there is 4x8 feet OSB placed vertically about 7 inches off the ground (bottom of the wall rests on 8in high concrete blocks). So the top of the sheathing right now is ~9ft high. I need to extend the sheathing for the top 'half' of the wall which is about another 7 ft.
    – DaveK
    Feb 14, 2019 at 17:55
  • Isn't Z-flashing usually used in a horizontal joint where the 4x8 sheets are placed with the seams running vertically, i.e., the 8 ft sides vertical? Feb 14, 2019 at 19:32
  • Maybe I have missed something but I was taught to z flash at horizontal seams and they will require a nailer to be installed a lot of extra work where a 2nd person helping could save time and cost.
    – Ed Beal
    Feb 14, 2019 at 19:43
  • Flashing is not commonly installed there in residential construction. Housewrap serves that purpose. Water should never reach the sheathing anyway.
    – isherwood
    Feb 14, 2019 at 20:00

2 Answers 2


Structurally it doesn’t matter.

The Building Code allows for “Blocked” and “Unblocked” wall sheathing. The shape of the installed sheathing is not important, as long as they are not scraps less than 4 square feet.

Unblocked sheathing is common. Blocked sheathing is for extreme loads and unusual loading, (i.e.: lots of windows in a row with just a couple of feet of wall near a corner, etc.)


It's very common to need to splice wall sheathing in the open, but you usually need to float blocking to secure the joint.

Cut a pile of 2x4 blocks at 22-1/4" (slightly less than the 22-1/2" that you'd see in a perfect world). Work along the wall and staple (or nail or screw) them in place to the existing sheathing, then continue upward.

Rather than cutting your sheets in half, though, see if you can tilt them into place at full height. It may help to drive some 16d nails halfway in under the bottom wall plate to act as temporary supports (I don't like to see sheathing lap onto concrete--technically it shouldn't be in contact). Or hire a neighborhood kid to lend some muscle. You'll save a ton of work.

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