When building an exterior load bearing wall 12' high, using 2x6's, is there horizontal blocking/bracing required between the studs? If so, what are the requirements for that? ie. how many per cavity, do they stand on end or go flat, etc? IRC 2012.

4 Answers 4


If I remember right, any stud section that is over 10' tall needs blocking. Any place I have seen, has been in the center of the height, placed flat so it completely blocks the cavity. It is for fire stopping I believe, perhaps structural as well.


Besides the blocking it is often a worthwhile idea to add triangular bracing to external walls to keep them strong and straight. In the past this was often done by notching in a 1x4 into the face of the studs from the outside. These days there are much easier to install metal strappings you can install on the outside surface of the studs in an X cross formation. (The X cross format is important for strapping because it works well in length stretch resistance but not so well in length shrink (compressive).

This can have particular value in certain cases as follows:

  1. Local building code may require this as practice.
  2. Extra tall and wide walls may be built.
  3. The building is being constructed in an area where high winds are possible.
  4. The building is in a tornado zone.
  5. The building is in an earthquake zone.

Fire blocking is required in 1) horizontal and vertical framing spaces, like stud spaces and furred spaces at 10’, 2) intersection of walls and floors, 3) intersection of walls and attics, 4) top and bottom of stairs, and 5) at cornices. (See R302.11.)

You can use: 1) 2x solid wood, 2) 2 layers of 1x solid wood, 3) 23/32” (3/4”) plywood with joints backed up with 23/32” plywood, 4) 3/4” particleboard with joints backed up with 3/4” particleboard, 5) 1/2” gypsum board, 6) 1/4” cement based board, 7) batts or blankets of rock wool or fiberglass insulation secured in place in approved manner, and 8) cellulose insulation when installed in an approved manner. (See R302.11.1.)

  • 1
    Is there also a requirement for structural purposes, besides fire blocking?
    – Nick
    Commented Feb 21, 2018 at 4:27
  • Structurally: 1) studs must be continuous from sole plate to top plate, unless jack, trimmer or cripple at openings 2) must be No. 3 and better (hmmm...I was surprised about that too) unless in a non-bearing wall they can be “Utility”, 3) exterior walls must be designed to withstand minimum wind load for you area, 4) 2x6’s must. be laterally supported every 10’ ( sheathing or gyp. bd. satisfy this), 5) maximum spacing is 24” oc unless supporting 2 floors and a roof...then it’s 16” oc, 6) maximum height in non-bearing walls is 20’. (See Table R602.3(5))
    – Lee Sam
    Commented Feb 21, 2018 at 5:44
  • Energy Code for exterior walls: needs to be minimum 2x6 or you’ll need to have rigid board plus batt in 2x4 walls.
    – Lee Sam
    Commented Feb 21, 2018 at 5:47
  • Wall Sheathing: 1) maximum spacing of 16” for 3/8” and 1/2” plywood, 2) 16” for 1/2” OSB. Notching bearing walls cannot exceed 25% the width and 40% in non-load bearing walls. Drilling holes can’t be more than 60% the width if 5/8” is left on each side of hole. Also, you can use a single top plate, but it’s too complicated to explain. (R602.)
    – Lee Sam
    Commented Feb 21, 2018 at 6:11
  • My version of the IRC codebook (2012) says Horizontally at intervals not exceeding 10 feet and Vertically at the ceiling and floor levels in R302.11.1. If I'm reading that right, then the 10' intervals is only needed in horizontal spaces like joists, not in vertical spaces like 12' wall cavities, correct?
    – Nick
    Commented Feb 21, 2018 at 6:16

Often times with the OK from the building inspector I've been able to avoid all together, the time-consuming task of installing fire blocking, on an outside wall which is insulated, which can also act as a draft stop.

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