FordTruckWench
Well-known member
This is for a shed. Someday it may become "part" of the house, so I want to build it to full earthquake codes.
Earthquake holddowns require at least 3" x 3.5" material. It is acceptable to build this up by sistering two 2x4's. Earthquake shear wall sheathing needs its edges to bear a full 1.5" on the framing. Once again, this implies a minimum of sistered 2x4's at each plywood seam.
When using two sistered 2x4's at panel seams, this means that the sheathing seam will line up exactly with the 2x4 seam! This creates both a weak spot and an air infiltration spot. Therefore, I'm thinking of using 4x4's at all sheathing seams. However, it seems that standard practice may to simply double up 2x4's. Perhaps composite (built up) members are more stable than solid members because of multiple grain arrangements.
So, sistered 2x4's or single 4x4's?
A related consideration: I saw a video or read a website mentioning a new idea for earthquake framing. A 4x4 "block" should be installed between consecutive studs at the middle level of the wall. This is sort of like fire blocking, except that the purpose is to keep studs from twisting when a shear wall is racked. It would be easier to install these blocks if all studs are 2x4's, i.e. no toenailing required with a bit of planning ahead.
Earthquake holddowns require at least 3" x 3.5" material. It is acceptable to build this up by sistering two 2x4's. Earthquake shear wall sheathing needs its edges to bear a full 1.5" on the framing. Once again, this implies a minimum of sistered 2x4's at each plywood seam.
When using two sistered 2x4's at panel seams, this means that the sheathing seam will line up exactly with the 2x4 seam! This creates both a weak spot and an air infiltration spot. Therefore, I'm thinking of using 4x4's at all sheathing seams. However, it seems that standard practice may to simply double up 2x4's. Perhaps composite (built up) members are more stable than solid members because of multiple grain arrangements.
So, sistered 2x4's or single 4x4's?
A related consideration: I saw a video or read a website mentioning a new idea for earthquake framing. A 4x4 "block" should be installed between consecutive studs at the middle level of the wall. This is sort of like fire blocking, except that the purpose is to keep studs from twisting when a shear wall is racked. It would be easier to install these blocks if all studs are 2x4's, i.e. no toenailing required with a bit of planning ahead.