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Community and Q&A

Screwing Vertical and Horizontal Furring

shedworkshop | Posted in General Questions on

When screwing a wall assembly with vertical and horizontal furring, should the screws for the outer furring layer go all the way to the studs?

Wall assembly plan:

– R15 rockwool cavity insulation
– 2×4″ Stud
– 15/32″ Sheathing
– 0.5″ R2.5 XPS board
– 1×3″ vertical furring
– 1×3″ horizontal furring
48″x10′ fiber cement siding (Hardie)
– 2.5″x10′ fiber cement battens (Hardie)

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  1. Expert Member
    BILL WICHERS | | #1

    What climate zone are you in? R2.5 exterior rigid foam on an R15 wall seems awfully light. BE SURE you follow the tables as a minimum to ensure you have a safe wall assembly.

    Rergarding the furring, I would try to hit the studs from the outermost furring layer since you're planning to hang a lot of weight from it. It's always safer/stronger to screw into studs than into "thin stuff".

    I would also consider using ripped strips of 3/4" plywood instead of 1x3s since plywood is far less prone to splitting.


    1. shedworkshop | | #3

      Climate zone 4a. I'm trying to find a table for the recommended ratio of exterior/interior insulation, but can only find ones for 4c (marine). Would using R5 or R10 be better to protect against potential condensation? It's only for a shed / workshop (hence the username).

      I'll look into using ripped 3/4" as well.

  2. Expert Member


    I would just tack the vertical furring with a brad nailer, and screw or use a framing nailer through both when you put up the horizontal layer.

    1. shedworkshop | | #4

      Sounds like a good way to keep it sturdy and avoid using too many screws. Thanks Malcolm!

  3. CurryWarbler | | #5

    I plan on a similar assembly in Marine 4C zone: gypsum/cellulose/ply/WRB/1” rockwool/vertical furring/horizontal furring/vertical cedar siding.

    Same question essentially - can the siding be attached to the outer horizontal furring strip only….or do these need to go directly into blocking/studs. And finally, does the siding itself need to also penetrate to the stud, or is the furring sufficient at either 12” or 16”OC?

    Thank you in advance!

    1. Expert Member
      MALCOLM TAYLOR | | #6


      You are fine just attaching the siding to the outer furring. The exception to that are some proprietary brands of siding - mainly cement based or composites - which have their own installation requirements, and sometime want more that 3/4" backing.

      1. CurryWarbler | | #7

        Thank you Malcolm!

        Just to clarify, in this case using vertical cedar, would you maintain that the outer horizontal furring be secured to the studs/blocking as well, or is it sufficient in practice to have those only affixed to the vertical furring strips?

        Thank you again.

        1. Expert Member
          MALCOLM TAYLOR | | #8


          My own preference would be to tack the vertical furring just enough to keep it in place, and use a single screw through both it and the horizontal one into the framing to secure everything.

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