foamed plastic sheathing vs foamed plastic outboard

[sunyaer]

This is from Ontario building code SB-3

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Table 1 (Cont’d)
Fire and Sound Resistance of Walls(1)

EW1a
EW1 with
15.9 mm Type X gypsum board(7)(11)
exterior sheathing and cladding(12)

(12) Includes any exterior wall sheathing and cladding combination allowed under Part 9 other than foamed plastic sheathing. The
cladding portion can include foamed plastic outboard of noncombustible, structural wood-based or gypsum-based sheathing
conforming to the minimum thicknesses listed in Table 9.23.16.2.A. of Division B of the Building Code.
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(12) is a note under Table 1.

Question a): The first part of the note states that "includes any exterior wall sheathing and cladding combination allowed under Part 9 other than foamed plastic sheathing", can this be understood as "foamed plastic sheathing" can not be used as exterior wall sheathing?

Question b): What kind of product is foamed plastic outboard in "the cladding portion can include foamed plastic outboard of noncombustible? Is it rigid insulation board? Does "outboard" mean boards that are used as exterior wall sheathing?

Question c): Do "foamed plastic sheathing" and "foamed plastic outboard" mean the same things or totally different things?

 

[e hilton]

You're reading it wrong. "Eats shoots leaves"

foamed plastic outboard of noncombustible, structural wood-based or gypsum-based sheathing means a layer of foamed plastic on the outboard side of gypsum sheathing.

 

[sunyaer]

You're reading it wrong. "Eats shoots leaves"

foamed plastic outboard of noncombustible, structural wood-based or gypsum-based sheathing means a layer of foamed plastic on the outboard side of gypsum sheathing.

That makes sense.

Are "noncombustible", "structural wood-based" and "gypsum-based" parallel, meaning three types of sheathings?

 

[tmurray]

(a) Yes.
(b) Outboard refers to insulation that is on the outside of building sheathing. At one point sheathing was typically boards, so anything "outboard" was any product that was outside of this (siding). Rigid foam would be a good example, provided it is placed after any required sheathing.
(c) Foamed plastic sheathing integrates a foam insulation with the sheathing into a single product.

Are "noncombustible", "structural wood-based" and "gypsum-based" parallel, meaning three types of sheathings?

Yes, the clause is indicating that all three are acceptable options that can be used individually.