I may be wrong on flanking!

[kiwijbob]

So recently I've been in debate with a small residential developer on flanking paths through wood stud party walls at the 2nd floor level for Part 9, 2 storey row houses, I was (and am) of the opinion that 9.11.1.4 (4) (b) means that there must be a break in the continuity to the flanking path but it's been put to me that as long as the "joists or trusses that are not continuous across the junction" then his proposed single stud partition is ok. I've been pushing for the double stud wall as per below as I know this is a more robust acoustic detail..... Am I really wrong on this, is he correct to use his single stud wall that he "has used many times previously" and will the code support it? I usually remind people at this stage that the code is the bare minimum required not the maximum.

This is the detail that was being pushed on us c/w res channels either side of the studs & 2 layers of 5/8" type X


This is what we're pushing back with.

the whiskey has almost run out.....

 

[Yankee Chronicler]

Dunno about Canada, but that wouldn't fly for townhouses in the U.S.

 

[tmurray]

From a requirement standpoint, I feel it is important to delineate which assemblies are separating assemblies and which are adjoining construction (commonly called flanking assemblies) to ensure requirements are being properly applied. Separating assemblies provide a direct separation between units. Flanking assemblies interact with separating assemblies in a way that can convey noise between the units. In this case, the wall is a separating assembly and subject to requirements under 9.11.1.1. The floor joists are a flanking assembly and subject to requirements under 9.11.1.4.

The designer is correct that (4)(b) provides a compliant solution to discontinue the joist at the party wall. It does not appear to require the walls themselves to be distinct structural entities.

Another area of concern might be with the continuity of the fire rating of the party wall itself (per 9.10.11.2). Assuming this is distinct ownership townhomes, these walls must provide a continuous fire rating from the slab to the underside or roof sheathing. It is difficult to tell from the detail if this is being met.

 

[Inspector Gadget]

Another area of concern might be with the continuity of the fire rating of the party wall itself (per 9.10.11.2). Assuming this is distinct ownership townhomes, these walls must provide a continuous fire rating from the slab to the underside or roof sheathing. It is difficult to tell from the detail if this is being met.

^^^
This.
I see issues with these elements of designs in duplexes and townhouses more often than I'd like.

In fact, I now treat party walls on buildings with (a) basements or (b) multiple storeys the same way I treat exit shafts - I won't issue a permit until there are drawing details showing the correct connections showing continuity of the f/r drywall.

 

[SCBO1]

Does Canada codes use (UL) listed wall designs or gypsum wall board manufactures designs like (USG)?

In a row house in Canada, is it a property line and do they require a 2-hr or 1-hr separation. Probably to many variables in my question.

 

[Inspector Gadget]

Does Canada codes use (UL) listed wall designs or gypsum wall board manufactures designs like (USG)?

In a row house in Canada, is it a property line and do they require a 2-hr or 1-hr separation. Probably to many variables in my question.

We use two (or three) methods
a) ULC-listed assemblies
b) Assemblies that work under an additive part of our code called Appendix D
c) For some buildings, generic assemblies suitable for small buildings.

When it coms to row/townhouses and duplexes, the general principle under NBC is for a 45-minute fire sep for single-storey dwelling units on the same property;
1-hour fire separations for two-storey dwelling units on the same property;
1-hour *party walls* (from foundation to roof deck) when buildings are on separate properties.

 

[kiwijbob]

I would expect to see the rim board/joist protected with min 1 layer of 5/8" type X & 1 layer of 1/2" type X which will in effect mean for practical purposes 2 layers of 5/8" type X either side within the floor structure.