Fire separation in SFD suite

[Mac Moonfire]

Hi,
I have a reno consisting in adding a residential suite in a single family dwelling.
The goal is to achieve a 45min fire resistance rating on an existing 2x4 wood stud wall 16"o.c. regular 1/2" drywall on the house side and mineral wool between studs.

I know those 2 things:

• 30 min fire resistance rating for walls one layer of 1/2’’ regular drywall on each side of the wall is required
  
• 45 min fire resistance rating for walls one layer of 1/2’’ Type X drywall on each side of the wall is required

My questions:

1. could the addition of 2 layers of 5/8" type-X on the suite side achieve the 45min?
2. could the addition of 2 layers of 1/2" type-X on the suite side achieve the 45min?
3. Does the mineral wool change anything at all?
4. How can I calculate that? Where exactly can I find the information?

I'm using the BCBC2018
Thank you

 

[cda]

Your talking Canadian, right?

They do not like to put the building code online

From IBC look at maybe

table 722.2.1.4(2)

If not there somewhere in that area

https://codes.iccsafe.org/content/I...smoke-protection-features#IBC2015_Ch07_Sec722

 

[classicT]

Fire resistance ratings are determined by exposure to both sides. Addition of GWB to one side will not get you there. Once the studs burn out, the GWB falls.

 

[cda]

Does that apply

Fire resistance ratings are determined by exposure to both sides. Addition of GWB to one side will not get you there. Once the studs burn out, the GWB falls.

Ok in a single family house, are they looking more at time, versus a true tested assembly? with drywall on both sides?

 

[classicT]

Does that apply





Ok in a single family house, are they looking more at time, versus a true tested assembly? with drywall on both sides?

Yes. Otherwise if the fire happens on the unprotected wall side, the wall fails in about 20-30 minutes, not the 1 or 2-hrs that is intended.

 

[Mac Moonfire]

Yeah, Canadian eh!
The BCBC2018 and all others are now free online https://www.bcpublications.ca/BCPublications/

Thank you for the answers, it solved my current reno. I will be reading more on fire separation for future similar situations.
thank you again!

 

[Mac Moonfire]

To nicely tie this thread, here's what I have found for Fire separation in Wall roof assemblies of residential occupancy for BCBC2018.

9.10.3.1. Fire-resistance and fire-protection ratings:
1) Where a fire-resistance rating or a fire-protection rating is required in this Section for an element of a building,
such rating shall be determined in conformance with

a) the test methods described in Part 3,
b) the calculation method presented in Appendix D, or
c) the construction specifications presented in Tables 9.10.3.1.-A and 9.10.3.1.-B.
​

Tables 9.10.3.1.-A (for walls) and 9.10.3.1.-B (for ceiling and roofs) are most straight forward. They are found in Division B - Fire and Sound Resistance Tables
Cheers,