Architekwiki
  • Home
  • WIKI
  • Start Here
  • Resources
  • Other
    • Reading List
    • Ochre >
      • Ochre
      • Ochre KB
      • Ochre FAQs
      • Ochre Help
    • Details
    • The 3 Aspects
    • About
    • Subscription FAQs
    • Terms of Use
  • Subscribe
  • Home
  • WIKI
  • Start Here
  • Resources
  • Other
    • Reading List
    • Ochre >
      • Ochre
      • Ochre KB
      • Ochre FAQs
      • Ochre Help
    • Details
    • The 3 Aspects
    • About
    • Subscription FAQs
    • Terms of Use
  • Subscribe

Architekwiki

A Resource For Architects
Click here to get good stuff in your inbox

Firewalls

6/13/2013

 
Separating an existing building from a new addition by a firewall always (it seems) has unanticipated consequences. This refers to a true firewall rather than a fire separation wall. No matter how hard you try, there is always a surprise waiting for you. 

Technically a firewall must be able to remain standing after the collapse of the structure on either side. This means that the wall cannot help support that structure. A favored way around this is to use two walls, each supporting the structure that is on its side. This approach triggers the need for two fire doors at each opening, one in each wall. Two doors creates all kind of collateral issues, and usually results in a vestibule to separate the doors, which in turn is fire-rated construction.

The alternative is to use a free-standing firewall, which is basically a cantilevered wall anchored in its footing. Engineers tend to over-react to this situation. Maybe they should. 

The two drawings below show how complicated the situation can become. Click the images to download a PDF for easier viewing; or download Plans here and Sections here.
Firewall Plan
Firewall Sections
We used single, self-supporting firewalls where we had to pass through the firewall. Elsewhere we resorted to the double-wall solution to avoid the underpinning required by the single wall.

The problem with a single wall that is braced by the construction on each side is that a collapsing building creates a wind load on the wall. There are ways to anchor the wall to resist the wind load; and there are ways to let the structure fall away. There just aren't any good ways of doing both on both sides of the same firewall. If your code official knows this, ...
Matt Duggan
11/3/2020 06:26:32 pm

Thanks for the information. I was hoping to do the double firewall, but need to egress through it which seems to require a single wall. I don't see a way to do a "vestibule" between the two walls

Rick Wolnitzek
11/3/2020 07:24:35 pm

Matt, when I have done a vestibule, I made a projecting ’box’ of masonry walls with a lid/roof made of precast concrete lintels in one the walls to make the vestibule. If means of egress could be either way through the firewall you will need a pair of doors where one leaf swings one way and the other swings the opposite way. It’s a special frame.
Hope this helps.

Matt Duggan
11/3/2020 07:34:26 pm

It does help. Basically, same conclusion. don't egress through a double wall. I did find this on another website: “there is another solution for the double fire wall that would eliminate having double doors. It is not specifically addressed in the code or even NFPA 221, Standard for High Challenge Fire Walls, Fire Walls, and Fire Barrier Walls, but I have done this in the City of Phoenix and it was accepted. The door can be a single fire door supported by a structural frame that is independent of each wall and has its own footings. The joints between the frame and the two walls are protected using a joint firestopping system.”
https://www.thebuildingcodeforum.com/forum/threads/fire-separation-b-w-adjoining-buildings-with-joint-service-doorways.24524/#post-191273


Comments are closed.
    Resources

    Start Here

    YouTube Channel

    Join The Mailing List

    Picture

    Terms of Use
    Your use of Architekwiki is implicit agreement with the 
    ​
    Terms of Use.
    Thank You for your donation

    x
    Get Good Stuff in Your Inbox
    Picture
    Subscribe

    RSS Feed


    Archives

    January 2023
    November 2022
    October 2022
    July 2022
    June 2022
    April 2022
    October 2021
    September 2021
    August 2021
    June 2021
    May 2021
    February 2021
    January 2021
    December 2020
    November 2020
    October 2020
    September 2020
    August 2020
    July 2020
    June 2020
    April 2020
    March 2020
    February 2020
    January 2020
    December 2019
    November 2019
    October 2019
    September 2019
    August 2019
    July 2019
    June 2019
    May 2019
    April 2019
    March 2019
    February 2019
    January 2019
    December 2018
    November 2018
    October 2018
    September 2018
    August 2018
    July 2018
    June 2018
    May 2018
    April 2018
    March 2018
    February 2018
    January 2018
    December 2017
    November 2017
    October 2017
    September 2017
    August 2017
    July 2017
    June 2017
    May 2017
    April 2017
    March 2017
    February 2017
    January 2017
    December 2016
    November 2016
    October 2016
    September 2016
    August 2016
    July 2016
    June 2016
    May 2016
    April 2016
    March 2016
    February 2016
    January 2016
    December 2015
    November 2015
    October 2015
    September 2015
    August 2015
    July 2015
    June 2015
    May 2015
    April 2015
    March 2015
    February 2015
    January 2015
    December 2014
    November 2014
    October 2014
    September 2014
    August 2014
    July 2014
    June 2014
    May 2014
    April 2014
    March 2014
    February 2014
    January 2014
    December 2013
    November 2013
    October 2013
    September 2013
    August 2013
    July 2013
    June 2013
    May 2013
    April 2013
    March 2013
    February 2013
    January 2013
    December 2012
    November 2012
    October 2012

    Categories

    All
    Business Development
    Business Management
    Design
    Detail
    Miscellaneous
    Project Management
    Resources

Picture

Picture
VISIT ARCHITEKWIKI'S RESOURCES
​
START HERE
ABOUT
SIGN UP
TERMS OF USE
Architekwiki | Architect's Resource | Greater Cincinnati 
© 2012-2022   Architekwiki​