3'rd story addition on an old Victorian home

[lubos1984]

Hi Everyone,

I'm working on a 3'rd story addition to a current 2 and a half story (there is already a 3'rd floor in the front half of the house). The project is to renovate the existing 3'rd floor and add the rear addition. The client wants to leave the front dormer in place (heritage)
The work seems simple enough except that I'm dealing with a double brick structural wall and don't have much experience in these kind of walls.
The current 3'rd floor sits on 2x6 floor joists utilizing interior load bearing wall. The plan is to avoid removing these so as not to disturb the 2'nd floor ceiling. 12" TJIs would instead be installed spanning exterior wall to exterior wall and be embeded into the brick just like the existing 2x6 floor joists. Is there any special care consideration that needs to be taken when embedding new joists into these kind of walls. The client wants to preserve as much of the exterior brick as possible (again heritage)

Thank you for all your help!

 

[XR250]

I would not embed TJI's in anything! Better to bolt a band to the wall and hang the joists. Address the out-of-plane wall loads as needed.

 

[lubos1984]

Thanks XR.
I think I will build the new floor above the existing with a ledger board around and secure TJIs to the ledger board. As far as securing the ledger board I was thinking using anchors with epoxy and treating it as a masonry connection. Is there any special consideration in securing the ledger board to a double wall structural brick ?
Thanks for your help!

 

[XR250]

I would check Hilti's website. How are you going address lateral stability? Looks like your first story is pretty soft.

 

[lubos1984]

the existing 3'rd floor floor joist and the existing 2'nd floor roof joist are embedded into the brick wall so that should be sufficient for lateral support.
idea to go up as shown below.

 

[kipfoot]

I try to avoid that ledger detail for floor loads on double wythe existing brick walls, unless you're absolutely sure that the existing brick and mortar is in excellent condition. Which, judging on the photo, yours doesn't seem to be. Parapets are notorious for being in poor condition due to weathering from both sides, and you'd be adding an eccentric load.

I'd vote in favor of a detail that places the load near the center of the masonry wall. I suggest pockets at 4' to 6' to support trimmer joists, with headers in between. Infill joists would be supported from hangers from the header.

 

[lubos1984]

Could I not utilize the existing ceiling joists in that way ? Like add a flat 2x6 at existing joist edge, have a ledger board above and then span TJIs across the entire length. The existing joist would take the load and of course would need to be checked. This would avoid making more pockets in the wall and the ledger would be secured to wall just for lateral support ? Any thoughts ?

 

[lubos1984]

Would need to add blocking below the flat 2x6 as well