Designing As-Built Foundation Sill - Foundation Ladder?

[Asclepiadae]

Hey all,

 

I'm a homeowner (commercial electrician and Biomed, so some familiarity with Autodesk / CAD products... but just enough to be dangerous) and trying to build a digital twin for my home from the architectural drawings. One of the features we have is a "foundation ladder": a dual 2x4 rebate in the concrete which, with a quick bit of searching, I was able to figure out is fairly unique to western Canada (I'm in Edmonton).

 

 

For the top 3.5" of the foundation wall the width is reduced from 8" to 5" to place 2x4s (one inside and one outside) that the vapour barrier and then OSB ladder cap (essentially the sill plate) and insulated rim board then sits upon.

 

I just have no idea how to get CA to build this. I've poked around in the sill plate options, wall coverings don't seem to have a thickness option

 

Also a little stuck on how to define the OSB ladder cap and insulated Rim board in the sill plate options. Under the Sill Plate Framing Member Defaults, I don't see an option for OSB (although PSL is close... and unsure about Eng. Lumber option.) But then the rim board is also ... part of the sill in a way? It's certainly part of the basement as the joists/beams for the main floor are at that same level (inside the basement ceiling) sitting on top of the foundation wall, and then the OSB flooring is laid down on top.

 

Any thoughts on how to best approach this would be appreciated!

[SHCanada2]

I just specify the ladder in the details like above, and I ignore it everywhere else. BTW it is typically specified as pressure treated, same with sill plate(although I've never understood the purpose of a sill plate if you have a ladder, maybe to avoid a sill sealer or PT bottom plate on the knee wall side, although in your case there is a sill sealer).

 

If I had to I would do the same with the insulated rim board(shown in details only) and specify the width of the rimboard per the spec above

 

The sill plate is part of the basement (many arguments on this one)

 

It is specified as part of the wall but doesnt look like you can get it below 1". others may chime in here

 

Edited Sunday at 04:05 AM by SHCanada2

[Gawdzira]

Holy overkill Batman

[SHCanada2]

1 hour ago, robdyck said:

That would be for code compliance. Recent versions of the building code were changed to specifically mention the requirement for a sill plate with anchor bolts to provide lateral support for the top of foundation walls

hmm, I thought the AB edition, which explicitly has the ladder, precluded a requirement for anchor bolts unless in high wind.

 

or is everywhere high wind these days?

 

1) Except as required by Sentence 9.23.6.3.(1), building frames shall be anchored to the foundation unless a structural analysis that considers wind and earthquake loads and lateral earth pressures shows that anchorage is not required. 2) Except as provided in Sentences (3) to (6), anchorage shall be provided by a) embedding the ends of the first floor joists in concrete, b) fastening the sill plate to the foundation with not less than 12.7 mm diam anchor bolts spaced not more than 2.4 m o.c., or c) embedding in concrete two 38 mm by 89 mm sill plates, placed on edge and separated by blocking spaced 1.2 m o.c. 3) For buildings with 2 or more floors supported by frame walls that are in areas where the seismic spectral acceleration, Sa(0.2), is not greater than 0.70 or the 1-in-50 hourly wind pressure (HWP) is equal to or greater than 0.80 kPa but not greater than

 

 

Edited Sunday at 04:33 PM by SHCanada2

[SHCanada2]

1 hour ago, robdyck said:

That would be for code compliance. Recent versions of the building code were changed to specifically mention the requirement for a sill plate with anchor bolts to provide lateral support for the top of foundation walls. 

and do you know where this convention for the "ladder cap"/ OSB sill plate came from? I don't see it anywhere in the code, and the code requires a minimum nailing into a sill plate, so it cannot even be considered a real sill plate

[SHCanada2]

11 hours ago, robdyck said:

9.15 needs to be considered as well. 

9.15 has the max height and backfill, and states that an anchor bolt to the "floor system" is required for exterior grade > 4ft above slab.

 

But his "ladder cap" can't be seriously considered as the anchored sill plate(and by code can't be one as there is a required nailing pattern into the sill plate), which means then every house in alberta with > 4ft of exterior backfill, needs a normal 2X4/6 sill plate with anchor bolts?

 

Edited Monday at 03:56 AM by SHCanada2

[SHCanada2]

interesting, nothing to do with uplift, only lateral support for the foundation walls. And that section has been around since at least 2006

 

next time I drive by a house being framed I will take a look.