All window first floor in part 9 of NBC 1

[canwesteng]

Looking at the standard designs they are proposing here

https://www2.gov.bc.ca/assets/gov/f...-standards/guides/bc_std_des_catalogue_v1.pdf

for the province of BC.

I'm not sure how you can have an all window first floor and meet the braced wall requirements of part 9. So are all of these houses going to require an engineer? Not really work related just curious about what others think of this.

And I also don't like how many options have butterfly roofs. Seems like a disaster waiting to happen with your typical residential contractor. Not to mention the end result seems pricey per sf as well.

 

[TLHS]

The design assumptions say that they're designed using Part 9, but I also don't understand how that works.

Even if you could squeeze it into code somehow, it seems like a really bad idea to put something in place that supports building large parts of housing with a soft bottom floor where a bunch of the population is in very high seismic zones.

The fact that this doesn't say anything about the exposure conditions or limits on seismic, wind or snow loads makes me think that this is just high level architectural approvals, which seems like it doesn't solve the problem they're trying to solve. I assumed this was going to be full construction packages for buildings, but I haven't seen reference to more detailed documents anywhere.

You've got a three wall system on the bottom floor and your stair cutout right up next to one of the other walls when you're trying to do your three wall diaphragm detailing on these.

Then you've got stuff like Duplex 3 where the two duplex units are offset and they each have a full window wall, but then the common wall has about 30 percent overlap with the rest being windows. So the only shear wall you have for both units in the north/south direction is about 30% of the shared common wall with wonky irregular diaphragms through the whole thing.

If you want it reasonable and easy to approve why are these not all rectangles with conventional framing?

 

[dik]

Bad examples...

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[STpipe]

So are all of these houses going to require an engineer?

I mean, that's not necessarily a bad thing...

 

[dik]

Part 9 of the Code should not require an engineer; maybe not such good examples, in particular in Seismic areas.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[canwesteng]

Sure, in a perfect world an engineer could be involved, but that isn't the reality in NA. This seems like a good amount of money has been spent on plans that don't have the info needed for construction and basically can't be built without a ton of other consulting fees, for what are what if we're being honest very expensive designs to begin with.

 

[Eng16080]

If their goal was to provide simple, cost-effective housing, I'd say they've failed. With all those windows, I don't see how this works structurally without either a steel moment frame in that wall or designing it as a 3-sided diaphragm. Either way, to do it right, you have additional engineering and construction costs.

I'd say remove a third of those windows or whatever it takes to make a reasonable shear wall work. Then you have a cost-effective design.

Either they didn't consult a structural engineer on this, or they did and the engineer is looking forward to some future work.

 

[skeletron]

These look more like drawings to get you through the Development Permit phase which, in my experience, tends to drag on for various reasons. That is where they have 'simplified' the design:
-stairs are laid out
-heights are defined
-FSR is defined
-setbacks are defined
-exits are defined
They probably also have maxed out windows and energy requirements. I would expect that a client would still need to hide an architect, or house designer, to dial in the specific details for the submission. But this gets them in the fast-track stream at the very least (e.g. you can take the standardized design and it'll be X months, or you can start from scratch and it'll be X+9 months).

Based on my own experience, even if this is a Part 9 or not the AHJ will require a Sched B/C-B from the structural engineer...so, if the engineer is doing things by the book this means that structural drawings should also be produced. Part 9 structural design *doesn't really exist* in the Lower Mainland and there are so many mistakes in the new version of it that it really should be avoided.

I share the same concerns as most above. These units have given little thought to simple engineered design. 3-sided diaphragms, big open first floors, etc. would make for some changes in my design phase. That being said, there are firms out there that do a metric tonne of cookie cutter residential work and surprisingly don't give 2 hoots about lateral design. The builder will get the same 4-page drawing set with generic details.

 

[canwesteng]

Yeah I don't touch residential at all, I'm just curious more than anything. I did a little bit back when I was in SK just moonlighting, that was a mix of part 9 and engineered components

 

[EngDM]

Simpson is/has developed a "Strong-Wall" portal frame system, and have a big office in BC. I'm sure they'd love to get in on this.

I've never used this product, but at a glance it looks like it could maybe apply (I don't think they have CSA/NBCC tables yet), unless there are some dimension requirements or the loads end up just being too high.

I agree with the others though, Part 9 without an engineer reviewing the plans is a pipe dream with that entire wall being a window.