holdowns

[sunsen 0]

I have a question for an architect out there who is familiar with CA building codes. I'm planning using concrete block for the exterior walls of a house. I'm figuring on digging some footings, building the exterior walls, then pouring 4" of concrete for interior floors. What I'm wondering about is interior walls. Should I be planning on footings underneath all the interior walls? If so, is it typical to place threaded rod in those footings that will extended up through the slab in order to anchor the interior walls. I'm sure some of those walls will be structural when it comes to the roof. I've built structural slabs before, which would resolve the issue, but in this instance I don't want the elevation gain. 

 

Thanks,

 

Tom

[Doug_N 62]

I am from Canada, and this question here would be addressed to a structural engineer, not an architect.  

[sunsen 0]

Okay. Are there any structural engineers, and/or architects, on this forum who know the answer to my question? 

 

 

[TheKitchenAbode 578]

As a general rule you would only need footings for interior walls that are loadbearing. Just curious as to why you would be building, I assume a house, in Canada on a grade level slab, most Canadian homes are built with full height basements.

[sunsen 0]

I'm building in California, on the side of a mountain. I suppose the abbreviation CA could mean Canada as well, although I wasn't aware of that. 

 

So when you put a footing under a load bearing interior wall, do you preset threaded rod in the footings so they can grab the bottom plate that sits on the slab? I'm thinking the footings would be below the slab, which would be done in a monolithic pour, for convenience sake. I know we're not allowed to wet set foundation bolts but I've never seen what I'm talking about done before. 

[TheKitchenAbode 578]

10 minutes ago, sunsen said:

I'm building in California, on the side of a mountain. I suppose the abbreviation CA could mean Canada as well, although I wasn't aware of that. 

 

 

Sorry, my mistake. Best to discuss this with someone familiar with this type of construction in California.

[sunsen 0]

No worries. I know Richard Morrison does his own calculations and gets on here from time to time so perhaps he'd know. Thanks anyway. 

 

[DRAWZILLA 784]

24 minutes ago, sunsen said:

I know we're not allowed to wet set foundation bolts but I've never seen what I'm talking about done before. 

I'm in California and we wet set anchors on every job. you really should wet set all holdowns bolts also, although you can drill them in after, You will need a special inspection with each hole you drill --costly.

[sunsen 0]

Wet set means sticking the holdowns in position as you pour. We used to do this out on Maui. In CA holdowns have to be secured in place prior to pouring. Foundation bolts as well. Much better practice. 

 

[DRAWZILLA 784]

1 minute ago, sunsen said:

Wet set means sticking the holdowns in position as you pour. Holdowns have to be secured in place prior to pouring. Foundation bolts as well. 

 

Didn't you say you couldn't wet set in your post?

[sunsen 0]

Yes, we are not allowed to wet set foundation bolts or holdowns in the silicon valley area or any of northern CA that I'm aware of. 

[ToolBox 1]

It sounds to me that you first need a plan including architectural design, structural design, energy compliance etc.

Once those decisions are made, then you will know where your bearing walls and shear walls are.  This will determine all your footings and hold downs.

All hold downs and anchor bolts in California, must be in place for the pour.  It does make finishing more difficult.

As said above you can drill and epoxy threaded rod after with a special inspection.  You could also check out Simpson titan bolts for wood plates. 

I am curious, why you are using CMU's?  How do you plan on achieving  your insulation values?

 

[Richard_Morrison 447]

Hi Tom,

 

Just saw this. I'm not here as often as I used to be. But, some general thoughts are below.

First, for interior slabs, I certainly wouldn't use less than 5" and 6" would be better. 4" is a pretty chintzy garage slab, and likely to crack. I'd use #3 rebar, say at 12" E.W., rather than WWF. If walls are not loadbearlng or designed for shear, they don't need thickened footings beneath them, and don't need preset anchors or drilled expansion bolts. Powder-driven pins would be the typical way to secure these to the slab. In a nutshell, I highly recommend getting your structure fully engineered based on actual soil conditions and local seismic/wind values. HTH...