Garage Roof Truss Layout

[Bob1680]

Hello, My friends,

I have a one-story garage which is skewed to the 3 floor house. The house foundation and above-grade walls are all ICF walls. The garage is concrete strip footing with 2x6 wood stud walls. I'd like to ask for help on:
1. How should the garage foundation connect to the house foundation.
2. How should I layout the roof truss ? I've sketched 3 layouts showing on the drawing. See teh attachment. Please advise.

Your help is really appreciated.

 

[phamENG]

1. I would have them done monolithically. If you have a basement, then step the footing up to the higher elevation. The exact detail will depend on soil type and regional practices.
2. I'd let the truss manufacturer do it. For planning purposes, I wouldn't expect a girder truss. The truss profiles will change, but that's okay - with the girder your smaller trusses (not quite jacks?) would all be different lengths and heights anyway.

 

[jayrod12]

If you have frost issues, or generally just questionable soils, like I deal with where I am, we'll put the attached garage on spread-bore piles bearing at the same elevation as the house foundation. Otherwise we have seen too often where the garage and the house move differentially and rip away from each other.

I agree with Pham regarding pour sequence for the garage gradebeam/frost wall. However I could likely live with key and dowels in the house foundation wall to allow the garage to be poured at a later date.

Also agree with Pham regarding truss layout. I'd bet that Option 3 is where they'd end up wanting to go with it. Potentially option 2, but instead of rafters, I'd likely do all trusses but really you're just creating more pieces in that instance. So my vote is option 3. Make sure your ledger connection to the house wall is sound.

 

[phamENG]

Ha...there were three pages...oops. yeah. #3 is what I was describing...

 

[Bob1680]

The foundations are 5ft below grade, so the frost heave is not an issue. My concern is if there is a need for settlement joint between garage' concrete footing and house' ICF foundation. and How should I connect the garage's 2x6 wood stud wall to the house's ICF wall. Thanks.

 

[phamENG]

Only if you want the house and garage to settle independently - though I don't know why you would. I'd make them continuous between the garage and the house to minimize differential settlement. If it's enough of a concern, working with a geotech on a house that size would be prudent to estimate settlement between the two sections and work out foundation sizes that bring them somewhat in line with each other.

As for fastening the wood wallto the ICF wall, depending on loading I'd either spec long concrete fasteners that can get through the insulation and attach to the concrete core or I'd have them cut out a section of insulation and fasten directly to the concrete with Tapcons or other proprietary fastener. PAFs with washers designed for wood could also be an option.

 

[jayrod12]

The ICF-VL connectors from Simpson strongtie may give you a fairly robust connection between the wood framing and teh ICF. I know they're generally for rimboard attachements, but don't see why they couldn't work in concept vertically.

 

[dik]

Is there a need to connect them. Will you soils allow them to be independent. I'd likely frame the trusses to the house with dimensioned lumber connected to the girder truss.

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[dik]

Can you cut away a strip of the ICF and inlet a couple of 2x? and secure to the concrete and then use regular joist hangers?

Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?

-Dik

 

[Bob1680]

I'm looking at concrete post-pouring strip between house's footing and garage' footing. How wide is this strip should be? What's the detail looking like? Thanks.