Using I-joist hangers from shorter header?

[Chris]

I want to know if I can use flush mount joist hangers for a 14" I-joist on a 2x10 header supported by a 2x4 wall in my existing home? The 2x10 boxes in and runs perpendicular to the existing floor joists--which are presumably 2x10s also. There are also the double top sill plates below the 2x10 giving me 12" of solid material below the flooring. I have tried to find this information but most everyone using I-joist are in new construction not remodeling. My goal is to span 22 feet across a garage addition for additional bedrooms above.

[Rich]

With the limited information you've given (i.e. not being able to stand in front of it) I think you'll be fine. As long as the hangers are supported at the bottom by plywood sheathing or something of the sort. This is to get nails in the bottom of the hanger so they are less susceptible to rolling.

[Rich]

I should also add that whoever you purchase the joist package from will design the connections for you and spec a hanger that will work for your situation.

[Chris]

Would the plywood supporting the bottom be below the hanger or a layer sandwiched to the header?

[Rich]

I'm assuming that the wall is sheated with some type of plywood or OSB - that's what I was calling out as supporting the bottom of the hanger where it extends below the 2x10 header.

[Chris]

Ahh... I understand now. My home is sheathed with fireproof gypsm/cement board on the lower half and shiplap boards on the top half. Just couldn't visualize.
Thank you. :)

[mjpliv]

I think if you double check the installation instructions for your hangers/I-joist manufacturer, you will find a requirement to use "all available holes" in the hanger. In some cases the enginnering team for your joist manufacturer can provide you with the minimum required nailing pattern to support the load in question. I would assume that the 2x10 in question has another wall stacked on top of it preventing the use of top-mount hangers which would have been preferable.

Food for thought - assuming bedroom floor live loads at 30 lbs per square foot and dead loads at 15 lbs per square foot (this may vary for your area) and the joists spaced at 16" with a clear span of 22 feet.

The unfactored live load at the hanger will be 440 lbs and the dead load 220 lbs. Factor in 150% for the live load and 125% for the dead load then the total load the hanger must be designed for is a whopping 935 lbs.

Spooky huh!

[Rich]

I've got a few connections on the house I'm working on right now over 6000lbs. They can get some pretty beefy hangers - top flange mount welded to a w16 for a simple span of 16'.

[mjpliv]

Just out of curiosity, do you guys south of the border also calculate your floor loads the same way.

We use -

30 lb live bedroom
40 lb live everywhere else

Maximum live load deflection L/360

Standard dead loads are a total of 15 lbs top and bottom cord combined.

Live loads are factored at 150%
Lead loads are factored at 125%

This is for residential (non-commercial) construction.

[Chris]

Yes, there is a floor above the joist so top mount hangers are out...and seeing as everything to do this option is getting more complicated I'm going to go for the attic trusses instead. Less space but should be able to handle it and actually get it finished.

Which brings me to another framing question. I will now need to make up 5 1/2 or 6 inches depending on the flooring options due to the truss's smaller bottom chord dimensions. That is --with 8 foot walls I will be short of the height needed for matching the existing second floor. Can I keep adding 2x6 sill plated to make up the height or should I have the masonry added to instead?

[Rich]

Talk to your truss manufacturer - they should be able to extend the heel height and create an end bearing truss to accomodate what you want.

[mjpliv]

Don't be too quick to dismiss the clear span floor joists. A simple solution would be to add a second rim of 14" timberstrand flush with the top of the floor and nail the hell out of it into the existing 2x10 rim, plates and studs. That would give you the full support required by the face mount hangers. Ask your engineered floor joist supplier to work it out for you. Also make note of any web stiffeners that may be required in the hanger detail.

As far as increasing the wall heights, additional plates are the easiest. Just make sure the one against the masonary is wolmanized and Has a sill gasket under it.

[Rich]

I know in school Canada had more strict design requirements for structures that we did in the states. Looking at your loading I think that still holds true.
Live and dead loads are pretty much what we use for general purpose and deflection criteria is the same (sometimes up to L/480 depending on client).
But the loading factors are a little different - 125% and 115% respectively (as far as I know anyway).

Just out of curiosity, do you guys south of the border also calculate your floor loads the same way.

We use -

30 lb live bedroom
40 lb live everywhere else

Maximum live load deflection L/360

Standard dead loads are a total of 15 lbs top and bottom cord combined.

Live loads are factored at 150%
Lead loads are factored at 125%

This is for residential (non-commercial) construction.

[Chris]

Do you add the additional sill plates at the bottom or the top of the wall. I assumed they would be added to the top. And is there any nailing specifics necessary or just nail'em together? It will take four additional 2x6 to give me the required 5-6inches. Seems like quite a stack.

[mjpliv]

I'm sorry, now you have lost me. I understood this to be an addition to a house with one edge of the floor hung on the exterior of the existing with the remaining edges supported by some sort of masonary/concrete foundation wall. Apparently there is a wood frame wall supporting these joists.

Instead of adding plates, just order 8' studs instead of precuts. after a mud sill, bottom plate and double top plate you will actually have 8' - 6" (+or-) to play with. There are some hefty loads being applied to these walls so be sure to block the walls at center (minimum) and attach your exterior wall sheathing per your local codes (ie- nail size, spacing, etc.)

I take it you have given up on the clear span joists! If you have, remember that using attic frame trusses will actually increase the load applied to the connection to the existing walls because you have added into the mix some snow/rain loads as well as the additional dead loads associated with it any only reduce a portion of the live loads on the floor portion of the truss.

[Chris]

Sorry to confuse you. I've been going back and forth over doing what you describe with I-joists hanging off one existing wall to the new wall of the addition (i.e. three walls -a typical attached two stall garage addition but limited by space to 22 feet wide instead of 24 and 32 feet deep) The footings and slab are completed with one course more or less above grade. Using I-joists I could build an entire second floor above and use economically priced 32 ft standard trusses perpendiculatr to the 22ft floor joists. It still makes sense to me as far as getting the most bang for your buck and relativley simple to build.

It should have been a simple attached garage. Truss it and be done. But, like most I can use the space. With the attic trusses it still isn't too bad until I started thinking about dormers for light rather than skylights. Paranoid about ice damming here. Had a good 8-10inches last year on the house and am remedying that at the same time as this garage. That is another story all together..2x6 ratfters R-7 insulation 3/12 pitch roof 4 inch overhang. I'm going over that roof with 2x12s pitched at 5/12 with 2foot overhangs and as much insulation as fits with the air space.

I apologize for getting lengthy here. I've already got my precuts delivered and suppose I could exchange. The loading that you talk about from the trusses is definitely why I am going with 2x6 walls but I will also have a single 9foot garage door at both ends of the garage...load bearing walls of the 32ft clear span trusses. I planned on using a parallam beam 5 1/4 x 9 1/2 or two lvl 1 3/4 x11 3/4 for each garage door header, triple blocked cripples. I hope that still sounds safe.